MIG Welding 101: A Beginner’s Guide to Setup, Settings & Technique

You finally dragged the old welder out of the garage, clamped a 3/8-inch plate on the bench, and pulled the trigger — and what came out looked like a lumpy caterpillar with a crater at the end. That first bead is where nearly every welder starts, and the gap between that bead and a clean, stack-of-dimes one is mostly technique, not talent. This guide walks through everything that gap requires: what MIG welding actually is, what gear you need, how to match wire to gas, how to dial in your first settings, and how to fix the five defects that trip up nearly every beginner.

What Is MIG Welding? Understanding GMAW

At its most basic, MIG welding is the trade nickname for gas metal arc welding (GMAW). It’s an arc welding process that uses a continuously fed wire electrode and a flow of shielding gas to join metals together. Rather than having to stop and swap out electrodes like you would with stick welding, the filler metal is fed without interruption. As stated by the American Welding Society (AWS), GMAW is one of the most versatile and efficient arc welding processes, which is a large part of why it’s found in automotive, aerospace, energy, and manufacturing shops all across the world.

The Four Parts That Make It Work

For GMAW to function, four key components have to work in perfect sync with one another:

• The power source: Provides the electricity needed to generate the arc.
• The wire feeder: Pushes the consumable wire through the gun at a precise, controllable speed.
• The MIG torch (gun): Delivers the electrified wire, current, and shielding gas directly to the joint.
• The shielding gas: Flows out of the nozzle to protect the weld from contamination in the surrounding air.

When the trigger is pulled, an electric arc forms between the wire tip and the base metal. That arc melts both the wire tip and a portion of the base metal, forming a molten weld pool. Simultaneously, the shielding gas blankets that pool, and the continuously fed wire melts into it as filler metal. This constant feed is the entire reason MIG is so fast compared to many other processes.

Clearing Up The Naming Confusion

With so many acronyms floating around, it’s easy to get them mixed up. GMAW is the official AWS term for the process. MIG stands for “metal inert gas”, a nickname from its early days of running strictly inert gases. Over in Europe, when using active gases such as CO₂, it’s more commonly referred to as MAG (“metal active gas”). Lastly, flux-cored wire welding (FCAW) is a completely separate process. While it also uses wire feed, it relies on the flux packed inside of a tubular wire for shielding, rather than an external gas supply for most self-shielded wires.

Transfer Modes, Polarity, and Control

Not all MIG arcs behave the same. Depending on your voltage, wire feed speed, and gas, the metal transfers across the arc in one of three ways:

• Short-circuiting transfer: The lowest heat input of the three. The wire actually touches the weld pool, shorts, and pinches off repeatedly. This is the go-to for thin material and out-of-position work.
• Globular transfer: The middle ground. Larger, gravity-driven droplets of molten wire drop across the arc. It’s workable, however, it tends to produce more spatter than the other modes.
• Spray transfer: The hottest and most fluid of the three. Tiny, atomized droplets are propelled across the arc at a rapid rate. This provides the highest deposition and penetration, but is best suited for flat-position welding on thicker material.

This control all comes down to polarity as well. For solid wire GMAW, DC electrode positive (DCEP) is the standard. For most self-shielded flux-cored wires, you’ll want to run DC electrode negative (DCEN) instead. On top of that, proper gun positioning matters, with most welders keeping their MIG gun at roughly a 15-degree angle from vertical to help direct both the arc and the shielding gas down the joint.

Why It’s The Go-To For Beginners

MIG earned its reputation as the default first process for a reason. Its continuous filler feed allows for faster travel speeds and higher deposition rates than SMAW (stick) welding, allowing new welders to cover more ground whilst practicing. It’s also incredibly easy to read the puddle, produces great-looking beads with practice, and has a much lower skill entry barrier than processes that require hand-feeding filler metal. Combine all of that with its versatility, and it’s no surprise that for most hobbyists and shops, the path to learning how to weld starts with GMAW.

Why Beginners Pick MIG — and Where It Falls Short

Every process has a fan club, and MIG has the biggest one in the beginner world. Walk into a fab shop, a farm repair shop, or a home garage and ask the owner which process they would teach a total novice, and most will say MIG without hesitating. But the honest version of that answer carries a few warnings, because the same properties that make MIG fast to learn also make it frustrating in specific conditions. Here is the case for and against, without the sales pitch.

The real advantages

It is the fastest all-round process to pick up. A TIG rod in one hand and a torch in the other is a lot to coordinate. A stick requires you to manage a stiff electrode and build a puddle through the flux coating. MIG gives you one thing to hold, one trigger, and a visible puddle that tells you what is happening. That is why most beginner courses and AWS’s own framing of GMAW puts MIG first, even though TIG is the more “pure” process.

Continuous wire feed removes the electrode-change interruption. With stick welding you stop every few inches to swap a burning electrode, then re-establish your arc and heat. That kills productivity on thin gauge and long joints. A MIG gun feeds filler metal continuously from a spool, so the arc never stops and the heat input stays steady from start to finish.

It lays down less heat per inch than stick on thin material. Stick concentrates a lot of energy into a small, hot arc. On 16 or 18 gauge sheet, that is a fast route to burn-through. Short-circuiting MIG transfer keeps the puddle small and cool enough to handle light material without warping it into a bowl.

The puddle is easy to read. TIG gives you the most control in existence, but it also gives you the most ways to lose control. MIG’s visible, self-adjusting puddle lets a beginner see heat input directly: puddle too big, move faster or turn down the wire feed; puddle too small, slow down.

The material range is wide. Steel, stainless, aluminum, and even some nickel alloys are all within reach once you have the right consumables. That is why MIG is the default in so many shops. If aluminum is on your list, our Aluminum MIG Welding guide covers the prep and gas details that trip up first-time aluminum welders.

It forgives small technique errors. A slightly long stickout, a wandering arc, a little extra travel speed: MIG recovers from these far better than TIG. That forgiveness is what makes it a good teacher.

Where MIG frustrates beginners

You need gas, and gas is a real logistical deal. A cylinder, a regulator, a flowmeter, refills or exchanges, and a supplier within driving distance. It is not a dealbreaker, but it is the most common reason people put the MIG project off for a month.

Wind is the enemy. Shielding gas is doing exactly what it sounds like: it blankets the molten pool and keeps air out. A breeze over 10 or 15 mph will rip that blanket away and expose hot metal to oxygen, producing porosity. Work outside on a calm day, or build a wind screen. No machine setting fixes blown shielding gas.

100% CO2 is cheap but messy. As ESAB explains, pure CO2 is cost-effective and penetrates well, but it produces more spatter, more fume, and a less stable arc than argon-based blends. Pure CO2 is fine for thicker mild steel. On anything thin or cosmetic, a 75/25 argon-CO2 blend behaves much better.

It is not the right tool for every job. Very thin material and tight, heat-sensitive work both want a process you can control precisely, and MIG’s continuous heat input is a blunt instrument by comparison.

The real beginner limitation is heat control, not arc control. Anyone can hold an arc. Holding a puddle at the right size while moving at the right speed, on material that changes thickness mid-joint, is the actual skill. Nearly every defect you will chase in your first month traces back to too much or too little heat in one place.

MIG vs TIG vs Stick vs Flux-Cored

Process	Learning curve	Filler changeover	Typical applications	Spatter	Shielding gas	Best use
MIG (GMAW)	Lowest	Automatic, continuous feed	Auto repair, sheet metal, fabrication, general steel	Low to moderate	Yes (argon blend or CO2)	Best all-round beginner process
TIG (GTAW)	Steep	Manual, rod added by hand	Aerospace, thin stainless, artistic work, precision	Almost none	Yes (argon)	Cleanest bead and maximum control
Stick (SMAW)	Moderate	Manual electrode swap	Field repair, outdoor work, heavy plate, shipbuilding	Moderate	No	Dirty, windy, remote, one-off jobs
Flux-Cored (FCAW)	Low	Automatic, continuous feed	Structural steel, shipbuilding, outdoor fabrication	High when self-shielded	No (self-shielded) or optional	High deposition with no gas to carry

TIG deserves a specific note: it has no built-in filler feed, so the welder adds filler by hand. That slows production and demands real coordination, but it is also exactly why TIG produces the cleanest, most precise bead available. TIG is a natural second process, not a first one. Aerospace TIG welding illustrates the standard TIG is held to once you get past the learning curve.

Stick deserves an equally fair hearing. Because SMAW does not depend on a shielding gas envelope, it works in wind, dirt, rain, and on greasy surfaces that would poison a MIG weld. Many experienced fabricators consider it the process that still wins in the field, and for good reason.

The Equipment: What You Actually Need to Buy

Most beginners make the same mistake here: they buy the biggest, most expensive machine they can find, then realize they can’t weld anything because they’re missing a spool of wire, a cylinder of gas, and a ground clamp. A MIG welder is only one piece of a working setup. Get the pieces in the right order and you’ll be welding this weekend.

The Five Essential Components

Every MIG setup, from a $500 home-shop unit to a $3,000 production machine, contains the same five working parts:

1. Power source — the welder box that turns wall power into controlled DC current.
2. Wire feeder — the motor and drive rolls that push filler wire from the spool into the torch at a set speed.
3. Welding gun (torch) — the handle and barrel that carry the wire, the current, and the shielding gas to the arc.
4. Shielding gas supply — the cylinder, regulator, and flowmeter that blanket the arc in argon, CO2, or a blend.
5. Work clamp — the ground lead that completes the electrical circuit through the workpiece.

Buy all five and you have a welder. Buy four and you have a very expensive paperweight.

Start With the Machine

For a home shop, aim for a multi-process inverter in roughly the 140-amp class that runs MIG, stick, and TIG. Two reasons. First, a 140-amp machine covers essentially everything a beginner will ever weld: 16-gauge up through 3/8-inch steel with room to spare. Second, the stick and TIG modes mean you are not locked into one process forever, and a stick mode is a lifesaver for rusted or awkward joints where a MIG gun will not fit.

Inverter machines became the default for good reason. Compared with the old transformer-style welders, they run cooler, weigh dramatically less, arc strike faster and more reliably, and give you far smoother control over heat input. They also dropped in price to the point where a good 140-amp inverter is one of the best values in the entire shop.

Two more machine features worth paying for:

• A built-in wire feeder. Every beginner machine should have one. A separate feeder is a production-shop accessory, not a home-shop necessity.
• Spool size. A home machine handles10- or 12-pound spools. A 33-pound spool (or a 44-pound “pound spool”) only makes sense if you buy a separate feeder and have somewhere to hang it. Buy 10-pound spools while you learn.

Check for a material program that lets you dial in steel, stainless, or aluminum, and confirm the polarity switch. Most modern machines handle that for you, but older and budget units may require you to swap leads manually.

The Torch and Its Wear Parts

Four consumables live inside the MIG torch, and all four are sized to your wire diameter. This is where beginners lose an afternoon:

• Liner — the coiled tube that guides the wire from the feeder to the gun. It must be the right length for your torch and the right material for your wire. Aluminum and flux-cored wire need special liners.
• Contact tip — the copper or copper-plated tip the wire feeds through. A .035 contact tip will not feed .045 wire correctly. It will jam, arc badly, and throw spatter.
• Nozzle — the ceramic or metal cup that shapes the gas flow around the arc. It does not touch the wire but it does touch the puddle, so it burns out and needs replacing regularly.
• Gas diffuser — the small black plastic or brass part inside the nozzle that spreads the shielding gas evenly.

You also want a spare torch or at least a second gun cable. Torch cables stiffen, crack, and eventually fail at the trigger, and swapping to a known-good torch instantly rules out one whole category of problems.

Gas Cylinder, Regulator, and Flowmeter

A single-cylinder setup needs a cylinder of shielding gas, a regulator, and a flowmeter. Argon and CO2 cylinders are usually rented or exchanged through a local welding supply house, so you are buying the gas by the pound or the fill rather than owning the tank. Some supply companies also rent regulators and flowmeters, which is a smart move if you are unsure about fitting one to a cylinder.

Two cylinder details beginners miss: the cylinder must be chained upright whenever it is in use, and you want a flowmeter with a ball so you can read and adjust the gas volume in actual cubic feet per minute. A plain gauge tells you pressure, not flow.

Need to know what to ask for at the counter? Our Air Gas welding supply guide walks through cylinder sizes, regulators, and the differences between argon, CO2, and blends.

The Work Clamp Is Not Optional

The ground clamp, or work clamp, is the single most skipped item in beginner gear lists and the cause of half of all “the arc is acting weird” complaints. It must attach directly to the workpiece you are welding so the circuit returns through the metal you are actually joining.

Clamp onto a random piece of shop steel and your current takes the easy path through that steel instead of through the joint. You get heat where you don’t want it, a cold joint where you do, and erratic arc behavior that sends beginners hunting for a machine problem that does not exist. Clamp as close to the joint as practical, on the same piece, and if the work is dirty, grind a bare spot to clamp on.

PPE: Buy These Before the Welder

OSHA requires helmets or hand shields for all arc welding operations, and eye protection for helpers and attendants as well. See the OSHA welding, cutting and brazing guidance for the full requirements.

• Auto-darkening helmet — filter lens that darkens when you strike the arc. Look for adjustable shade and a comfortable headband. This is the one place not to cheap out.
• Safety glasses — wear theseunder the helmet, and wear them when grinding or chipping slag.
• Flame-resistant clothing — FR shirt and pants, leather apron for overhead or spattery work.
• Leather welding gloves — supple leather for TIG and handling, heavier gauntlet for MIG.
• Safety footwear — steel or composite toe, heat-resistant, no exposed laces near spatter.

Shop Gear You Will Use on Day One

• Sturdy welding table or fixture — thick steel plate on legs, or a heavy workbench that will not shuffle when you push the torch.
• Angle grinder — with cutting discs for trimming stock and flap discs for cleaning and blending.
• Chipping hammer and wire brush — for slag removal and cleaning before the next bead.
• Soapstone and a permanent marker — marking your work; soapstone survives the heat, markers do not.
• Straightedge — checking bead profile and flatness as you learn.

Realistic Budget Tiers

Tier	Machine	Typical total with gas and consumables
Entry / garage	140-amp inverter, MIG/stick	roughly $600 to $1,100
Mid-range / serious hobbyist	140 to 180-amp inverter, MIG/stick/TIG	roughly $1,200 to $2,200
Shop-grade	250-amp and up, multi-process, spool gun capable	$2,500 and above

Those totals include a cylinder of gas, a regulator and flowmeter, a spool of wire, a helmet, and a starter pile of consumables. Gas and wire are consumable costs you keep paying, so factor them into a monthly budget rather than a one-time purchase.

Setting Up Once You Have the Gear

Once the equipment is in hand, our welding equipment guide covers fitting a regulator and setting flow. To get sensible starting numbers for your machine, Miller’s MIG solid-cored welding setting calculator lets you pick the material (steel, stainless, aluminum) and wire size and generates starting settings you can adjust from.

If your first project involves aluminum, prep matters more than any setting. Our guide to cleaning aluminum properly before welding covers the oxide removal that causes most of the porosity and feed problems beginners blame on the machine.

One last piece of equipment advice that costs nothing: keep a notebook at the bench. Machine model, wire, gas, tip size, and the settings you used on every bead. That log will teach you more in a month than a dozen hours of random trial and error, and it is the single cheapest tool in the shop.

Consumables and Gas: Matching Wire, Gas, and Metal

Most beginner frustration with MIG welding comes down to two cheap consumables: the wire and the gas. Get those matched to your base metal and the machine starts behaving like a different welder. Get them wrong and you will spend a week chasing porosity, spatter, and cracking that no amount of knob-turning will fix.

So let’s decode the labels. When you look at a spool of MIG wire, the classification code printed on it is not marketing fluff. It is an AWS (American Welding Society) standard classification, and it tells you three things at a glance: what the wire is made of, how strong it is, and whether it needs shielding gas. The AWS describes GMAW as one of the most versatile arc welding processes, and the wire classification is a big part of why that versatility exists.

Reading an AWS Wire Classification Code

Take a typical spool label: ER70S-6. Every character means something.

• E stands for electrode, the AWS term for the filler metal consumed by the arc.
• R indicates the wire is a rod, which is what MIG and TIG filler wire is. Stick electrodes are classified differently, and the all-position rod guide covers that side.
• 70 is the tensile strength in thousands of pounds per square inch. ER70S-6 is rated at 70 ksi, which is plenty for most mild steel work.
• S means solid wire. A T means tubular, meaning a flux-cored wire that carries its own flux inside. GS means gas-shielded, and when it appears after the T, as in E71T-GS, it means self-shielded: the wire is designed to work with no external shielding gas at all.
• The last digit, 6 in this case, is a usability code that describes alloy content and handling characteristics, such as how the wire behaves in the puddle and whether it can be used in all positions.

You do not need to memorize every code. You need to recognize the four you will actually buy.

The Four Wires You Will Actually Use

ER70S-6 (solid, mild steel). This is the default beginner wire and the default in most home shops. It is a copper-coated solid wire containing a small amount of silicon, which helps the bead flow and produces a clean, easy-to-weld bead on carbon and mild steel. It is available in spool sizes from 1 pound up to 44 pounds, and the common diameters are .030, .035, .045, and .060 inch. If someone hands you a spool of solid wire and it is not labeled otherwise, it is almost certainly this.

E71T-GS (self-shielded flux core). This is the wire that saves a Saturday when you are welding a trailer hitch outside in the wind. The flux inside the wire creates its own shielding, so you need no cylinder, no regulator, and no flowmeter. It is slightly less pleasant to weld than solid wire, with more spatter and a rougher bead, but it will happily weld dirty, rusted, or painted steel that you would not want to clean for a gas-shielded process. Note the polarity requirement: self-shielded flux-cored wire generally wants DC electrode negative (DCEN), which is the reverse of solid MIG wire.

ER308L (stainless steel). The “L” means low carbon, which is what you want for 304 and 316 stainless because it minimizes sensitization and carbide precipitation. Stainless MIG typically runs on a tri-mix of argon, helium, and carbon dioxide, and critical or cosmetic work benefits from back-purging with shielding gas behind the bead to keep the backside from oxidizing and discoloring.

ER4043 and ER5356 (aluminum). This is the one place beginners routinely pick wrong. ER4043 is easier to weld and is the better choice for fillet welds, most general fabrication, and repair work. ER5356 offers higher strength and a better match to the anodized color of the workpiece, which is why it is the standard on trailer and boat work. Our complete guide to aluminum MIG welding covers the process in detail, and the guide to prepping aluminum properly handles the cleaning step that makes or breaks the job.

The Gas Side

Gas is what keeps the molten pool clean of air. The air contains oxygen and nitrogen, and when they get into a weld you get porosity, brittle oxides, and a bead that looks like it has holes in it. The shielding gas is not there to make the arc pretty. It is there to keep the air out.

• 75/25 argon-CO2 (often labeled C25) is the standard for mild steel. The argon stabilizes the arc and gives you a clean, low-spatter bead that is easy to control. This is what you want for almost all beginner steel work, and the AWS guidance for steel is an argon-CO2 blend.
• 100% CO2 is cheaper per cubic foot and widely available, and it will work fine on mild steel. The tradeoff is noticeably more spatter, a harsher arc, and a slightly less controllable puddle, which is why most shops that own both mix their own 75/25.
• 100% argon is the choice for aluminum. Pure argon gives a clean, stable arc on aluminum and helps with the heat control that aluminum demands.
• Tri-mix (typically argon, helium, and CO2) is the standard blend for stainless steel. The helium helps with penetration and travel speed, and the CO2 stabilizes the arc. The AWS aluminum welding guidance from Welding Digest is a useful companion read.

Matching Table: Base Metal to Wire and Gas

Base metal	Wire	Gas	Notes
Mild / carbon steel	ER70S-6	75/25 argon-CO2	Beginner default. Clean bead, low spatter, easy puddle control.
Dirty or outdoor steel	E71T-GS flux core	None	Self-shielded, DCEN polarity. More spatter, no cylinder needed.
Stainless 304 / 316	ER308L	Tri-mix (Ar/He/CO2)	Expect hexavalent chromium in the fume. Back-purge critical work.
Aluminum (fillet, general)	ER4043	100% argon	Easier to weld, better flow. Clean the metal immediately before welding.
Aluminum (high strength, anodized)	ER5356	100% argon	Stronger than ER4043, matches anodized color better. See the aluminum flux core welding guide for the no-gas alternative.
Galvanized / zinc coated	ER70S-6	75/25	Weld outdoors or with strong extraction. Zinc fume causes metal fume fever.

Wire Diameter: Small vs. Big

Wire diameter is the other half of the decision, and it is mostly a question of how much heat you can feed into the joint without warping or burning through it.

• .030 inch is your thin material wire. It works on anything from 26-gauge sheet up to about 1/8 inch, and it is the easiest to control on thin steel because you can feed it at a low, steady rate.
• .035 inch is the sweet spot for most home shop work. It handles 1/8 inch through 1/4 inch mild steel and gives you a slightly hotter, more forgiving arc than .030. Most 140-amp machines run .030 and .035 without complaint.
• .045 inch is for 1/4 inch plate and up, and it deposits faster. Many machines will run it, but check that your machine, gun, liner, and contact tip are all rated for it.
• .060 inch is heavy plate and high deposition work. It needs a machine with the amperage and drive system to push it, which usually means stepping up a class or two.

As a rule of thumb, stay at or below .035 until you are comfortable reading your own puddle. Jumping to .045 too early is a common beginner move that adds spatter and heat for no benefit.

Polarity: The Tie-Breaker

When the machine asks you for polarity, it is really asking which way to run the current. Solid MIG wire runs DC electrode positive (DCEP), where the work is negative and the torch is positive. Most self-shielded flux-cored wire runs DC electrode negative (DCEN). Get this backwards and the wire will not feed, the arc will be erratic, and the liner will burn up quickly. If a spool is not clearly labeled, the AWS wire classification and the manufacturer’s chart on the machine will tell you which way to set the lead switch. Wire feed speed calculators such as the Miller MIG solid core welding calculator are also a good starting point for matching wire size to amperage.

Buy your wire and gas before you buy the machine, and buy the size that matches what you actually plan to weld. Most beginners end up with a 1/4 inch steel bracket or a backyard gate in mind, and that tells you everything: ER70S-6, .035 wire, 75/25 blend, DCEP. Everything else on the spool rack can wait.

Your First Weld: Settings, Technique, and Reading the Arc

Here is the part most instructionals skip, and it is the part that decides whether you will like welding. A MIG machine hands you three numbers: voltage, wire feed speed, and travel speed. Once you understand how those three interact, the machine stops being a mystery box and starts being a tool you can steer. ESAB explains it plainly: on a constant-voltage wire-feed machine, voltage controls the length of the arc while wire feed speed sets the amperage, and the balance between the two is what governs penetration.

Control	What it really does	Beginner mistake
Voltage	Sets arc length and bead width	Leaving it at the factory default and only touching wire feed speed
Wire feed speed	Effectively sets amperage and how much filler metal arrives per second	Feeding faster without adding voltage, which spits the wire sideways
Travel speed	Sets how much heat lands per inch of joint	Crawling along, dumping a huge puddle into the joint

Voltage: How Long the Arc Is

Raise the voltage and the arc stretches longer, which flattens and widens the bead. Lower it and the arc shortens, giving a narrower, more focused bead with more penetration. Voltage is not a heat dial in a MIG machine, even though it feels like one. It is an arc length dial. That is why voltage and wire feed speed must be adjusted together, because wire feed speed is what actually feeds current into the puddle.

Wire Feed Speed: The Amps You Actually Get

Push wire feed speed up and the machine feeds wire faster, which requires more current, which means more heat and a bigger puddle. It also shifts the transfer mode. Push it down and you get a cooler, tighter, easier-to-control arc. Most beginners fight the arc by cranking wire feed speed, then blaming the voltage. The relationship is fixed: more wire feed speed needs more voltage to match.

Travel Speed: Heat Per Inch

Your travel speed is the one control that lives in your hands. Move faster and less heat lands on any given inch, so the bead is narrower, flatter, and easier to burn through on thin plate. Move slower and you get a wider, more convex bead with deeper penetration. On 16-gauge steel you might travel at 12 to 15 inches per minute. On 1/4-inch plate, 4 to 6 inches per minute is more typical. Measure your speed once with a tape and a stopwatch so you know what “right” feels like later.

The Balance Between Voltage and Wire Feed Speed

Get the balance wrong in one direction and you get a harsh, wide, flat, spitting mess. Set wire feed speed high but leave voltage low, and the wire smashes into the puddle, shorts constantly, and throws spatter in every direction. The bead comes out wide, flat, and ugly.

Get it wrong the other way and you get a long, cold, lazy arc that wanders around the joint and refuses to fuse. Weld it and you can often tap the bead off with a fingernail. That is a textbook lack of fusion, and it is almost always a symptom of a voltage setting that is too high for the wire feed speed.

Your aim is a stable transfer mode for the material in front of you. AWS describes short-circuiting transfer as a technique in which the electrode contacts the base metal and briefly shorts, which gives better control on thin materials. On thicker plate, you want spray transfer, where the wire hits the puddle as small droplets and the arc sounds like a smooth hiss. Same machine, same two knobs, completely different feel.

Listen to Your Welder

Your ears are the fastest diagnostic tool in the shop. Learn three sounds and you will catch a bad setup before you finish the first foot of bead.

• Steady crackle and pop: Normal short-circuiting transfer. This is the sound you want on thin sheet and light structural steel.
• Smooth hiss: Spray transfer. Clean, concentrated, and the sound of a good bead on thicker material.
• Sputtering buzz: Something is off. Often a stickout that is too long, a gas mix that does not suit the wire, or an unstable cylinder. A sputtering buzz usually comes with visible popping and weak penetration.

Hold the Torch Like a Hot Glue Gun

Not like a pencil. A pencil grip puts your wrist in the way and gives you no control over the nozzle. Use a leading-hand grip, with your dominant hand forward on the torch neck and your other hand steadying the body and guiding the wire direction. You are holding a hot glue gun that you are also trying to steer precisely, so your hand needs to be in charge of the aim.

Keep the gun angle at roughly 15 degrees from vertical, tilted into the direction of travel, and the nozzle just off the work so you can see the joint and the leading edge of the puddle. If you cannot see your puddle, you cannot control it. Dragging the nozzle lightly along the plate gives you a consistent distance and a free cooling path for the gas.

Control the Puddle, Not the Whole Bead

Watch the leading edge of the puddle, the point where the arc pushes the liquid metal forward. That is the part that tells you the heat. If the leading edge is lagging, narrow, or sitting still, you are moving too fast and the puddle is about to break through. If it is bulging and pushing ahead of you like a rolling wave, slow down or ease off the wire feed speed.

On thin material, use a small circular or up-and-down motion to keep the puddle small and let it solidify behind you. On thicker plate, run a straight stringer bead and let the puddle push along in a narrow lens shape. Wide weaving beads look impressive and waste heat, and they are a common beginner crutch that hides bad puddle control.

Starting and Stopping the Bead

Start in the corner of the joint, not in the middle. Hold the nozzle about 1 inch back from the start point, strike the arc, then let the puddle form and move forward before you begin your travel. Backing up slightly as you start is a good habit, because it gives you a moment to confirm the arc is sound before committing to the joint.

At the end of the bead you have two options. Fill the crater by holding the trigger on briefly and letting the wire pile up, or run off the edge of the work and let the arc break naturally. Running off the edge is easier to master and rarely leaves a nasty dimple. Whichever you choose, do it deliberately. A crater you ignore is a crack waiting to happen.

Common Beginner Defects and How to Fix Them

Nobody starts out welding clean beads. A short list of defects covers nearly every ugly first weld, and each one traces back to a setting you can change.

Porosity: The Holes That Look Like Someone Poked the Weld

Porosity is small round holes or pits in the bead, often clustered near the start or the end. It is the most common MIG defect, and the cause is almost always one of four: contaminated metal, not enough shielding gas, a leak in the gas system, or wind pulling the shielding envelope off the puddle.

Mill scale, rust, paint, cutting oil, grease, and the oils your hands leave on steel boil off in the arc and get trapped in the weld. Clean the joint with a stainless brush wheel, wipe it with solvent or degreaser, and weld within a few minutes.

Check the gas next: roughly 15 to 20 CFM for most 75/25 work, plus a soapy water leak test on the hose, regulator, and torch connection. Wind steals shielding too, so screen the arc outdoors. Aluminum forgives even less, because aluminum oxide forms almost instantly, as our aluminum MIG welding guide shows.

Excessive Spatter: The Ballooning, Popping Mess

Spatter is the orange ball of metal that pops off the weld and litters your plate. A little is normal, especially on 100% CO2. A lot means something is off, and three causes cover nearly every case.

Voltage too low for the wire feed speed is cause number one. Wire feed speed sets the current you are asking for; voltage sets the arc length that carries it. Too little voltage gives a short, wide, harsh arc and balls the wire up at the tip instead of melting it cleanly. Raise voltage a little at a time until the popping eases.

Gas matters too. 100% CO2 is cheaper and works fine on thicker mild steel, but it makes noticeably more spatter than a 75/25 argon blend, and on thin material it is a losing proposition. If you run C25 and the spatter is annoying, the cheapest fix is a better mix, not a better machine. Check stickout as well: wire sticking out more than about an inch leaves a long, wandering arc that adds spatter, so bring the contact tip closer to the work.

Undercut: The Groove Along the Edge

Undercut is a groove dug into the base metal at the toe of the weld, where the bead meets the plate. It is a heat and travel speed problem: too much heat and too fast a travel drags the arc across the joint edge and melts base metal away faster than the filler can replace it.

Slow down, keep the puddle small, and move the wire toward the center of the joint. Use a tighter weave or a plain stringer bead, and hold the arc slightly longer where you are dwelling. On a fillet, hold the arc at the corner, not out over one leg where it can chew the edge.

Burn-Through: The Hole Where Your Bead Should Be

Burn-through happens when you apply more heat than the material can absorb before it melts through, and it hits thin gauge and fast welds with a large puddle most often. Reduce the wire feed speed, trim the voltage slightly, and slow your travel so the puddle fills in behind itself. A backing strip of heavier scrap steel under the joint catches the droplet and saves the part, while a copper or steel backing bar works as a heat sink, pulling heat out of the joint.

Lack of Fusion: The Weld That Looks Fine and Is Not

Lack of fusion is a cold weld. The bead sits on the surface or at the edge of the joint without bonding to the base metal, and it flakes right off if you bend or chisel it. Causes are too little heat at the joint, travel speed that is too fast, incorrect polarity, or contaminated surfaces.

The fix is more heat in the right place: slow down, add wire feed speed, clean the joint, and confirm polarity. Solid wire MIG runs DCEP, so a machine switched to DCEN by accident makes the wire behave badly and the bead will not fuse. On clean bare mill steel with sane settings, drop travel speed by a quarter and see what happens.

Convex, Lumpy Beads and Stubbing

A fat caterpillar bead is usually too much wire going in too slowly, or an arc too wide for the filler being delivered. Slow your travel, add a little voltage to narrow the arc, or turn the wire feed speed down. A row of tiny sausages with the wire poking through is stubbing: the voltage is too high for the wire feed speed, so the wire melts back faster than it feeds.

Other feeding problems: the wire will not feed at all (check drive roll tension, liner burrs, contact tip size, and any kink in the liner), the wire feeds but does not reach the work (the liner is too long or the gun is not seated), or the wire feeds backward and bird-nests behind the drive plate (reversed polarity or gun).

Symptom	Likely cause	Fix
Holes or pits in bead	Dirty or oily work, low flow, leak, wind	Stainless brush and solvent, check flow and leaks, shield from wind
Heavy spatter	Voltage too low for WFS, CO2 on thin work, long stickout	Raise voltage, use 75/25 blend, shorten stickout
Groove at weld toe	Excess heat and travel speed	Slow down, keep puddle tight, hold arc at joint center
Melted hole	Too much heat on thin material	Reduce WFS and voltage, add a backing strip
Cold, non-bonding weld	Little heat, fast travel, wrong polarity, dirty surfaces	Add heat, slow travel, verify DCEP, clean the joint
Fat, lumpy bead	Too much wire, slow travel, wide arc	Reduce WFS or speed up travel, raise voltage
Wire spits or stubs	Voltage too high for WFS, bird-nesting, reversed gun	Lower voltage, clear the drive plate, confirm gun polarity

When a defect shows up, cut the test coupon open and look at it. A bead that looks fine from the top can be full of porosity underneath, and cutting and bending coupons builds the judgment that eye alone cannot give you. AWS notes that the variable most people overlook is not the machine but the joint preparation and the cleanliness of the surface going into the arc.

These defects are not signs of a bad machine or a missing talent, only one variable in a learnable three-variable system. AWS publishes guides and handbooks covering filler metal and process fundamentals, and the AWS Certified Welder education resources are a good next stop. Work the table, keep the log, and the ugly first bead turns into a good tenth bead faster than you expect.

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Safety: Fumes, Fire, Electricity, and PPE

Welding ranks among the more dangerous jobs in the trades, and the reason is not mysterious. You are melting metal in an open cloud of toxic fumes, sitting next to a live electrical supply, in a room full of sparks and hot spatter. Nearly every serious welding injury or illness traces back to a rule written down decades ago and then ignored for five minutes. Learn those rules before your first arc and you sidestep most of the bad outcomes.

Welding fumes and hexavalent chromium

Welding fume is not smoke from burning material. It is a fine particulate aerosol of metal oxides created when the arc vaporizes the base metal, the filler metal, and whatever is on the surface: mill scale, paint, galvanizing, rust, cutting oil, and solvent residue. Some of it is merely unpleasant. Some of it is dangerous.

The headline concern is hexavalent chromium, a known carcinogen generated when welding stainless steel or chrome-plated and chrome-coated materials. OSHA sets a permissible exposure limit of 5 micrograms per cubic meter of air as an 8-hour time-weighted average, and its dedicated exposure controls guidance spells out how to stay under it.

The order of protection is not up to you. OSHA requires feasible engineering controls (extraction, ventilation, enclosure) and work practice controls first. Only when those cannot bring exposure under the limit do you add respiratory protection. In general industry, a formally regulated area must be established around hexavalent chromium work, with access limited to trained and properly fitted personnel.

Ventilation requirements you need to know

Ventilation is the biggest lever you have for controlling fumes, and the federal minimums are written down in OSHA 1910.252. Mechanical ventilation is required in spaces under 10,000 cubic feet per welder, in rooms with ceilings under 16 feet, and in confined spaces, at a minimum of 2,000 cubic feet per minute per welder. A small garage with a single MIG welder needs real extraction, not an open door in January.

Local exhaust hoods are the better answer because they capture fume at the source. OSHA calls for a minimum of 100 linear feet per minute of capture velocity at the arc, and the standard’s airflow table shows how fast that number climbs as a hood moves away from the work:

Distance from arc	Minimum airflow
4 to 6 inches	150 CFM
6 to 8 inches	275 CFM
8 to 10 inches	425 CFM
10 to 12 inches	600 CFM

Put another way: a hood sitting a foot from the arc needs roughly four times the airflow of one parked four inches off the puddle. Position matters more than horsepower.

Fire prevention

Welding spatter travels further and burns hotter than most people expect. It will melt roofing felt, scorch wood studs, and ignite rags that look perfectly dry. OSHA requires combustibles be relocated at least 35 feet (10.7 m) from the worksite where practicable, and where that is not possible you protect what remains with fire-resistant welding curtains or blankets.

When combustibles cannot be moved 35 feet, or when work happens on the far side of a wall or fixed barrier where sparks cannot be seen, a fire watch is required. The watch is not a way to look busy: it stays in position during the work and for at least half an hour after welding stops, so smoldering material has time to show itself. Keep an appropriate fire extinguisher within reach at all times.

OSHA 1910.252 incorporates NFPA Standard 51B for fire prevention in cutting and welding by reference, so standard trade practice and the legal requirement point in the same direction.

Personal protective equipment

PPE is the last line of defense, and helmet choice is where beginners get it wrong most often. OSHA’s shade-number guide is specific: shade 12 for gas-shielded arc welding of ferrous materials, shade 11 for nonferrous metals. Going too light risks a permanent arc-flash burn to your face. Going too dark is merely uncomfortable, and honestly worth it on your first few beads.

Item	What to look for
Auto-darkening helmet	Shade 12 for steel, shade 11 for aluminum and other nonferrous work; a headband that fits snugly
Safety glasses	Worn under the helmet, for grinding and chipping debris
FR clothing	Flame-resistant jacket and trousers or shirt; sleeves down, no cuffs hanging
Gloves	Heat-rated welding leather gauntlets, sized so you can still handle the gun
Leather apron	For heavy spatter work, especially vertical and overhead
Footwear	Safety-toe leather boots, not sneakers

Shop suppliers such as Airgas Welding Supplies stock the full range of helmets, respirators and FR clothing if you want one place to compare brands before you buy.

Cylinders, confined spaces, and electricity

Gas cylinders are heavy, pressurized, and a top-three cause of shop injuries when mishandled. Store them upright, chained or otherwise secured, with the valve closed when not in use, and never move a cylinder by the cap. Most local suppliers will deliver, exchange, and set up cylinders for you, and their safety guides, like the one at AllGas Welding Supply, are worth reading before your first fill.

Confined spaces get their own hard rules. Gas cylinders and welding machines must be left outside the space, and an attendant with a preplanned rescue procedure must be stationed outside, observing the welder at all times. No trained attendant and rescue plan means you do not do the job.

Electrically, the grounding setup is what protects you. Always attach the work clamp directly to the workpiece, as close to the weld area as practical, so current has a short path back to the machine instead of seeking a path through you. OSHA requires ground return cables be properly insulated and connected, and industry practice, reinforced by NFPA 70E, keeps electrode and work leads to 35 feet or less to limit voltage drop and shock hazard.

Finally, check the label. OSHA requires filler metals and fusible granular materials to carry the notice: “Do not use in areas without adequate ventilation. See ANSI Z49.1 Safety in Welding, Cutting, and Allied Processes.” It is a small line of text, but it is the manufacturer’s way of telling you exactly what the fume will do if you weld it in a closet.

Welding Different Metals and Thicknesses

Most beginner guides stop at “here is how to set your machine” and leave you to figure out the rest on your own. That is where a lot of people plateau. The settings that produce a clean bead on 16-gauge mild steel will spit spatter and burn holes in 18-gauge, and the wire that works beautifully on aluminum will crater on stainless. Material and thickness change the rules, so here is how they actually shift.

Mild Steel: The Baseline Material

Mild steel is where you should spend your first weeks. Get comfortable from 18-gauge up to 1/4 inch, because that range covers most of what a hobbyist or a small shop will ever weld. AWS recommends an argon-CO2 mixture for mild steel, and that 75/25 blend is the reason MIG is so forgiving on this metal. The argon stabilises the arc and the CO2 helps with penetration and a flatter bead.

Thin material calls for short-circuiting transfer. The wire repeatedly touches the puddle, the arc extinguishes, the wire melts, and it restarts. That staccato sound is the audio cue that you are in the right mode. Short circuiting means lower heat, which is exactly what you want at 20 or 22 gauge. Note the voltage-to-wire ratio: as wire diameter goes down, voltage comes up slightly relative to wire feed speed, because you need a slightly longer arc to keep the transfer clean and stable.

On thin gauge, keep the puddle small and travel fast. A big puddle on 18-gauge is a burn-through waiting to happen. On 1/4 inch and heavier, you move into spray transfer, keep a longer, narrower bead, and slow down.

Thick Steel: Multi-Pass Reality

Anything at or above 1/4 inch should be approached as a multi-pass job. Do not try to fill a 1/2-inch gap with one fat bead. Clean the root between passes, keep the stringer beads narrow, and build up in layers.

Stringers beat wide weaves for a beginner. A weave spreads the same heat over a wider area, which increases distortion and makes it harder to hold a consistent puddle. A stringer gives you one clean, repeatable bead that you can stack.

Stainless Steel: Heat Is the Enemy

Stainless welds with ER308L for 304 and 316 base metal, and AWS recommends a tri-mix shielding gas for stainless work. Stainless conducts heat noticeably worse than aluminum, so the heat concentrates at the joint instead of rushing away. That means the puddle stays hot, the bead spreads, and the workpiece distorts. Distortion is the bigger problem on stainless, not penetration.

Control heat input, use tack welds with restraint, and think hard about joint fit-up and sequence. For critical or cosmetic work, back-purge the root side with argon so the underside does not oxidize and lose its corrosion resistance.

Do not forget the follow-up step: stainless welds must be cleaned and passivated after welding to restore the chromium oxide layer that gives stainless its corrosion resistance. Skip it and the joint rusts.

And expect hexavalent chromium in the fume. Welding stainless generates fumes containing hexavalent chromium, which is why OSHA’s exposure controls on hexavalent chromium matter here. If you are new to stainless, start with our aluminum MIG guide companion material on alloy handling, and treat fume extraction as non-negotiable rather than optional.

Aluminum: A Different Animal

Aluminum conducts heat several times faster than steel. The puddle cools and solidifies quickly and heat sinks away from the joint, which is why aluminum MIG often needs higher amperage and slower travel speed than the same thickness of steel. AWS describes low-voltage short-circuiting as the technique for thin material, and identifies the spool gun as the standard way to handle aluminum MIG, since a standard feeder and liner struggle to push aluminum wire smoothly.

Cleanliness is everything. Aluminum oxide forms instantly and melts at a much higher temperature than the base metal, so it will spit out of the weld like a marble. Scrub the joint with a dedicated stainless brush and acetone immediately before welding, keep the filler wire clean too, and do not touch the prepared surface with your gloves.

For filler, ER4043 is a good general choice for fillets, and ER5356 gives you higher strength and better crack resistance where the joint demands it. Our aluminum cleaner guide covers preparation in more detail, and how aluminum flux welding works is worth a look if you are weighing whether the job really needs MIG at all.

Galvanized and Zinc-Coated Steel

Welding galvanized steel releases zinc oxide fume, which causes metal fume fever, an unpleasant flu-like condition that can hit hours after exposure. Weld outdoors or with strong extraction. OSHA 1910.252(c)(6) requires indoor welding on zinc-bearing base metals or zinc-coated materials to be done with local exhaust ventilation, and you should treat the fume as a serious health issue rather than a nuisance. Grounding the work or using a generous protective gas pre-flow helps, but neither replaces extraction.

Starter Settings: Where to Begin

Treat the numbers below as conversation starters, not gospel. Use them as your first attempt, then adjust with the MIG solid core welding calculator and your machine’s own chart.

Material	Thickness	Wire / Gas	Transfer	Starting Point
Mild steel	18-20 ga	.030 ER70S-6, 75/25	Short circuiting	~3.5-4.0 V, WFS ~250-300 ipm, short travel
Mild steel	1/8 in	.030 ER70S-6, 75/25	Short circuiting	~4.0-4.5 V, WFS ~300-350 ipm
Mild steel	1/4 in	.035 ER70S-6, 75/25	Spray	~4.5-5.0 V, WFS ~350-400 ipm, multi-pass
Mild steel	3/8 in+	.045 ER70S-6, 75/25	Spray	~5.0-5.5 V, WFS ~400-450 ipm, multi-pass
Stainless	18 ga-1/8 in	.030 ER308L, tri-mix	Short circuiting	~8.5-9.0 V, WFS ~220-280 ipm, minimal dwell
Aluminum	1/16-1/8 in	.030-.035 ER4043/ER5356, 100% argon	Short circuiting	~18-19 V, WFS ~280-330 ipm, spatter-prone, clean first
Galvanized steel	16 ga-1/8 in	.030 ER70S-6, 75/25	Short circuiting	~4.0-4.5 V, extract fumes aggressively

One last practical note: a spool gun is the single upgrade that changes aluminum work most. If you already own a machine that runs steel well, a flux core aluminum setup can be an alternative path for bigger aluminum sections, and our aluminum boat welding guide shows what good aluminum work looks like in a real application.

A Practice Plan, Realistic Timelines, and Where to Go Next

Welding punishes casual practice and rewards boring repetition. Ten hours of wandering around the machine teaches you very little. Ten hours of making the same joint over and over, changing one thing at a time and recording the result teaches you a great deal. Here is a four-week plan for the bench.

Week	Focus	What You Should End Up With
1	Setup and safety, flat beads on 1/4-inch scrap	A machine that runs consistently and a repeatable flat bead you can measure
2	Butt joints, stringers, travel speed and heat control	Consistent penetration and a bead of the same width every time
3	Fillet welds, horizontal and vertical work, stringers and weaving	Confidence off the flat position and a feel for the moving puddle
4	One small project	A finished part with joints you cannot cheat around

Week 1: Get the machine right before you chase the bead

Start with setup and safety, not production welds. Hang the helmet, dress for it, run the gas and check for leaks, load the wire, set the drive tension, and clamp the work directly to the plate. Then run flat beads on 1/4-inch scrap steel. Do a dozen of them and do not try to make them pretty yet. Notice the arc sound, the bead width, how far the puddle travels, and how hard you worked to hold the gun still.

Buy consumables and gas before you need them, and keep a spare contact tip, nozzle, and liner on hand so a bad one never becomes an excuse to stop. A welding supply buyer’s guide covers what to buy and what to skip.

Weeks 2 and 3: Joints, positions, and the puddle

Week 2 is butt joints and stringer beads, with travel speed and heat control as the two variables you are tuning. Week 3 adds fillet welds and takes you out of position, horizontal and vertical, where gravity works against you and where most beginners discover how much of their “control” was really flat-position luck. Add weaving, but only after stringers are consistent. Our guide to all-position welding consumables explains why filler behavior changes by position.

Week 4: Build something

A steel shelf bracket, a trailer hitch component, a workbench frame, or a smoker. Pick one that forces a T-joint, a corner joint, and a joint you have to hold up while you weld it. Projects teach what isolated coupons hide: fit-up gaps, awkward positions, and running out of wire halfway through.

What “Getting Good” Actually Takes

Be realistic about the timeline. A beginner can lay down a decent 1/8-inch fillet within a dozen or two practice beads. A clean, repeatable, code-quality fillet that passes inspection is a different story, typically dozens of hours of repetition away. Almost nobody is born knowing how to hold a puddle still.

Where to Go Next

Eventually you will want to read a weld symbol, understand a welding procedure specification, and work toward certification. A WPS documents the variables behind a qualified joint: process, filler metal, shielding gas, positions, amperage, voltage, and technique. Bench habits are not a WPS until someone writes them down and proves them.

For the formal side, the American Welding Society publishes more than 350 standards on welding practices and procedures. The one most structural steel shops care about is AWS D1.1, the structural steel code. D1.2 covers aluminum and D1.6 covers stainless steel. If you plan to work in aluminum or stainless, our aluminium welding course breakdown covers those pathways.

AWS also runs the Certified Welder and Certified Welding Educator credentials, plus free welding resources for members, and those are the natural next step once your flat and horizontal work is boringly reliable.

Conclusion

MIG welding is not a talent test. It is a feedback loop: weld it, cut the coupon open, look at what happened, change one variable, weld it again. The people who improve fastest are rarely the ones with the steadiest hands. They are the ones who actually looked.

You now know what MIG welding is, what to buy, how to match wire to gas, how to set up the machine, and how to fix the defects that will show up in your first hour. The only thing left is a bead. Grab some scrap steel and run one 10-minute weld today.

Frequently Asked Questions

What does MIG welding actually stand for?

MIG stands for metal inert gas, the trade nickname for gas metal arc welding (GMAW), the formal AWS term. The process uses a continuously fed solid wire electrode and a shielding gas to fuse and join metals. European shops often use ‘MAG’ (metal active gas) for the same process when the gas blend contains CO2.

Is MIG welding hard for a complete beginner to learn?

No — MIG is widely recommended as a first arc welding process because the filler metal feeds automatically and the puddle is easy to read. The honest difficulty is not the arc, it is heat control on thin material and keeping a consistent travel speed. Expect a few dozen hours of practice before a fillet weld is repeatable.

What is the difference between MIG welding and TIG welding?

MIG feeds filler wire automatically and uses a shielding gas, making it fast and well suited to production and fabrication work. TIG uses a torch and a separate filler rod added by hand, giving superior control and a cleaner bead but at a much slower pace. TIG also welds thinner and more delicate materials more easily.

What wire and gas do I need for mild steel?

For most home and shop steel work, use ER70S-6 solid wire with a 75/25 argon-CO2 blend (often called C25). Pure CO2 is cheaper and penetrates well but produces noticeably more spatter. For outdoor or dirty-condition work, E71T-GS self-shielded flux-cored wire is a good alternative because it needs no gas cylinder at all.

What settings should I start with on 1/8-inch steel?

A reasonable starting point with .035 ER70S-6 and a 75/25 blend is roughly 18-19 volts with wire feed speed in the 250-300 ipm range, then tune from there. Treat manufacturer charts such as Miller’s MIG weld setting calculator as your reference, and remember that a welding procedure specification always outranks a generic chart.

Do I need shielding gas to MIG weld?

Yes, for solid-wire MIG — the gas is what keeps oxygen and moisture off the molten pool, and without adequate shielding you get porosity. The only exception is self-shielded flux-cored wire, which carries its own flux and does not need a gas cylinder. Shielding gas also makes MIG welding wind-sensitive.

Why is my MIG weld full of holes and bubbles?

That is porosity, and it almost always comes from gas contamination rather than a bad machine setting. Clean the steel with a stainless brush wheel and a solvent wipe before welding, check the cylinder, regulator, and flowmeter for leaks, confirm the flow rate is in range, and shield the joint from wind.

Can I MIG weld aluminum and stainless steel?

Yes, but each needs its own consumables. Aluminum uses 100% argon, ER4043 or ER5356 wire, a spool gun or aluminum-rated liner, and a thoroughly cleaned joint. Stainless uses ER308L wire with a tri-mix gas, and produces hexavalent chromium in the fume, so extraction matters more than usual.

Is it safe to weld indoors in a garage?

It can be, but OSHA requires mechanical ventilation of at least 2,000 cubic feet per minute per welder in spaces under 10,000 cubic feet per welder, in rooms with ceilings under 16 feet, and in confined spaces. In practice that means a fume extractor or a good canopy hood, plus fire precautions and a fire watch when combustibles are within 35 feet.

Do I need a welding procedure specification as a hobbyist?

Not legally for most personal work, but it is the fastest way to learn what actually matters — filler metal, gas, positions, amperage, voltage, and technique. If you ever plan to code work, sell fabricated structures, or work for a company, the WPS and a qualified welder performance test become mandatory through AWS and ASME requirements.