How to TIG Weld: A Step-by-Step Beginner’s Guide

A fabricator spends an afternoon TIG welding a stainless handrail bracket and comes away with three ugly, porous beads that flake off a file. The metal was clean, the machine was new, the gas was on — and the weld still failed. The problem was not the welder’s nerve but a stack of small, learnable decisions: the wrong tungsten for the polarity, gas flow set by guesswork, and amperage applied with no system behind it. TIG welding is one of those skills that looks like witchcraft right up until someone explains what the arc is actually doing.

What TIG Welding Actually Is (and Why It Looks Like Magic)

TIG welding is Gas Tungsten Arc Welding, which the American Welding Society defines as an arc welding process that uses an arc between a non-consumable tungsten electrode and the weld pool, uses a shielding gas, and applies no pressure to the joint. That one sentence contains the whole trick, and once you see the logic inside it, the magic evaporates.

Three things happen at once. The tungsten conducts the current and holds the arc without being consumed, which is why it is called non-consumable. The shielding gas floods the area with argon or helium so oxygen and nitrogen cannot reach the molten pool. And the filler rod is added by hand, only when the welder decides it is needed. Nothing pushes the filler into the puddle. You do.

That last point explains both the beauty and the frustration of TIG. Because you control how much filler enters the puddle, and because you control arc length and heat input with a foot pedal, the bead comes out clean, narrow, and virtually spatter-free. But Haynes International names the major drawback plainly: deposition rate. Manual GTAW is slow. It is chosen for precise heat control, thin base metal, and root passes, not for filling a tank in an afternoon.

One naming note that trips people up. The official AWS term is GTAW, and the recommended practice document for the process is AWS C5.5. “TIG” is the trade nickname, a slight misnomer that simply outlasted the industry. The gas is not always inert either: argon and helium are inert while CO2 is not, and TIG is rarely run on CO2 anyway. Electrode selection and preparation are covered separately under AWS A5.12 and A5.12M.

The four moving parts every TIG weld depends on

Component	What it actually does
Power source	Supplies current. DC straight polarity for most work, AC for aluminum and magnesium, plus high-frequency non-contact arc starting.
Torch and tungsten	The torch holds the electrode in a collet and directs shielding gas through the cup. The tungsten carries the arc and must be the right type, ground correctly.
Shielding gas	A consumable. Protects the molten pool and the hot tungsten from air. Flow rate is a real setting, not an afterthought.
Filler metal	Added by hand from a rod held in the off hand, matched to the base metal. You decide how much and when.

Remove any one of those four and the weld does not happen.

Why the bead looks the way it does

A TIG arc is not a spray of droplets. It is a sustained column of ionized gas between the tungsten tip and the workpiece, and the molten pool is comparatively small and calm. With no flux to boil away and no consumable wire to spatter, the bead is smooth, the edges are crisp, and there is no slag to chip off. That clean surface is why TIG is the default for stainless food equipment, brewery tanks, and visible architectural work.

The reason the bead is slow is the same reason it is good. A fabricator working a stainless handrail can hold the amperage at a level that keeps the heat tint to a thin blue line and stops the tube from sagging. MIG would lay metal faster, but also hotter and messier, and on thin-gauge stainless that difference is the whole ballgame. For the opposite side of the trade, our comparison of why SMAW still wins in the field makes the case for stick, which has the same heat-and-simplicity appeal outdoors that TIG cannot match.

Where TIG genuinely wins

• Thin-gauge stainless, from sheet and tubing up to heavier pressure work, where heat input has to stay low.
• Aluminum and magnesium, where AC cleans the oxide while the electrode-negative phase does the penetrating.
• Tube and pipe root passes and fit-up-critical joints, where filler placement must be precise. Aerospace and pressure-vessel work relies on this control, as detailed in our aerospace TIG welding guide.
• Root passes on thicker sections, where a MIG gun would melt the joint edges before the root could be made.
• Repair work, where a small, precise puddle beats a big fast one.
• Visible finish work, where the bead is the product.

The vocabulary you will meet in this guide

A few terms carry most of the meaning, so get them straight now.

• Arc — the glowing column of ionized gas.
• Puddle — the small pool of molten metal you are manipulating.
• Filler rod — the wire you feed in by hand.
• Cup (nozzle or gas cup) — the ceramic or metal piece on the torch that shapes and delivers the gas.
• Tungsten — the electrode.
• Polarity — which way current flows. DCEN, direct current electrode negative, is standard for TIG on steel, stainless, and nickel.
• AC balance — the ratio of electrode-negative to electrode-positive time, and what controls oxide cleaning on aluminum.
• Post-flow — the delay after you release the foot pedal, during which gas keeps flowing and the tungsten keeps cooling.

What to have in hand before you strike an arc

You need a TIG-capable power source, a torch with a collet sized to your tungsten, a cup, the correct electrode, a cylinder of welding-grade argon with a regulator and flow meter, filler rod matched to your base metal, a ground clamp, and PPE including an auto-darkening helmet. If you have not already chosen a machine, our welding equipment guide walks through what matters and what is optional. Filler selection deserves its own reading too, including rod diameter and handling, covered in the all position welding rod guide.

Finally, set expectations honestly. TIG is a multi-session skill. The first hour on 16-gauge mild steel can feel like pouring water from a moving bucket, while the fabricator welding a stainless handrail may have spent months getting there. The difference is not talent but a repeatable set of small decisions, which is exactly what the rest of this guide breaks down for you.

Choosing and Setting Up the Machine, Torch, and Workstation

The hardware you pick before striking a first arc shapes every weld you lay down. Get it right and your first afternoon is productive. Get it wrong and you spend the afternoon fixing the machine.

What a TIG-Capable Power Source Must Offer

Not every welder that accepts a TIG torch is a TIG machine. Shop for these in rough order of importance:

• DC straight polarity (DCEN). The baseline for steel, stainless, nickel alloys and titanium, giving deep penetration and a clean bead.
• AC output. Non-negotiable for aluminum or magnesium: the electrode-negative half melts the metal, the electrode-positive half breaks up the oxide film.
• High-frequency, non-contact arc start. Starting without touching the work protects the tungsten tip and removes the contamination of scratching the electrode on the plate.
• Gas pre-flow and post-flow. Pre-flow clears air from the torch and cup before the arc; post-flow keeps gas flowing after you break it, shielding the cooling puddle.
• Remote amperage control by foot pedal. Close to mandatory for TIG: heat input is set by how hard you press, and TIG is modulation, not a fixed number.

Miller’s Multimatic 220 AC/DC TIG control panel shows a modern feature set: AC frequency 60 to 150 Hz (Pro-Set 120 Hz), AC balance 60 to 80% electrode negative (Pro-Set 75%), DIG arc force control, DC pulse from OFF to 150 pulses per second (Pro-Set 100 PPS), and TIG post-flow from AUTO to 25 seconds, minimum 8.

Inverter vs. Conventional, and Why the Waveform Matters

Traditional TIG machines were large transformers: heavy, hot and slow to modulate, so heat control felt like steering a bus. Modern inverters are lighter, more responsive and far more efficient.

The bigger revolution came on aluminium. Conventional AC machines produced a sine wave that spreads cleaning action thinly across the cycle. Square-wave inverters hold the electrode-positive cleaning phase longer and concentrate arc energy, turning AC TIG on aluminium from a test of patience into a routine job.

Know Your Torch

A TIG torch is simpler than it looks. The body holds everything and takes the heat. Inside sits the collet, a sleeve gripping the tungsten, with a threaded collet cap holding it in place. The gas cup at the front, ceramic or graphite, shields the arc and directs the gas.

Cup size matters more than beginners expect. A #5 cup on 3/32 inch material is plenty; a #8 or #10 on 1/4 inch stainless is not optional. Linde recommends the largest practical gas cup and a torch with a gas lens, which stabilises gas flow and gives optimum shielding coverage over a wider area.

Keep the nozzle close to the work, roughly 1/8 to 1/4 inch of cup-to-work distance, and stay under about 1/2 inch, which minimises surface discoloration on stainless. Pull the cup back and ordinary air dilutes the shield.

Building the Workstation

Put the ground clamp directly on the workpiece, which on a small project is simply correct practice. But there is a diagnostic here: clamp to one side of a T-joint and, if the arc wanders or the bead looks wrong, suspect the ground path. Move the clamp to the far side of the joint and the problem often disappears. Clamping a T-joint is not good practice, but it is a useful fault-finding tool.

Next comes fixturing and heat sinking. Clamp the work so the joint cannot move, and add copper or steel heat sinks on thin material so the heat goes somewhere other than into your part. A soapstone-saturated or soap-filled surface gives you a slick, non-marring plate for small parts. Rig the assembly so shrinkage pull does not fight your fixturing: distortion you fight is distortion you still have.

Get the gas side right too: a proper oxygen regulator with a flow meter, rated hoses that do not leak, and for high-integrity work something better than a basic rubber diaphragm setup. Linde notes that a high-integrity delivery system and a high-integrity line from the flow meter to the machine’s gas solenoid are worth the money, because rubber hoses may leak and slow the shield. Our equipment guide covers the surrounding gear.

Consumables You Will Actually Buy

Plan for a small shelf: O-rings, electrode caps, collets sized to each tungsten diameter, a spare cup in a couple of sizes, a flow meter with a proper O2 regulator, and hose. Miller’s AUTO post-flow is sensible machine logic: the gas timer comes from the maximum amperage of each cycle (maximum amperage divided by 10), minimum 8 seconds, so a light bead gets a shorter purge than a heavy one.

A Sensible First Purchase

For a beginner, a 200-amp inverter with AC/DC capability, 2% lanthanated tungsten and a foot pedal is a baseline that will not need replacing. Miller’s documentation notes that pure tungsten (green) is not recommended for inverters, and that electrodes should be sharpened for both AC and DC with a straight, longitudinal grind. If aluminium is in your plans, AC capability is non-negotiable. Our aluminum MIG welding guide covers the other route for lighter aluminium work.

Tungsten Electrodes: Picking, Grinding, and Preparing the Right Tip

The tungsten is what gives your TIG arc its focus. It’s not filler metal, but it conducts current and shapes how your puddle behaves. Get the wrong type, or grind it poorly, and you’ll fight a wandering arc no matter how dialed your settings are. Get it right, and the puddle will stay exactly where you want it.

Know Your Classifications

Tungsten electrodes fall under AWS A5.12 and ISO 6848. Each alloy, or dopant, affects heat resistance, arc starting, and tip stability.

Type	AWS	ISO	Color Code
Pure tungsten	EWP	WP	Green
2% ceriated	EWCe-2	WC20	Orange or gray
1% lanthanated	EWLa-1	WL10	Black
1.5% lanthanated	EWLa-1.5	WL15	Gold
2% lanthanated	EWLa-2	WL20	Blue or sky blue
1% thoriated	EWTh-1	WT10	Yellow
2% thoriated	EWTh-2	WT20	Red
Zirconiated	EWZr	WZ	Brown or white
Rare-earth hybrid	EWG	—	Not standardized

Always trust the printed classification over the color code. Some manufacturers vary their colors, and a few are shared between alloys.

Which Electrode For Which Job

Keep your selection simple based off of polarity.

DCEN (steel, stainless, nickel alloys, and titanium): A pointed or truncated rare-earth electrode is your best bet. Lanthanated holds a sharp point well, starts cleanly, and stays stable for long runs. Ceriated is also a proven option, while pure tungsten is less efficient on DC and dulls faster.

AC (aluminum and magnesium):

• Older sine-wave or traditional square-wave machines: Use pure or zirconiated tungsten with a balled tip. The alternating polarity handles oxide removal, and the ball keeps a stable arc on these waveforms.
• Modern inverters with square wave or improved waveforms: Use lanthanated or a rare-earth hybrid with a pointed or truncated tip. As Arc-Zone’s electrode selection guidance states, these offer a tighter, more directional arc than a balled pure tungsten on these machines.

For most beginners running a modern inverter, 2% lanthanated is hard to beat. It can run both DC and AC, resists balling, and requires far less machine-specific guesswork.

Grinding: Where Most Beginners Go Wrong

A tungsten needs to be ground before use, as its tip shape changes every time it’s struck. Always use a dedicated diamond or borazon wheel for tungsten, and never share one with steel, copper, or aluminum. If you have to share, grind the tungsten first and clean the wheel after.

Grind longitudinally along the length of the electrode, not around its circumference. As Miller warns, circumferential grinding can create an uneven edge that causes a wandering arc. Keep the taper concentric to prevent the arc column from drifting off to one side.

For the grind angle, Miller specifies 15 to 30 degrees for a focused arc, while Haynes recommends a 30 to 60 degree included cone with a small flat of 0.040 to 0.060 in (1.0 to 1.5 mm) left at the point. The flat is what conducts current into the work, so don’t neglect it.

Matching Diameter To Amperage

Too small of an electrode will melt and shed at high amperage. Too large will wander and unfocus at low amperage. The current ranges below, published by Lincoln Electric, are for DCEN operation.

Diameter	Metric	Current Range (DCEN)
0.020 in	0.5 mm	5 to 20 A
0.040 in	1.0 mm	15 to 80 A
1/16 in	1.6 mm	70 to 150 A
3/32 in	2.4 mm	150 to 250 A
1/8 in	3.2 mm	250 to 400 A
5/32 in	4.0 mm	400 to 500 A
3/16 in	4.8 mm	500 to 750 A
1/4 in	6.4 mm	23 to 27 A AC reference

For most beginners, a 3/32 in lanthanated electrode will cover the majority of work. Keep a 1/16 in on hand for thin material, or a 0.040 in for tight spots where the access problems call for a much smaller electrode.

Shielding Gas and Filler Metal: The Two Supplies People Get Wrong

Ask a beginner what went wrong with a rough TIG bead and they’ll point to the machine, tungsten, or their technique. More often than not, it’s the two consumables they overlook: shielding gas and filler metal. Subtle when incorrect, both can turn an otherwise sound weld into one that’s porous, oxidized, or outright incompatible with its base material.

Argon is the Default, But Purity Matters

Pure argon is the go-to for TIG for a reason. It’s inert, heavier than air, and affordable. However, purity isn’t something to skim over. Haynes International specifies welding-grade argon at 99.996% minimum purity, and Linde recommends ultra-high purity argon, Grade 5.0 (99.999%) or better where available. Trace amounts of oxygen and nitrogen can oxidize the molten puddle and introduce hydrogen-related porosity, an issue that is especially prevalent with stainless steel.

Flow Rate: The Number You Need to Dial In

There isn’t a single flow rate that works for every weld. It will shift based off of nozzle size, arc length, joint geometry, material, and travel speed. With that being said, there are reliable starting points to work from:

• Haynes: 20–30 CFH (9–14 L/min) for 100% argon, with pure helium requiring roughly double that.
• Linde: 15–20 CFH for most TIG applications.
• General charts: 5–20 CFH for thin work, rising to 25–40 CFH for heavy stainless or aluminum sections.

Too little flow leaves the puddle exposed to air, causing oxidation, rainbow discoloration, and porosity. Too much flow is just as detrimental, creating turbulence that aspirates surrounding air into the arc column. This can lead to a noisy, wandering arc and oxidation despite a seemingly flooded cup.

For timing, Linde recommends pre-flow and post-flow of roughly one second for every 10 amps when your power source allows for it. Out of the two, post-flow is the most important, as it protects a cooling bead from oxidizing once the arc is extinguished.

When to Leave Plain Argon Behind

While argon will cover the vast majority of work, some joints benefit from blends:

• Thicker sections: For material over 1/8 in, an argon/helium blend can drastically improve penetration and travel speed, however, amperage must be reduced when switching to helium mixes.
• Stainless over 1/16 in: Some gas selector charts call for 95 Ar-5 H, as the small hydrogen addition increases heat input, improves bead contour, and minimizes undercutting.
• Regulator compatibility: Hydrogen mixes under 10% H2 require a CGA 350 regulator, whilst CGA 580 is used for pure argon. These fittings are not interchangeable, so always verify what your supplier has delivered. Avoid hydrogen mixes for stainless-to-carbon steel joints entirely.

For cylinder safety, always utilize a regulator, flow meter, and undamaged hoses. Linde also recommends a high flow moisture trap and, for central lines, an oxygen trap. Never substitute oxygen or any non-inert gas for TIG, as this creates a genuine ignition and explosion risk.

Filler Metal: Match the Alloy First

Filler isn’t a one-size-fits-all rod. Compatibility with the base metal is non-negotiable, as the wrong alloy creates a dissimilar joint with its own set of weaknesses.

Base Material	Common TIG Filler
Mild Steel	ER70S-6
Stainless (304 / 316)	ER308L, ER316L
Stainless to Carbon Steel	ER309L
Aluminium	ER4043, ER5356, ER1100

Linde recommends matching filler per AWS or CWB guidelines, specifically noting E309 filler for stainless-to-steel joints. Per AWS, filler must be dry, free of oxides, grease, or foreign matter, and compatible with the base alloy. Damp filler should always be dried prior to use, a precaution that is paramount for stainless to prevent hydrogen-induced cracking.

Diameter is just as crucial. Thin-gauge work between 30 and 60 amps calls for 3/32 in rod, whilst heavier plate and higher amperage is better suited to 1/8 in. If the rod is too thick for the puddle, it will swamp it and strip all control away from you.

Adding Filler Without Ruining the Bead

The golden rule is simple: add filler to the leading edge of the puddle, not the arc itself. Utilize a “dip, move, dip” motion, dipping the rod tip into the pool before retracting it. Keep that tip inside of the shielding gas envelope at all times, and never let it touch the tungsten. Even the slightest contact can contaminate the electrode, ruining both it and your bead.

Lastly, for multi-pass welds, inter-pass cleaning with a 300 series stainless steel brush is highly recommended to remove any oxide between passes. For a broader breakdown of rod selection, our filler metal and welding rod guide covers the rest of the catalogue.

The Step-by-Step Technique: From Clean Steel to a Sound Bead

Each step protects the one after it, and skipping ahead is how beginners end up with porous beads nobody can explain.

Step 1: Prepare the Joint

Mill scale, rust, paint, oil, grease and solvent residue have to go. OSHA advises cleaning welding surfaces of coatings that could create toxic exposure, such as solvent residue and paint. Clean the joint with a file, flap disc or mill, feather the edge, degrease with acetone or a metal cleaner and wipe with a lint-free cloth. Skip chlorinated or aerosol brake cleaners; heat flashes residue into fumes. Aluminum degreases differently than steel, so a dedicated aluminum cleaner for welding is worth owning.

Step 2: Mount, Clamp and Ground

Clamp the workpiece so it cannot move and think about where the heat will go. Heavy plate wants a heavy ground clamp. Keep the clamp off the joint you are welding, because current running through the joint is a fault-finding tool.

When a weld misbehaves, clamp your ground onto the joint and try again. If the problem disappears, current is bypassing your work. If nothing changes, the fault is in the machine, consumables or technique. Clamp to clean bare metal only.

Step 3: Set the Gas and Check for Leaks

Open the argon valve and let it flow for a minute. Listen along the torch hose, check the connections and read the flow meter, then set the flow rate, typically 15 to 20 CFH. Find leaks now, because a leak starves the arc of shielding. Keep the cylinder upright and secured.

Step 4: Insert and Grind the Tungsten

Grind the electrode, slide it into the collet and tighten it with the collet tool. A loose collet causes a wandering arc and erratic shielding. Set the tip so it projects roughly 1/4 inch beyond the cup: too far out the arc wanders, too close the cup gets hot enough to melt. The Arc Zone guide to selecting tungsten electrodes covers tip styles.

Step 5: Body Position and a Dry Run

The Step-by-Step Technique: From Clean Steel to a Sound Bead

Each step protects the one after it, and skipping ahead is how beginners end up with porous beads nobody can explain.

Step 1: Prepare the Joint

Mill scale, rust, paint, oil, grease and solvent residue have to go. OSHA advises cleaning welding surfaces of coatings that could create toxic exposure, such as solvent residue and paint. Clean the joint with a file, flap disc or mill, feather the edge, degrease with acetone or a metal cleaner and wipe with a lint-free cloth. Skip chlorinated or aerosol brake cleaners; heat flashes residue into fumes. Aluminum degreases differently than steel, so a dedicated aluminum cleaner for welding is worth owning.

Step 2: Mount, Clamp and Ground

Clamp the workpiece so it cannot move and think about where the heat will go. Heavy plate wants a heavy ground clamp. Keep the clamp off the joint you are welding, because current running through the joint is a fault-finding tool.

When a weld misbehaves, clamp your ground onto the joint and try again. If the problem disappears, current is bypassing your work. If nothing changes, the fault is in the machine, consumables or technique. Clamp to clean bare metal only.

Step 3: Set the Gas and Check for Leaks

Open the argon valve and let it flow for a minute. Listen along the torch hose, check the connections and read the flow meter, then set the flow rate, typically 15 to 20 CFH. Find leaks now, because a leak starves the arc of shielding. Keep the cylinder upright and secured.

Step 4: Insert and Grind the Tungsten

Grind the electrode, slide it into the collet and tighten it with the collet tool. A loose collet causes a wandering arc and erratic shielding. Set the tip so it projects roughly 1/4 inch beyond the cup: too far out the arc wanders, too close the cup gets hot enough to melt. The Arc Zone guide to selecting tungsten electrodes covers tip styles.

Step 5: Body Position and a Dry Run

Sit or stand so you can see the puddle, the joint and the tungsten tip without craning your neck. A cramped position causes a wandering torch and an inconsistent bead long before your hands are the problem. Then run the torch cold along the joint, noting your start and end points and how you will handle the filler rod.

Step 6: Strike the Arc

Bring the electrode to roughly 1/8 inch above the work and start the machine using high-frequency start or lift-arc if you have one. Never touch the metal to start; it creates a dead short and a crater at the head of the bead. With a modern inverter the arc strikes on its own.

Step 7: Establish the Puddle Before You Add Filler

This is the most important habit in the process. Melt the base metal, hold the puddle steady and confirm penetration before touching filler.

That step is the specific advantage GTAW has over GMAW. In MIG or flux core work, filler fed on a trigger press can arrive before the base metal is melted, giving cold starts and lack of fusion. In TIG you control the order: puddle first, heat input second, filler last.

Quick Note: If your bead is lumpy and dull instead of narrow and bright, you are adding too much filler. Filler is a cooling agent in the molten pool. Per The Fabricator, more filler per dab gives a more pronounced stacked-dimes profile, less a smoother bead.

Step 8: Add Filler with a Dip Rhythm

Touch the filler rod to the leading edge of the puddle, pull it back out, move the torch, repeat. That dip-move-dip rhythm keeps the heat moving and the bead consistent. Haynes International recommends adding filler carefully at the leading edge of the pool, never touching the tungsten electrode, and keeping the filler tip under the shielding gas.

Never let the rod kiss the tungsten; it ruins the tip and contaminates the pool. If you cannot see the puddle, check your cup size and head position.

Step 9: Travel Angle and Work Angle

Haynes International recommends holding the torch essentially perpendicular to the workpiece, at a 90 degree work angle with only a slight 0 to 5 degree travel angle. A large drag angle draws air into the shielding gas and contaminates the weld. Your torch points down into the joint and stays there.

Step 10: Finish Cleanly

At the end of the bead, taper off the foot pedal rather than snapping it off, filling the crater where porosity likes to hide. Leave the torch in place through the post-flow timer so the hot metal stays covered by gas as it cools. Linde guidance on improving TIG results notes that with proper shielding the as-deposited metal comes out bright and shiny.

Step 11: Inspect and Clean

Let the bead cool, then scrub it with a dedicated stainless brush to remove the oxide film. TIG produces no slag, so there is nothing to chip away, just a light brush and a rinse.

Short Note: TIG is quiet. No crackle, no spatter flying, no slag to tap off. That silence is why beginners lean over the arc. The UV and infrared radiation is just as real as on a loud MIG machine.

Why Pulse TIG Is Worth Learning

Once the basics are solid, pulsed TIG is a real training tool. Miller’s MultiMatic TIG pulse defaults to 100 pulses per second with 40 percent peak time and background amperage at 25 percent of peak amperage. Setting it to 1 to 10 pulses per second gives a slow ripple you can watch, making filler timing easier to learn and giving tight control on thin material where a continuous arc burns through.

Work through these eleven steps on a scrap coupon and the bead on your handrail bracket stops being a question mark. It becomes something you repeat on purpose.

Settings That Matter: Amperage, Polarity, AC Balance, Frequency, and Pulse

What beginners want is a settings chart. What they need is a system, so they can reason out an answer when the chart misses their joint. TIG responds predictably once you know what each control does.

Amperage: Start With Thickness, Then Adjust

The classic rule of thumb for GTAW is one amp per 0.001 inch of thickness, so 1/8 inch base material calls for roughly 125 amps. The rule bends above roughly 1/4 inch: thick steel does not absorb proportionally more energy, it just takes longer to heat through. That is why 3/8 inch welds fine on a 280-amp machine, and a 200-amp source covers most shop work.

Joint geometry trips up more beginners than anything else. A butt joint has two surfaces absorbing heat, a T-joint has three, because the vertical member steals energy from the puddle. The same 1/8 inch plate might run at 100 amps in a butt but want 130 amps as a T-joint for equal penetration. A narrow, shallow bead means you underheated the joint.

Quick Note: Unsure whether you need more amps or more time? Add heat before filler. More filler on an underheated puddle makes a fat, cold-looking bead that grinds poorly and lacks root fusion.

Polarity: DCEN for Almost Everything

Most TIG runs on DCEN, tungsten negative and workpiece positive. That gives the deepest penetration of any polarity and keeps heat in the workpiece. Use DCEN for carbon steel, stainless, nickel alloys and titanium without exception. Linde notes that direct current straight polarity should be used whenever possible, and that DCEP may occasionally serve very thin sections under 1/16 inch, where extra heat on the work melts the material without excessive penetration.

AC for Aluminum: The Cleaning Cycle

Aluminum and magnesium demand alternating current. Aluminum oxide melts at roughly three times the melting temperature of the base metal, so neither a flame nor a DC arc can clear it, and the layer re-forms the instant it is cleaned. AC breaks the oxide film during the electrode-positive half of the cycle and drives penetration during the electrode-negative half. Modern inverters let you set each half independently: raise the EN amps and lower the EP amps for penetration with gentler cleaning on thin aluminum. Our aluminum MIG welding guide covers the competing process, and that oxide problem keeps TIG the go-to for aluminum.

AC Balance: The Cleaning-to-Penetration Dial

Balance is the ratio of electrode-negative time to electrode-positive time. Miller’s Pro-Set factory value is 75% EN, adjustable from 60% to 80%. Drift too far toward EN and cleaning suffers; the puddle fills with floating

Balance is the ratio of electrode-negative time to electrode-positive time. Miller’s Pro-Set factory value is 75% EN, adjustable from 60% to 80%. Drift too far toward EN and cleaning suffers; the puddle fills with floating black flecks, a defect welders call peppering. Miller’s guidance is straightforward: when you see those spots, turn the balance down until the puddle runs clear.

The tradeoff is tungsten heat. More EP time gives the electrode more to do, so the tip balls back faster and tungsten life drops, while more EN time tightens the arc and improves penetration. Most aluminum work sits between 65% and 75% EN, and stainless on AC wants higher EN still.

Frequency: Shaping the Arc Cone

Frequency controls how tightly the arc column focuses. Older GTAW machines ran at 60 Hz; modern equipment is preset to 120 Hz. Higher frequency means a tighter column and better directional control in narrow gaps or near a wall. The Fabricator recommends 150 to 250 Hz on thin material needing accurate placement, 80 to 90 Hz for a wider cone on outside corner joints, and 80 to 120 Hz for 3/8 inch and thicker, where a broader bead profile fills better.

Pulsed TIG and the Other Heat Levers

Pulsed TIG cycles rapidly between a peak current and a background current, keeping the puddle smaller and heat input lower. That is why it is standard for thin stainless, where it limits distortion and, as Linde points out, can improve surface color match and corrosion resistance. Miller’s convention sets background at 25% of peak current with peak time at 40% of the cycle. Pulsing also teaches good filler timing, so welders use it as training.

Arc force, which Miller calls DIG on its Multimate machines, adds amperage during short-arc conditions to keep the arc stable close to the workpiece, adjustable from OFF to 99%. Travel speed is the second heat lever: slower travel concentrates heat and deepens the bead, faster travel spreads it and flattens the profile.

Voltage is an outcome, not a knob. You do not set voltage in TIG; arc voltage follows amperage, gas, tungsten tip and arc length. If the bead is wrong, change amperage, travel speed or technique rather than hunting for a voltage setting that does not exist.

Setting	Typical Value	When to Adjust
Amperage	1 amp per 0.001 in. of thickness	More for T-joints and deep grooves, less for thin stock
Polarity	DCEN for steel, stainless, nickel, titanium	AC for aluminum and magnesium
AC balance	75% EN, adjustable 60 to 80%	Down for peppering, up for penetration
AC frequency	120 Hz preset, adjustable 60 to 150 Hz	80 to 90 Hz wide cone, 150 to 250 Hz thin

Short Note: Charts from Haynes International and AWS A5.12 electrode standards are good starting points, but treat each as a hypothesis. Weld a coupon, break it, and write down what actually happened.

Start with your machine’s presets, dial amperage by joint geometry, and leave frequency alone until the basics are automatic.

Same Process, Different Metals: Steel, Stainless, Aluminum, and Thin Gauge

The arc does not know what you are welding. A tungsten holds a cone of plasma, gas shields the puddle, and filler goes in at the melt edge. Every alloy has its own rules for gas, polarity, electrode, filler and heat input.

Mild and Low-Alloy Steel: The Baseline

Steel forgives, so start there. Use DCEN, a lanthanated or ceriated electrode with a pointed or truncated tip, ER70S-6 filler rod and pure argon. Prep is non-negotiable: remove mill scale, rust, paint and oil. Mill scale floats up through the puddle and spits out as porosity, so grind to bright metal.

Typical GTAW parameters for plain carbon steel:

Joint	Amperage	Tungsten	Filler	Gas cup	Argon flow
1/16 in. butt	60-80 amps (70-100 amps for a beefier setup)	1/16 in.	1/16 in.	No. 4/5/6	15 CFH at 20 psi
1/8 in. butt	125-145 amps	3/32 in.	1/8 in.	No. 6/7	17 CFH
3/16 in. butt	190-220 amps	1/8 in.	1/8 in.	No. 7/8	21 CFH (Ar/He blend common)

Starting points, not commandments: a fillet carries more heat than a butt of the same thickness, so trim the amperage or slow down.

On thin gauge, the 1 amp per 0.001 inch rule keeps heat in check. Use the smallest tungsten that will fuse the joint, keep the arc tight, pulse if the puddle runs away, and back the work with a copper strip so the root does not drop.

Stainless Steel: Heat Is the Enemy

Stainless welds beautifully with TIG, the classic benchmark for the process. Its two vulnerabilities, sensitization and distortion, both come from heat. Keep the bead narrow, interpass temperature low, and move.

Linde lists argon for stainless under 1/16 in. and 95 Ar-5 H over 1/16 in., noting that argon with hydrogen raises heat input, improves bead contour at lower gas flows, improves puddle wetting and minimizes undercutting. More heat also means more distortion and sensitization risk, so minimize heat input while holding penetration and cool thin sections fast to protect corrosion resistance.

For anything that sees moisture or food service, back-purge: Haynes International recommends a back-purge at the root side of the joint with welding-grade argon at 5-10 CFH (2-5 L/min) and copper backing bars to control root bead shape. The copper bar shapes the root and wicks heat away so it does not sink.

Clean between passes with a dedicated stainless brush, never your steel brush. Those oxide flakes and iron particles are why a part that looked perfect on the bench rusts weeks later. Expect heat tint, then pickle or passivate.

Quick Note: Heat sinks and clamp spacing matter most on thin stainless. Put copper or aluminum clamps either side of the joint, back from the weld, over a heavier fixture.

Aluminum and Magnesium: AC, and a Clean Start

Aluminum is why TIG exists in modern shops. It conducts heat roughly five times better than steel and carries an oxide whose melting point is about three times that of the base alloy. You cannot melt your way through aluminum oxide, so clean it mechanically and keep it clean electrically.

Settings shift with the machine. On older sine-wave or square-wave sources, use pure or zirconiated tungsten with a balled tip; on modern inverters, use lanthanated or rare-earth with a pointed or truncated tip. Gas is argon, and filler is ER4043, ER5356 or ER1100, stored dry and used clean. Prep matters: a dedicated aluminum cleaner and acetone degreasing are critical, because aluminum holds grease in its oxide layer and welding over it produces a shower of porosity.

Heat input runs higher than the 1 amp per 0.001 inch rule suggests because of the conductivity, so travel slower and expect a wider, flatter bead. TIG beats aluminum MIG setups because GTAW avoids the GMAW cold-start problem: no wire feed means no cold slug dropped into a puddle too cool to fuse it.

Titanium, Copper, Brass, and Nickel Alloys

Titanium demands 100 percent argon at purity, full gas coverage including back purge, and ruthless contamination control. It will weld to anything you touched thirty seconds earlier, so dedicated stainless brushes, gloves and tooling are mandatory.

Nickel-base alloys run DCEN, usually a thoriated electrode for arc stability, and manual travel of 4-6 inches per minute (100-150 mm/min), slower than carbon or stainless steel. Haynes International’s typical manual GTAW parameters for nickel-base alloys list 15-75 amps for 0.030-0.062 inch material, 50-125 amps for 0.062-0.125 inch, 100-175 amps for 0.125-0.250 inch and 125-200 amps above 0.250 inch, with arc voltage of 9-15 V for thin sections and 12-18 V for thicker. Thoriated tungsten means local exhaust ventilation when you grind it.

Copper and brass weld well with DCEN, though copper is greedy for heat and its mirror surface hides defects. Marine aluminum work follows the aluminum rules with more care, since saltwater punishes porosity and weak root passes.

Tube and Pipe: Where TIG Earns Its Keep

Tube welding is why many fabricators own a TIG machine: the root pass is a fusion problem in three dimensions. Add filler without touching the tungsten, and back purge anything with a service fluid behind it.

Repair Work Versus Production Parts

On repairs, slow down and inspect before you overlay; on production parts, follow a written procedure and a qualified inspector.

Short Note: AWS guidance on aluminum TIG insists that filler metal be dry and free of oxides, grease or foreign matter, and that the process has real advantages for manual and automatic welding. The aerospace TIG welding standards overview shows the same rules enforced in regulated work.

Common Mistakes, Bad Welds, and How to Diagnose Them

A bad TIG bead rarely points to one giant error. It points to a small decision that slipped through. Work backward from the symptom to its root cause, then fix it on the next pass.

Gas and Contamination Issues

The most deceptive faults come from shielding. According to Haynes International, even a small amount of air can compromise the protective shielding and cause weld metal oxidation, discoloration and porosity. Sources include air movement from fans, cooling systems and drafts, or air leaking in through a loose gas cup or other torch parts.

Porosity appears as tiny pinholes throughout the bead. Kill nearby fans, confirm the gas cup is tight, inspect the torch for leaks and make sure the base metal is clean. For cylinder setups, Linde recommends a high-integrity gas delivery system over a standard rubber diaphragm regulator and flowmeter, plus a high-integrity line from flowmeter to solenoid, since conventional rubber hoses can leak.

Contaminated filler is just as guilty. Keep rods in a clean, dry container, and on finicky pieces needing aluminum cleaner for welding style prep, do not skip degreasing.

Tungsten, Arc Stability, and Starts

Your electrode is the heart of arc control. Per Arc-Zone, the most common tungsten selection mistakes are:

• Pure tungsten where rare earth is better suited
• Wrong electrode diameter for the amperage
• Thoriated tungsten without proper dust control
• A balled tip on a modern inverter application
• A contaminated grinding wheel
• Ignoring power source recommendations
• Changing tungsten type without updating the welding procedure

These show up as tungsten contamination, a wandering arc, or poor starts. The two biggest culprits for wandering and inconsistent starts are pure tungsten on modern inverter applications and a contaminated grinding wheel. A loose collet, dipping the tungsten into the puddle, or an oversized balled tip can also shed tungsten into the weld, leaving hard, brittle inclusions. Fix it by grinding longitudinally on a tungsten-only wheel, using the correct diameter and type for your machine and material, and keeping tip projection consistent.

Quick Note: Never share your tungsten grinding wheel with mild steel or general shop grinding. Cross contamination is one of the fastest ways to destabilize a TIG arc.

Material Specific Issues

Oxide and peppering on aluminum is almost always AC balance. Floating black flecks mean balance is set too high on electrode-negative. Add more electrode-positive to increase cleaning action while still prioritizing penetration, confirm the oxide was mechanically removed, and use a dedicated aluminum brush. The Fabricator warns that aluminum is highly reflective and needs a great deal of energy to weld, so GTAW arc intensity can cause sunburn to exposed skin. A welding jacket, gloves, safety glasses and helmet are not optional, and the same precautions apply to heavier work such as alloy wheel welding.

Heat discoloration and rainbow tint on stainless comes from excess heat input, poor gas coverage, or an improper argon/hydrogen mix. Reduce amperage where possible, verify post-flow is sufficient, and back purge root passes. For high integrity stainless work, stay alert to fumes, because stainless can produce hexavalent chromium. OSHA’s Chromium (VI) standard sets a permissible exposure limit of 5 micrograms per cubic meter as an 8-hour time-weighted average, and requires feasible engineering and work practice controls as the primary means of reducing exposure.

Heat Control, Travel, and Crater Failures

Many of the ugliest beads come from heat mismanagement.

Symptom	Usual causes
Undercut	Too much heat, slow travel, wrong travel angle, dirty material
Lack of fusion and cold starts	Filler added before the puddle is established, too little heat, fast travel, poor joint prep
Burn-through and runaway puddle	No heat sink, too long an arc, pedal pinned at max amperage

Watch the end of the weld. Crater cracking and porosity at the tail come from snapping off the foot pedal instead of ramping down. Taper amperage slowly while holding the torch in place for post-flow so the puddle shrinks safely. A lumpy, irregular bead is almost always a timing issue: keep a steady torch height and a consistent dip-and-retract rhythm for filler rather than adding more rod all at once.

Short Note: Diagnose from the bead, not the machine. Before touching a setting, read the puddle history. A wandering start, a pinholed middle and a crater crack are three separate problems, and they rarely share one solution.

Pre-Weld Prevention Checklist

Run this before every weld to cut troubleshooting time:

• Metal: Remove oil, oxides and coatings with the correct cleaner for your alloy.
• Tungsten: Verify type, diameter and a clean longitudinal grind matched to your polarity and machine.
• Gas: Check for loose cups, intact hoses, adequate flow and no drafts nearby.
• Ground: Clamp directly to bare, clean metal as close to the joint as practical.
• Safety: Full PPE, especially on reflective metals that throw arc light onto unprotected skin.
• Dry run: Practice torch path and foot pedal taper with the arc off. Ten seconds here saves minutes of repairs.

With repetition these checks become muscle memory. A bad bead stops being a mystery and becomes a clue, and every clue you can read moves you closer to a clean, sound TIG weld.

Safety, Ventilation, and Choosing TIG Over the Alternatives

The Hidden Dangers of TIG Welding

While TIG welding is known for its precision and clean results, its quiet nature is one of its greatest safety traps. With very little spatter and a nearly silent arc compared to stick or flux-cored processes, it’s far too easy to forget the very real hazards at play.

Before striking your first arc, proper personal protective equipment (PPE) is non-negotiable. This means ANSI-compliant eye and face protection, an auto-darkening helmet with an adequate shade for TIG, flame-resistant clothing with no exposed skin, and leather gauntlet gloves. The biggest threat to unprotected eyes is arc eye, or photokeratitis, caused by intense UV and infrared exposure. Even a split second of looking directly at the arc can be excruciating.

Welding Fumes, Ventilation, and Exposure Limits

The more insidious hazard is welding fume. According to OSHA’s welding fact sheet, prolonged exposure to welding fume may cause lung damage and various types of cancer, including lung, larynx, and urinary tract cancers. Additionally, prolonged exposure to manganese fume can cause Parkinson’s-like symptoms.

This risk is elevated when working with stainless or chrome-containing consumables. OSHA states that chromium is converted to its hexavalent state, Cr(VI), during welding. Cr(VI) fume is highly toxic, can damage the eyes, skin, nose, throat, and lungs, and can cause cancer. For this reason, its permissible exposure limit (PEL) is 5 micrograms per cubic meter as an 8-hour time-weighted average. OSHA’s Cr(VI) standard requires employers to utilize feasible engineering and work practice controls to reach or maintain this limit before considering respiratory protection. NIOSH also considers all hexavalent chromium compounds to be occupational carcinogens.

These controls aren’t optional. A NIOSH evaluation of welding fume controls (Wallace, 1998) found that fume extraction gun systems reduced exposures by up to 83%, and process modification using pulsed arc welding instead of conventional GMAW reduced exposures by 24%. However, canopy hood systems were found to be completely ineffective, and even with controls, exposures for total fume and metals such as Cr(VI), arsenic, and manganese occasionally still exceeded ACGIH, NIOSH, and OSHA limits.

Follow a simple hierarchy: position yourself to avoid breathing the plume and stay upwind when welding outdoors (as noted by OSHA), utilize local exhaust ventilation over general ventilation when possible, and only rely on respiratory protection after engineering controls have been applied. For those grinding thoriated electrodes, Haynes International explicitly states that local exhaust ventilation should control the dust at the source, supplemented by respiratory protective equipment if necessary, with precautions for proper disposal of grinding dust.

Be especially cautious in tight areas. Argon and helium are heavier than air and can displace oxygen, leading to asphyxiation. Carbon monoxide and other hazards are also a concern in confined spaces, often requiring hot work permits under 29 CFR 1910.146. Keep in mind the broader applicable standards, including Welding, Cutting and Brazing (29 CFR 1910 Subpart Q, 1926 Subpart J, and 1915 Subpart D), Hazard Communication (29 CFR 1910.1200), Respiratory Protection (29 CFR 1910.134), and Air Contaminants (29 CFR 1910.1000, 1915.1000 and 1926.55).

Quick Note: Welding outdoors does not guarantee adequate ventilation. The plume can still be pulled directly into your breathing zone depending on your position and wind direction.

TIG vs. The Alternatives: When To Use It

No process is perfect for every job. Choosing the right one comes down to the tradeoff between control and productivity.

• TIG vs. MIG: TIG offers unmatched control, no spatter, a cleaner bead, and the ability to weld much thinner material. The downside is that it’s significantly slower and more expensive per inch than MIG.
• TIG vs. Stick (SMAW): TIG produces no slag, has far better aesthetics and control, and is ideal for precision work. However, stick welding still reigns when working outdoors or in windy conditions where gas shielding would be blown away.
• TIG vs. FCAW/MIG for Production: For high-volume work, MIG and FCAW are far more productive. Despite this, TIG remains the standard for stainless tube, aluminum, and root passes, especially within fields such as aerospace TIG welding.

This level of precision comes with accountability. For production welding, the work is governed by an approved Welding Procedure Specification (WPS), with qualification frameworks such as AWS standards and ASME Section IX qualification serving as the industry standard, not a home workshop checklist.

Affiliate Disclosure: Some product links on weldgallery.com may be affiliate links. We only recommend items when they genuinely help solve a welding problem, and any commissions do not influence our editorial guidance.

Your First Thirty Days: A Practice Plan That Actually Builds Skill

What separates beginners who improve from those who quit is rarely talent or a better machine. It takes short, frequent, deliberate sessions: thirty days of 30 to 45 minute practices, one new variable per week, taking you from “I made a bead” to one you would sign your name to.

Week One: Gear, Machine, and the Humble Bead-on-Plate

Helmet, jacket and gloves on before you strike an arc; keep the OSHA welding safety fact sheet close. Learn where everything lives: gas shutoff, amperage knobs, foot pedal, torch switch, ground clamp. Grind a 2% lanthanated tungsten to a clean taper, set your regulator, and run beads on 16 or 18 gauge mild steel, flat position, 30 to 40 amps. No filler rod this week. Your only job is to learn where the puddle goes and how big it is.

Week Two: Adding Filler

Same coupon, same flat position, now with 3/32 inch ER70S-6 filler and a repeatable dip rhythm: touch the leading edge of the puddle, move, repeat. When beads look consistent, move up to 1/8 inch plate and let heat come up toward 125 amps. Miller’s TIG pulse guidance notes that 1 to 10 pulses per second produces a distinct ripple pattern, used to time filler addition, reduce distortion and improve control.

Week Three: Joints and Heat Control

Flat beads are forgiving. Now practice fillet and butt joints in 3/32 inch and 1/8 inch material, treating the foot pedal as part of your technique rather than an on/off switch. Vary amperage mid-bead on purpose, then vary travel speed and note what changes in the bead. This is where you stop following a number and start reading the metal.

Week Four: Stainless, Then Aluminum

Stainless first, because it forgives beginners: DCEN, argon, low heat input, a stainless brush to remove heat tint between passes, and a back purge of 5 to 10 CFH for clean root color. Then aluminum, the real test: AC, balance adjusted until the floating flecks disappear, acetone for degreasing, a brush reserved for aluminum only, and dry filler kept sealed. Our guide to prepping aluminum for welding covers the cleaning side.

Practice Deliberately

Show up with a task, not just an hour. Mark a 6 inch line on the coupon to measure travel speed and consistency, and log amperage, gas flow and result. Break coupons to check penetration depth. Film the puddle with your phone: in slow motion it is the fastest way to catch a wandering torch or a rod dipping on the wrong side of the pool.

Quick Note: Linde recommends, where the power source allows, pre-flow and post-flow of roughly 1 second for every 10 amps of welding current, plus trailing shielding gas if the machine offers it. Set post-flow by amperage.

What It Will Cost

Budget for the whole kit, not just the machine:

• Entry-level AC/DC inverter TIG welder
• Argon cylinder with regulator and flow meter
• Box of 2% lanthanated tungsten
• ER70S-6 filler
• Copper back purge nozzle or kit
• Auto-darkening helmet
• Flame-resistant jacket and gauntlet gloves
• Scrap coupons

Tight budget? Buy the machine and PPE first, then add the four upgrades that matter most: a foot pedal, a gas lens, a proper ground clamp, and a second smaller cup.

Five Habits Worth More Than Talent

• Clean metal, every time.
• Tungsten matched to polarity and job.
• Right gas at right flow.
• A consistent puddle.
• Smooth travel.

When Practice Is Not Enough

Your month of practice is for your own work. Production welding and certification run on a qualified procedure, not instinct. AWS C5.5, Gas Tungsten Arc Welding, sets out the recommended practices that govern the process, and AWS A5.12/A5.12M specifies tungsten and oxide-dispersed tungsten electrodes. AWS A3.0 defines the standard welding terms in any procedure document. Want structure? Compare what an aluminium welding course covers, or how tightly aerospace TIG welding is regulated.

As The Fabricator notes, GTAW is slow, not typically used in high-production manufacturing, but often a good choice for aluminum, where productivity matters less than quality and appearance.

Back to That Bracket

The bracket from the opening scene is still weldable, and the weld is now knowable. It was never your nerve that failed, it was small decisions: wrong tungsten for the polarity, gas flow set by guesswork, amperage with no system behind it. Grind a tungsten, set your gas, and lay down one 6 inch bead on scrap.

Frequently Asked Questions

What polarity should I use for TIG welding?

Use DCEN (direct current electrode negative) for mild steel, stainless steel, nickel alloys, and titanium. Use AC (alternating current) for aluminum and magnesium, because the electrode-positive half of the cycle cleans the stubborn oxide layer while the electrode-negative half supplies penetration. DCEP is used only rarely, for very thin sections under about 1/16 inch.

How much amperage do I need for a given thickness of metal?

A useful starting rule is roughly 1 amp per 0.001 inch of thickness, so 1/8 inch material is about 125 amps and 16 gauge is in the 60-80 amp range. The rule drifts above about 1/4 inch, and joint geometry matters: a T-joint pulls heat in three directions versus two for a butt joint, so it needs more heat input. Always treat these numbers as starting points and adjust by watching the puddle.

Which tungsten should I buy for a home TIG welder?

For most beginners, a 1/16 inch lanthanated electrode (gold) is the best single choice, because it handles both AC and DC and works on modern inverter machines. Ceriated (orange/gray) is good for low-amperage DC precision work, and pure tungsten (green) with a balled tip still suits older sine-wave machines on aluminum. Avoid starting with 2% thoriated (red) unless a procedure requires it, because grinding the electrode releases low-level radioactive dust.

Why are my TIG welds full of porosity?

Porosity is nearly always a shielding problem, not a power problem. Causes include too little argon flow, too much flow (which creates turbulence and pulls air in), drafts, fans and air conditioning pulling air across the arc, a leaking gas hose or loose torch components, dirty or oily metal, and wet or contaminated filler metal. Check the flow rate, inspect the hose and torch, and clean the joint with a stainless brush and acetone before welding.

How do I stop my aluminum welds from looking dirty and speckled?

That speckling, often called peppering, comes from oxide remaining in the pool. Clean the aluminum with a dedicated stainless wire brush used only for aluminum and degrease with acetone, then turn the AC balance down so there is more electrode-positive cleaning action. Keep the arc short, use a good gas lens, and make sure your flow rate is in the 15-25 CFH range with no wind across the joint.

Is TIG better than MIG for a beginner to learn?

TIG teaches heat control and puddle control, which transfer to every other process, and it produces cleaner, more precise welds with no slag. But MIG is faster, cheaper per foot of weld, and much more forgiving on dirty shop steel. If your goal is stainless, aluminum, tube, or visible fabrication work, start with TIG; if your goal is production throughput on mild steel, learn MIG first and add TIG later.

Do I need to back-purge when TIG welding stainless steel?

For anything that matters, yes. Back-purging the root side with argon at roughly 5-10 CFH keeps the underside of the weld from oxidizing and forming a brittle, unsightly oxide layer that can become a corrosion initiation site. Use a copper backing bar for a clean root bead, and increase the back purge flow substantially for open-butt pipe work where you cannot reach the root side.

What safety gear do I really need for TIG welding?

You need an auto-darkening helmet with the correct shade for TIG, flame-resistant clothing that covers all skin, leather gauntlet gloves, safety glasses under the helmet, and a fire-resistant blanket or screen to protect nearby people from stray UV. On top of that, run local exhaust ventilation or a fume extractor gun close to the arc, and never TIG weld in a confined space without a permit and forced ventilation, because argon and helium displace oxygen.

Why does my tungsten keep balling up on aluminum?

A balled tip on AC is normal on older machines, but it should not keep growing. If it does, you are likely running too much electrode-positive balance (too much cleaning, not enough penetration), using too large an electrode for the amperage, or using pure tungsten on a modern inverter where lanthanated with a pointed or truncated tip works better. A ball larger than about 1.5 times the electrode diameter destabilizes the arc and can shed into the puddle.

Can I TIG weld galvanized or painted steel?

Grind or wire-wheel the coating back from the joint before welding, because zinc and paint residue create heavy fume and porosity. OSHA specifically advises cleaning welding surfaces of coatings that could create toxic exposure, such as solvent residue and paint. Also avoid chlorinated spray cleaners such as brake cleaner on the joint, since heat can convert the residue into toxic gases; use acetone or a dedicated metal cleaner instead.