Stick Welding Carbon Steel: Electrodes, Settings, Tips

A Saturday morning, a cracked A36 trailer bracket, one battered stick welder, and a box of 6013 rods that keep sticking to the plate like glue. That frustration is almost never about talent — it is about picking the wrong rod, the wrong amperage, and skipping the prep that carbon steel quietly demands. Stick welding carbon steel is the most forgiving and most demanding arc there is, and this guide explains exactly why.

Stick Welding Carbon Steel: The Welding Process That Never Left

Saturday morning, a cracked A36 trailer bracket clamped to the workbench, and a 225-amp stick welder that has outlived two trucks. The rod sticks, the plate spatters, and the temptation is to blame the machine or your own hands. In reality, stick welding carbon steel rewards preparation far more than talent, and the fixes are usually simpler than they look: the right electrode, the right amperage, and a joint that was cleaned before the arc ever struck.

So let’s answer the main question up front. What is stick welding carbon steel, and why does it still dominate repair, structural, and pipeline work? Stick welding is shielded metal arc welding (SMAW): a manual arc process in which a flux-covered consumable electrode strikes an arc against the workpiece, and the burning coating produces shielding gas and a slag blanket that protect the molten pool. Pair that process with plain carbon or mild steel, and you get the most widely taught, most portable, and most forgiving arc combination in the industry.

Why carbon steel is still the default

Carbon steel accounts for the large majority of welding performed worldwide. A NIOSH-published field note on welding hazards observes that most welding operations are performed on carbon and low-alloy steels, with stainless and other materials making up a comparatively small share (CDC/NIOSH). That matters practically: whatever you learn on carbon steel transfers directly to the work that actually exists in farm shops, structural fabricators, repair yards, and pipeline crews.

The genuine benefits of the process are hard to overstate:

• Portability. One machine, a stinger, a ground clamp, and a box of rods. No gas bottle to drag across a field or a jobsite.
• It tolerates dirty metal. Mill scale, light rust, and a bit of oil are far more forgiving under a stick arc than under wire feed. The flux does real cleaning work.
• All-position capability. With the right rod, you can weld flat, horizontal, vertical, and overhead, which you can read about in our All Position Welding Rod Guide: Types, Uses & Tips.
• Low equipment cost and weather tolerance. Stick runs outdoors and in wind better than almost any other arc process, because the shielding comes from the coating rather than a gas envelope.

The limitations are equally real. Deposition is slower than MIG, so large volume fills take longer. There is slag to chip between passes, and the coating means you stop, clean, and restart more often. Arc starts are also a steeper learning curve: the rod wants to freeze to the plate until your hands learn the short, confident strike. If you are weighing stick against wire feed for a shop project, our Advantages of Stick Welding: Why SMAW Still Wins piece breaks the trade-offs down in detail.

Why OSHA treats SMAW as the reference process

Regulators treat stick welding as the benchmark hot-work process for ventilation decisions. OSHA’s welding, cutting, and brazing standards for general industry (29 CFR 1910 Subpart Q) and construction (29 CFR 1926 Subpart J) use SMAW as the reference point when sizing exhaust and respirator requirements. That alone tells you how central the process remains, and we will come back to those numbers in the safety section.

Who this guide is for

This article is written for beginners striking their first arc, farm-shop welders keeping equipment running, students working through certification practice, and DIYers tackling garage projects on mild steel. No prior code knowledge is assumed; every term gets defined as it appears.

Carbon Steel 101: What You Are Actually Welding Under the Arc

Before you worry about rods, amps, or arc starts, it helps to know what is actually sitting on your workbench. “Carbon steel” sounds like one material, but the steel you meet in a farm shop, a structural yard, or a scrap pile comes in a surprising range of grades, surfaces, and carbon contents. That range is exactly why one rod works beautifully on a trailer bracket and fails on a spring hanger.

Mild Steel Is Not “Just Iron”

Plain carbon steel is mostly iron with deliberately added carbon and manganese. Carbon gives strength; manganese does double duty as a strengthener and a deoxidizer, which is why manganese turns up later in welding fume discussions. Mild (low-carbon) steel generally sits below about 0.30% carbon, and that small number is the whole story of weldability: below that threshold, the weld and the surrounding metal cool without forming brittle, crack-prone structures. Push carbon higher, and hardenability climbs with it.

The grades you will actually encounter:

• ASTM A36 plate — the general-purpose structural workhorse. It has a specified minimum yield strength of 36 ksi (about 250 MPa) and typical tensile strength of 58–80 ksi, which is precisely why 60 ksi and 70 ksi stick electrodes are considered properly matched to it.
• ASTM A500 structural tube — square and rectangular hollow sections used in frames and trailers; thin walls that punish excessive heat.
• 1018 and 1045 bar stock — 1018 is easy to weld; 1045 medium-carbon machinable shafting behaves less kindly and benefits from preheat.
• High-carbon and spring steel — hardenable, crack-sensitive, and the reason a repair sometimes needs preheat rather than optimism.
• Cast steel and castings — often thicker, with uncertain carbon content and residual stress from casting.
• Mill-scaled, oiled, or galvanized surfaces — not grades at all, but conditions that change how the arc behaves and what comes off the surface.

When the base metal climbs into higher-carbon or alloy territory, electrode choice becomes a metallurgy question rather than a preference, which is where Alloy Steel Welding Electrodes: Selection, Use & Safety picks up the discussion.

Carbon Equivalent: The One Formula Fabricators Trust

Because manganese, chromium, molybdenum, nickel, copper, and vanadium all add hardenability too, engineers collapse the recipe into a single number called carbon equivalent, using the IIW formula:

You do not need to calculate it for a weekend repair, but understanding it explains shop rules. AWS D1.1, the Structural Welding Code — Steel, organizes steels into preheat categories, and ASTM A36 appears in both Category A (SMAW with other-than-low-hydrogen electrodes) and Category B (low-hydrogen processes). Those categories exist because the code writers already did the hardenability math for you.

Why Carbon Steel Rusts, and Why Mill Scale and Oil Matter

Unlike stainless steel, carbon steel has no chromium reserve to rebuild a protective oxide layer, so iron, oxygen, and moisture produce rust continuously. Hot-rolled plate also arrives under mill scale, that blue-black oxide layer from the rolling mill. It can break loose under the arc, interfere with grounding, and cause lack of fusion if you weld straight over it. Cutting oils, paint, and grease burn into the puddle and produce porosity. Galvanized zinc boils at a much lower temperature than steel melts, producing irritating fumes and a contaminated bead.

This is why “prep” is not fussiness: a grinder, a wire brush, a flap disc, and a solvent wipe convert a dirty repair into a weldable joint.

The Heat-Affected Zone and Cooling Rate

The arc does not only melt metal. The area just beside the weld — the heat-affected zone (HAZ) — is heated above its critical temperature and then cooled. Cooling rate depends on heat input, plate thickness, ambient temperature, and whether the part is clamped to a cold table. Faster cooling, higher carbon, and higher CE combine to form hard microstructures in the HAZ. Hardness is not a defect by itself, but hard HAZ plus hydrogen plus restraint is how cold cracks appear later, sometimes overnight.

Know the plate, check the surface, and glance at the CE when the steel is unfamiliar. Every decision in the rest of this stick welding carbon steel guide — rod, amperage, preheat, cleaning — traces back to what the base metal is doing under the arc.

How the SMAW Process Works When the Flux Coating Burns

Strip away the romance and shielded metal arc welding is a short, controlled electrical fire that you drag along a joint while a coating on the rod burns faster than the metal underneath it. Understanding what is actually happening turns stick welding from a guessing game into a repeatable skill. The good news: the physics is not complicated.

The Circuit: Where the Current Really Flows

Every stick welder is essentially a power supply — an old-school transformer or a modern inverter — that takes wall current and converts it into low-voltage, high-amperage electricity. The circuit is simple: the machine’s positive or negative lead runs to the electrode holder, through the rod, across the arc, into the workpiece, back through the work clamp and cable, and home to the machine. Break any link and the arc dies.

This is why a rusty, painted, or poorly positioned work clamp causes so much trouble. The current has to have an uninterrupted path, so a clean clamp contact point matters as much as a clean joint. Arc voltage is typically in the 20–40 volt range while amperage does the real work of melting metal. Keep the arc length roughly equal to the rod diameter: stretch it and voltage climbs, heat spreads out, and penetration drops; jam it into the plate and you short the rod straight to the work.

Starting the Arc: Scratch and Tap

There are two classic ways to get an arc going. A scratch start is exactly what it sounds like — drag the rod across the plate like striking a match, then lift to the correct length. A tap start is a quick touch-and-lift. Scratch starts are more forgiving for beginners because they build a little habit of pulling away at the right moment. Once established, the arc is a column of ionized gas conducting current between two very hot endpoints.

What the Flux Covering Actually Does

The coating is not decoration. As the arc heats it, the covering performs five jobs at once:

• Gas shield. The flux breaks down into a cloud of carbon dioxide, carbon monoxide, and water vapor that pushes atmospheric oxygen and nitrogen away from the molten pool.
• Slag blanket. Molten flux floats on the pool and solidifies on top, slowing cooling and shielding the hot metal from oxidation.
• Deoxidizers. Elements such as manganese, silicon, and titanium scavenge oxygen that would otherwise become porosity.
• Alloy transfer. The coating can add or recover alloying elements so the deposited weld metal meets its specified chemistry.
• Arc stabilization. Sodium and potassium compounds ionize easily, keeping the arc conductive and steady instead of wandering.

Three Coating Families, Three Arc Personalities

Coating family	Typical rods	Arc behavior	Notes
Cellulosic (high cellulose, sodium)	E6010, E6011	Forceful, digging arc; deep penetration	Thin, friable slag that peels easily; more smoke and moisture sensitivity; E6010 is DCEP only, the classic root-pass rod
Rutile (titanium dioxide)	E6013, E7014	Soft, quiet, easy to start	Shallow-to-medium penetration, smooth bead, very forgiving on thin and dirty sheet
Basic / low-hydrogen (calcium carbonate, fluorspar, iron powder)	E7018	Quiet, stable, high-deposition	Medium penetration with a heavier basic slag; AC or DCEP; requires careful storage

That last column hints at the AWS A5.1 numbering system, where the final digit tells you the covering type and compatible current — we will decode the full code properly in the next section.

Polarity: DCEP, DCEN, and AC

Polarity decides where heat concentrates. With DCEP (direct current electrode positive, formerly reverse polarity), roughly two-thirds of the heat lands on the plate, giving deeper penetration — this is the normal setting for E6010 and E7018. With DCEN (electrode negative), heat concentrates in the rod, so it melts off faster with shallower penetration, useful for fast fill or thin material with certain rutile rods. AC alternates direction many times per second, which cancels magnetic arc blow and lets one machine run almost any rod.

As Lincoln Electric’s AWS classification reference notes, DC-rated electrodes produce a smoother arc, while AC-rated electrodes are more forgiving on older machines. If your welder only puts out AC, you are limited to rods like E6011, E6013, and E7018 that are specifically listed for it.

What Happens on the Plate

At the leading edge of the arc, base metal melts into a small, fluid pool. The rod adds filler into that pool, and as the arc moves on, the metal solidifies from the bottom up. The slag cools more slowly on top, and once the bead is cold you chip it with a hammer and knock the surface clean with a wire brush. Skipping that step is how slag gets trapped under the next pass.

Decoding the Electrode Code: Reading AWS A5.1 Like a Pro

Pick up any stick electrode and you will find a code stamped or printed along the covering: E7018, E6011, E7018-H4R. That string of characters is not decoration. It is a compressed specification written under AWS A5.1, the specification for carbon steel electrodes for shielded metal arc welding, and once you can read it you can walk into any welding supply house and pick exactly the rod your job needs instead of guessing or relying on the counter guy’s memory. Welding by habit becomes welding by knowledge.

E7018, One Character at a Time

Take the most common structural rod in the world, E7018, and break it apart:

• E means electrode, arc welding. The rod carries the current and fills the joint.
• 70 is the minimum tensile strength of the deposited weld metal in thousands of pounds per square inch: 70,000 psi. The 60 in E6013 means 60,000 psi. Under AWS A5.1 an E7018 deposit also meets a minimum 58 ksi yield and about 22% elongation, so you are buying measurable ductility along with strength.
• 1 is the position rating. A 1 means the rod runs in all positions: flat, horizontal, vertical, and overhead. A 2 means flat and horizontal only.
• 8 identifies the flux covering family: in this case a low-hydrogen basic covering, usually blended with iron powder for smoother arcs and higher deposition.

That last digit is shorthand for the flux chemistry. The x0 and x1 groups are cellulosic, x2 and x3 are rutile, x4 adds iron powder to a rutile base, and the x5, x6 and x8 groups are low-hydrogen basic formulations. Small changes in that digit change how the rod behaves at the arc, how deep it digs, and how much hydrogen it puts into the puddle.

Reading the Suffixes: -1, H4, H8, H16, R, M

The optional characters after the digits are where code work gets serious.

• H4, H8, H16 are diffusible hydrogen designators. They set the maximum millilitres of hydrogen per 100 grams of deposited weld metal: H4 means 4 mL, H8 means 8 mL, H16 means 16 mL, all measured by the standard glycerin extraction test.
• R stands for moisture resistant. It applies only to the E7016, E7018 and E7024 types and requires no more than 0.3% moisture after exposure to 80°F and 80% relative humidity for at least nine hours.
• -1 is a supplementary requirement for improved notch toughness, meaning the deposited weld metal has been impact tested at reduced temperatures and met a specified minimum energy value.
• M indicates a military-tested electrode produced to US Department of Defense supplementary requirements, common on government and naval work.

The Common Carbon Steel Electrode Lineup

These eleven electrodes cover almost everything a repair welder, student, or fabricator meets on mild steel. Memorize the patterns rather than every row, and the rest follows.

Electrode	Covering	Positions	Current	Penetration
E6010	Cellulosic	All	DCEN	Deep, digging
E6011	Cellulosic	All	AC or DCEN	Deep, digging
E6012	Rutile	All (flat/horizontal best)	AC, DCEN or DCEP	Moderate
E6013	Soft rutile	All (flat, horizontal, overhead)	AC, DCEN or DCEP	Light to moderate
E7014	Rutile plus iron powder	All (flat, horizontal best)	AC or DCEP	Moderate
E7015	Basic low-hydrogen	All	DCEP	Medium-deep
E7016	Basic low-hydrogen	All	AC or DCEP	Medium-deep
E7018	Basic low-hydrogen plus iron powder	All	AC or DCEP	Medium-deep
E7024	High iron powder rutile	Flat, horizontal	AC or DCEP	Moderate
E7028	Low-hydrogen iron powder	Flat, horizontal fillets	DCEP	Medium-deep
E7048	Low-hydrogen iron powder	All (vertical down)	AC or DCEP	Medium

Notice what the code already told you before you struck an arc: the 60xx rods are 60,000 psi cellulosic or rutile rods for general repair, while every 70xx low-hydrogen rod clears 70,000 psi. The difference is not marketing either. E6013-class rutile deposits must meet a minimum elongation of about 17%, while E7018-class low-hydrogen deposits require roughly 22%. That extra ductility is a real metallurgical gap, and it is why structural drawings almost always specify 7018 rather than a soft rutile rod, no matter how much friendlier the 6013 is to run.

Once your project moves beyond plain mild steel into chromium-moly and other alloy steels, the same decoding logic applies to a much longer designation, which our guide to alloy steel welding electrodes walks through in detail. And if you are still building confidence running rods overhead and vertical, our all position welding rod guide covers how each electrode in the table behaves when gravity is working against you.

E6010 vs E6011 vs E6013 vs E7018: Choosing the Right Rod for the Job

Most stick welding frustration is a rod selection problem wearing a talent costume. The same welder who cannot keep an arc alive on 1/8 in plate with a 6013 will run a clean bead with a 7018 five minutes later, and the only thing that changed was the box. Four electrodes cover about 90 percent of what a farm shop, hobby garage, or student welder ever meets: E6010, E6011, E6013, and E7018. Learn what each one is built for and the choice stops being guesswork.

The Four Rods in Plain Language

• E6010 is a DC-only cellulosic rod with a forceful, digging arc that punches through mill scale and backside bevels. It is the classic root-pass and out-of-position rod on pipe and open-root joints. Deep penetration is the point, and deep penetration on thin metal is also the risk.
• E6011 is the same cellulosic family with potassium added to stabilize the arc on alternating current. That matters if your machine only puts out AC, the way older transformer and household-tap machines do. It handles rusty, painted, and generally unpleasant repair surfaces better than any other all-position rod, which is why it lives in the truck of anyone doing farm and roadside work. The AWS classification system behind these numbers is explained by Lincoln Electric’s AWS classification reference.
• E6013 is a rutile rod: soft arc, minimal spatter, moderate penetration, and slag that peels off without a fight. It is the friendly rod for clean, new sheet and light tubing, and the one most people should learn on.
• E7018 is the low-hydrogen, iron-powder rod used when toughness, appearance, and code compliance matter. It runs quiet and smooth, lays a wide flat bead, and demands clean, dry handling in return.

Two supporting players round out the box: E7014 for high-deposition fill and cap work on clean steel where penetration can be moderate, and E7024 for fast, heavy deposition in flat and horizontal production work. For higher-carbon or alloy steels, the selection logic shifts again toward preheat and matching filler, which we cover in our alloy steel welding electrodes guide.

Rod	Coating	Polarity	Penetration	Best suited to	1/8 in starting amps
E6010	Cellulosic	DCEP	Deep, narrow	Root passes, pipe, vertical-down	70–130 A
E6011	Cellulosic (potassium)	AC / DCEP	Deep, narrow	Rusty repair, farm equipment, AC-only machines	60–120 A
E6013	Rutile	AC / DC	Moderate	Clean sheet, light tubing, beginners	80–130 A
E7018	Basic low-hydrogen	DCEP (some AC grades)	Moderate to deep	Structural frames, code work, covers	110–165 A

These are published starting points only. Every manufacturer prints its own range on the data sheet, and rod diameter, wall thickness, and position all move the number, so verify against the box before you strike an arc. A quick routing rule: thin clean sheet goes to a 6013 at the low end of its range or down to 3/32 in; dirty repair with no DC goes to 6011 on AC; farm work with DC available goes to 6010; structural frames that need toughness go to 7018. A pipe or open-root pass wants a 6010 or 6011 at the low-to-mid range, position dependent. Overhead fill on clean steel runs 7018 or 7014 low and works up, and flat high-speed production fill is 7024 territory, with amperage straight off the manufacturer’s data sheet.

All-Position Work: Vertical-Up vs Vertical-Down

E6010, E6011, E6013, and E7018 are all all-position electrodes, but “all-position” does not mean “same settings everywhere.” Overhead always wants less amperage and a shorter arc, because gravity is pulling the pool out of the joint. Vertical can be run two ways, and the rod decides which makes sense. Cellulosic rods like the 6010 and 6011 are happy running vertical-down: fast travel, shallow penetration, and excellent control on thin wall tubing or an open root where you are managing a gap. Low-hydrogen rods want vertical-up, where slower travel and a slight weave let the pool build into the bevel and give structural welds the profile and toughness the joint needs. Our all position welding rod guide walks through the angle and travel-speed differences in more detail.

The Two-Rod Repair System

Experienced repair welders rarely pick just one rod. They run a pair: a 6010 or 6011 for the root, the hot pass, and anything out of position where they need to dig and move fast, then switch to 7018 for fill and cover passes where strength, appearance, and low hydrogen count. You get the penetration of a cellulosic rod and the quality of a basic rod in the same joint. The rule that makes the pairing work is cleaning: chip and wire-brush every trace of 6010 or 6011 slag before a 7018 bead goes over it, because trapped cellulosic slag becomes a slag inclusion the inspector will find later. That same habit of keeping the workpiece honest is why portability and dirty-metal tolerance remain the standout advantages of stick welding in repair work.

Machine Setup, Amperage, Polarity, and Arc Technique

Once you have a rod in the holder, everything else comes down to four variables: the machine, the polarity, the amperage, and the way you move your hand. Get those right and the bead pretty much forms itself. Get them wrong and no amount of practice will save it.

Choosing the Machine

Stick welders come in two flavors. Transformer machines are the heavy, simple AC (or AC/DC) boxes found in half the farm shops in the country. They are cheap, nearly indestructible, and repairable. Inverter machines are lighter, run on DC output, strike arcs more easily, hold a stable current at low amperage, and often include features like arc-force and hot-start that help a beginner. For carbon steel work, either will do the job; an inverter simply makes the learning curve shorter.

Check three specs on the nameplate:

• Output type: AC only, AC/DC, or DC only. DC is preferred because it gives a smoother arc and lets you choose polarity.
• Duty cycle: the percentage of a 10-minute period you can weld at rated current. A 20% duty cycle at 130 A means roughly two minutes of welding, then eight minutes of cooling.
• Amperage range: make sure it reaches down to about 40–60 A for thin sheet and up to 160 A+ for 3/16 in plate and 5/32 in rods.

Polarity: Set It Before You Strike the Arc

Each electrode family has a correct polarity, and getting it backwards is a classic reason a rod that “worked last time” suddenly sticks and sputters.

• DCEP (electrode positive): the deeper, hotter connection. Standard for E7018, E7014, E6012 and most low-hydrogen rods.
• DCEN (electrode negative): faster deposition, shallower penetration. Used by E6010 and E7024.
• AC: the compromise. E6011 is built for it, and AC also rescues you from severe arc blow when DC wants to wander.

Lincoln Electric’s AWS classification reference lists polarity and position for every common carbon steel electrode, and the manufacturer’s box is always the final authority.

Setting Amperage: The Starting Rule

The old shop rule works well on carbon steel: use roughly one amp per thousandth of an inch of rod diameter. A 1/8 in rod (0.125 in) therefore starts near 125 A. From there, tune by ear and by bead shape.

Rod diameter	E6010 / E6011	E6013	E7014	E7018
1/16 in (0.0625)	30–50 A	30–55 A	40–60 A	40–65 A
5/32 in (0.156)	80–120 A	80–130 A	110–160 A	110–165 A
1/8 in (0.125)	75–125 A (≈100 A typical)	70–130 A (≈105 A typical)	100–150 A	110–165 A (≈138 A typical)
3/16 in (0.1875)	110–160 A	120–170 A	140–200 A	140–220 A

Published typical values for a 1/8 in rod sit around 100 A for E6010, 105 A for E6013, and 138 A for E7018. Drop the current about 10–15% for vertical and overhead work so gravity does not drag the pool down, and raise it for flat fill passes on thick plate where you want speed and fusion.

Reading the Arc Instead of the Dial

Too cold: the rod sticks on starts, the bead stands up tall and narrow instead of wetting into the edges, and slag refuses to lift. Too hot: heavy spatter, undercut along the toes, a loud harsh roar, and the flux coating glowing red near the end of the rod. Just right: a steady bacon-crackle hiss, a fluid puddle with a bright outline, and a finished bead roughly two to three times the electrode diameter wide.

Angles, Travel Speed, and Drag vs Push

Work angle and travel angle decide fusion. For a flat fillet, hold the electrode at 45° into the joint, tilted 10–20° back from vertical. In the horizontal position, aim slightly upward against gravity. Vertical-up starts at the bottom of the joint and climbs, with a slightly shorter arc and slower travel. Overhead uses the tightest arc of all and the least current.

Drag (pull) — electrode trailing the direction of travel — is correct for stick welding in nearly every case, especially cellulosic and low-hydrogen rods, because the slag stays behind the arc instead of running ahead of it. Pushing is a MIG habit that causes slag entrapment on stick beads. For position-by-position detail, see our All Position Welding Rod Guide.

Joint Prep, Fit-Up, and Multi-Pass Welding on Carbon Steel

The arc gets all the glory, but fit-up decides what happens to the weld after it cools. Shop veterans put preparation at roughly 80% of weld quality, and it is hard to argue once you have seen a perfect-looking bead on a badly gapped joint crack a week later. Stick welding carbon steel is forgiving about technique and unforgiving about fit-up, and everything below happens before you strike an arc or between passes.

Cutting, Beveling, and Setting the Root

Joint geometry controls penetration and how much metal you actually have to deposit:

• Square butt. No bevel, edges left straight. Fine up to about 1/8 in (3 mm) with good penetration, and the default for sheet and light tubing.
• Single-V groove. A 30° bevel per side (60° included) for plate too thick to fuse through with a square butt. Use it up to roughly 3/4 in before the V becomes wastefully wide.
• Double-V groove. Beveled on both faces for thick plate. It halves the weld volume, balances shrinkage from both sides, and cuts distortion compared with grinding all that metal out of a single V.

Two numbers make or break the joint. The root face (the small un-beveled land at the bottom of the bevel, typically 1/16–1/8 in) gives the root pass something to melt without blowing apart. The root gap, usually 1/16–1/8 in and always per the procedure, lets the arc reach the back side of the joint. Tack welds hold both, placed short and balanced around the joint so shrinkage pulls evenly rather than pulling the gap closed on one end.

Cleaning: What AWS D1.1 and OSHA Actually Require

Mill scale, cutting oil, paint, and rust belong on the grinding side of the job, not in the puddle. OSHA 1926.353(c) lists zinc-, lead-, cadmium-, and chromium-bearing coatings as materials requiring ventilation or respiratory protection in enclosed spaces, which is exactly the situation created by welding painted or galvanized carbon steel in a shop bay. AWS D1.1 goes further, requiring removal of paint, coatings, and contaminants that could affect weld quality or introduce harmful fumes.

1. Strip paint and coatings back several inches from the joint with a grinder, flap disc, or scraper.
2. Wipe away solvent residue, grease, and cutting fluid with a clean, lint-free cloth and an approved cleaner.
3. Attack mill scale and rust with a wire cup or wire brush until you reach bright metal in the fusion zone.
4. Grind galvanized coating off the groove faces entirely, and dry out any damp plate or damp rods before you begin.

Multi-Pass Welding: Stringers, Layers, and Cleaning Between Passes

Thick carbon steel is rarely one weld. It is a stack of them. Use stringer beads (straight passes, no side-to-side motion) as the default because they put heat in a narrow, predictable band. Reserve a modest weave for capping a wide face or tying into both walls of a groove, and keep it to about two to three rod diameters. Any wider and the leading edge of the puddle outruns its shielding.

Between every pass, chip the slag completely and wire-brush the surface, then check the toes of the previous bead for undercut or trapped slag. Trapped slag is one of the most common reasons a weld fails visual or radiographic inspection, and it almost always traces back to a corner that never got cleaned. Keep the interpass temperature inside the procedure limits, commonly around 400 °F (204 °C) for ordinary carbon steel, by skipping around the joint and letting earlier beads cool rather than running them back to back.

That skip-around habit matters more than it sounds. Greater joint thickness increases cooling rate, and faster cooling drives heat-affected zone hardness up, which is exactly why D1.1 preheat requirements step up as plate gets thicker. For the broader picture, our all position welding rod guide covers how rod choice and bead sequencing work together out of position.

Open-Root vs. Bridged-Root, and Which Rod Starts It

An open root has a real gap and no backing bar, so the root pass must cut through and fuse both edges from the inside. This is where E6010 and E6011 earn their reputation: their forceful digging arc punches through the gap, bridges the land, and leaves a clean, fully fused root even when fit-up is imperfect. Pipe roots are the classic example. A bridged root, small gap with a backing strip or a tacked-in backing ring, can be filled with E7018 instead, giving you a low-hydrogen deposit from the first pass but demanding tighter gap control and a slower arc. On structural and pressure work, the root pass is chosen first and the fill and cap rods follow it.

Where a fit-up or a bead goes wrong, cutting it out and rewelding beats capping over it. For heavy sections, air arc welding and carbon arc gouging is the fastest way to remove a bad root or open a defective pass back to sound metal.

Short Note: Preheat skips are acceptable for thin, ordinary mild steel repair in a shop. They are not acceptable on thick A36, higher-carbon steels, highly restrained joints, or cold-weather work, and the same thickness increase that raises cooling rate and HAZ hardness is why the preheat table grows as the plate gets heavier.

Hydrogen Control, Preheat, and Doing Code Work to AWS D1.1

The most dangerous failure in stick welding carbon steel is rarely the one you watch happen. It is the crack that opens hours after the bead has cooled, hidden under a cover pass, in a joint that looked perfect at quitting time. Welders call it hydrogen-induced cracking, hydrogen-induced cold cracking, or HICC, and understanding it is the difference between a repair that lasts and one that fails in service.

Three Ingredients, One Crack

Cold cracking needs three things at the same moment. Remove any one and the crack cannot form.

• A hardenable microstructure. Fast cooling in the heat-affected zone transforms the steel near the weld into hard, brittle martensite. Higher carbon and alloy content makes this easier, which is why hardenability rises as you move away from plain mild steel.
• Hydrogen. Atomic hydrogen comes from moisture in the flux coating, rust, oil, grease, paint, damp backing, even humidity in the shop air. It dissolves into the molten pool, then migrates as the metal cools.
• Restraint. A thick, stiff, heavily clamped joint holds the shrinking weld in tension instead of letting it move.

The CWB Group lists the same three practical controls: use a low-hydrogen consumable or process, preheat to slow the cooling rate, and control hydrogen sources such as rust, moisture, and grease. Everything in this section is one of those three levers.

Keeping E7018 Dry: Rod Ovens, Holding Ovens, and Holding Times

Low-hydrogen only means something if the electrode stays low-hydrogen after you open the box. E7018 rods should be redried at 650–750°F (340–400°C) for about one hour if they have absorbed moisture, and opened low-hydrogen electrodes should be kept in a holding oven at 250–300°F (120–150°C).

Exposure time matters more than most beginners realize. Lincoln Electric’s guidance is straightforward: opened cans of standard EXX18 electrodes should be supplied to welders twice per shift, while moisture-resistant (R) types may be exposed longer before they need to go back to the oven.

The reason ovens must be separated is chemistry. Cellulosic E6010 and E6011 coatings hold roughly 4–6% moisture as manufactured, while low-hydrogen basic coatings hold about 0.1–0.4%. Store a batch of 6010 beside your 7018 in one holding oven and the 7018 rods will pick up what the cellulosic rods are releasing, quietly destroying the low-hydrogen performance you paid for. Cellulosic rods never go in a holding oven at all.

Preheat and Interpass Temperature Under AWS D1.1

AWS D1.1, Structural Welding Code — Steel, sets preheat and interpass temperature in Table 5.11 (formerly Table 3.2) and offers alternative calculations and diagrams in Annex B. The table is organized around two categories that catch people off guard:

Category	Coverage	Practical effect
Category A	Listed steels including ASTM A36 welded with other-than-low-hydrogen SMAW electrodes	More preheat required at a given thickness
Category B	The same steels welded with low-hydrogen processes	Less preheat, and often none at common thicknesses

In other words, rod choice literally changes the preheat column you sit in. Swapping a 6011 repair for a 7018 low-hydrogen process can remove the preheat requirement entirely on ordinary A36 plate. The carbon equivalent formula (CE IIW) does the same job on the metallurgy side: the more carbon and alloy you have, the more hardenable the joint, and the more hydrogen it can tolerate before cracking. If you are moving into alloyed material, our Alloy Steel Welding Electrodes: Selection, Use & Safety guide covers how electrode chemistry is matched to those hardenable base metals.

When Preheat Can Be Skipped, and When It Absolutely Cannot

For a bracket, a farm implement, or a noncritical mild steel repair on thin A36 in a warm shop, preheat is usually unnecessary with a low-hydrogen rod. Skip it comfortably there. Do not skip it when you are dealing with:

• thick A36 sections where restraint is high,
• higher-carbon or alloy steels with elevated carbon equivalent,
• fully restrained joints such as boxed or closed corners and heavy pipe,
• cold weather, where the base metal acts as a heat sink and accelerates cooling.

Preheat slows cooling so hydrogen can diffuse out instead of being trapped, and it does the same job as a post-weld hold. Interpass temperature simply means keeping that same floor temperature between passes rather than letting the joint fall back to ambient.

Treat hydrogen control as a habit rather than an emergency response: sealed rod packaging with lot traceability, a clean and dry joint, an oven that actually holds temperature, and a preheat decision made before the arc starts. Cracks are cheap to prevent and expensive to find.

Troubleshooting: Common Stick Welding Defects on Carbon Steel and How to Fix Them

Almost every ugly bead on carbon steel traces back to a short list of causes: too much heat, too little heat, a dirty joint, a damp rod, or a rushed stop. The good news is that stick welding shows its problems plainly. Learn to read a defect and you can usually name the mistake before the metal cools. Start with this diagnostic chart, then work through the details below.

Quick Defect Diagnostic Chart

Defect	Usual causes	First fix
Porosity	Moisture in the rod, oil/paint/mill scale, wind	Clean the joint, use dry rods, block drafts
Undercut	Amperage too high, arc too long, wrong travel angle	Drop amps, shorten arc, slow down
Slag inclusion	Skip cleaning between passes, undercut left behind	Chip and brush every pass, grind the previous toe
Lack of fusion / cold lap	Setting too cold, poor fit-up, wrong electrode	Raise amps, fix fit-up, switch rods
Excessive spatter	Long arc, damp rods, AC on a DC-only rod	Check polarity, dry storage, shorter arc
Arc blow	Magnetic disturbance on DC runs	Switch to AC, add run-on tab, anchor the end
Rod sticking	Cold setting, hesitant arc start	Bump amps slightly, use a confident scratch start
Burn-through	Too much heat on thin sheet	Lower amps, stitch and tack, keep moving
Crater cracks	Stopping abruptly at the crater	Back up and fill, use a run-off tab
Under-bead cracking	Hydrogen + hard microstructure + restraint	Cut out and reweld, never cap over

Porosity and Undercut

Porosity is a cleanliness and storage problem more than a technique problem. Water in the flux, cutting oil, paint, rust, or a breeze blowing across an open root all inject gas into the puddle. Low-hydrogen rods are especially sensitive: Lincoln Electric documents a clear severity ladder as electrode moisture rises. First you get internal porosity visible only by x-ray or destructive testing, then visible surface porosity with a rough bead and stubborn slag, and finally cracking, including under-bead cracking. That ladder is exactly why rod ovens and sealed cans matter more than they look.

Undercut is a bead-toe groove cut by the arc and left unfilled. The classic drivers are excessive current, excessive arc length, and improper travel angle, especially tilting too far forward at speed. Drop the amperage a little, keep the arc tight, and slow down so the puddle washes into the toe.

Slag Inclusions and Lack of Fusion

Slag inclusion is largely a technique and interpass-cleaning defect, and it remains one of the most common reasons structural welds fail visual and NDT inspection. Chip, wire-brush, and grind the previous pass before the next one goes on, and watch for undercut along the last toe, where slag hides best. Wide weaves over cold passes make it worse; smaller stringer beads layered cleanly solve it.

Lack of fusion, or cold lap, means the new bead never bonded to the wall or previous pass. It comes from a setting that is too cold, a gap too wide or too tight, or a rod that cannot dig far enough for the joint. If you are running out-of-position, the all-position welding rod guide covers which coatings hold a puddle overhead and vertical.

Spatter, Arc Blow, Stopping Clean

Excessive spatter usually means a long arc, damp rods, or AC running a rod designed for DC. Arc blow is magnetic wander that pushes the puddle sideways on DC runs; fix it with AC output, a run-on tab, or by anchoring the last two inches of a joint with a small tack. Rod sticking is nearly always a cold setting combined with a tentative arc start. On thin material, burn-through means back off the amperage and stitch. Crater cracks come from lifting off abruptly: back up over the crater and fill it, or finish on a run-off tab you cut off later.

Cracking: The One You Never Weld Over

Hydrogen-induced cracking needs three ingredients together: a hardenable microstructure, hydrogen, and restraint. Under-bead or hairline cracking in higher-strength steels is a hydrogen signature, and the correct response is removal of the affected weld and rewelding with controlled low-hydrogen practice. Cutting it out feels drastic, but grinding a cap over a crack simply hides it until load is applied.

Fix defects at the source. A repair that repeats the same cause will crack or undercut again on the next pass.

Safety: Fumes, Ventilation, PPE, and Staying Healthy for a Whole Career

The final skill in this guide has nothing to do with rod angle or amperage. Stick welding carbon steel produces fume, UV, spatter, and noise every hour you strike an arc, and the welders who last thirty years in the trade are the ones who treated ventilation and PPE as part of the technique, not as an annoyance. Here is the health reality, the OSHA numbers in plain language, and a practical order of operations for protecting yourself.

What Is Actually in Stick Welding Fume

When the flux coating burns it generates a shield of gas and slag, and a portion of that plume rises past your helmet as weld fume. On plain mild steel the particulate is mostly iron oxides plus a smaller but important amount of manganese oxide from the steel and the covering. The gaseous by-products include carbon monoxide, carbon dioxide, and nitrogen oxides formed as the hot arc splits and recombines atmospheric nitrogen and oxygen. Burning off oil, paint, primer, or galvanizing adds whatever was on the plate to that list, which is one more reason cleaning comes before welding.

Two health outcomes matter most:

• Metal fume fever is a flu-like illness with delayed onset: chills, fever, nausea, and body aches that show up a few hours after exposure, often clearing within a day. OSHA’s assessment of the PEL rulemaking, citing field research, estimated that 30–40% of welders have experienced it. Zinc from galvanized steel is the classic trigger, but fume from mild steel can cause it too (OSHA welding safety factsheet).
• Manganese exposure is the long-concern issue, linked to neurological effects with heavy chronic exposure. NIOSH recommends a 1 mg/m³ TWA and 3 mg/m³ STEL for manganese, while ACGIH’s TLV for the respirable fraction sits far lower at 0.02 mg/m³ (NIOSH manganese topic page). In a NIOSH field study of refinery construction stick welders, full-shift total-particulate manganese geometric means were 99 µg/m³ inside confined spaces versus 8.7 µg/m³ outside, and 18 welder samples exceeded the ACGIH TLV for total manganese (NIOSH welding program).

OSHA’s own exposure limit for welding fume is 5 mg/m³ of total particulate as an 8-hour average. And a quick word on materials outside the mild-steel lane: welding stainless or certain coated and alloy steels introduces hexavalent chromium, which carries its own strict PEL and medical-surveillance requirements. That is a genuine reason to know exactly what alloy you are welding before you burn it (Alloy Steel Welding Electrodes: Selection, Use & Safety).

Ventilation Rules in Practical Numbers

The governing rule for general industry is 29 CFR 1910.252(c), with the construction counterpart at 29 CFR 1926.353. In plain terms:

• Where welders work in a space of less than 10,000 cubic feet per welder, where the ceiling is lower than 16 feet, or where cross ventilation is obstructed, you need mechanical ventilation of at least 2,000 cfm per welder.
• Local exhaust hoods must be positioned to draw the plume away from your face, with minimum flow velocities and hood distances specified in OSHA’s table for low-hood and flanged-inlet hoods.
• In confined spaces, general ventilation is generally not enough on its own: OSHA requires airline respirators or an equivalent air supply when fume concentration cannot be brought below the PEL, and a permit-style atmosphere test comes first (OSHA small entity compliance guide).

The Hierarchy of Controls, Applied to the Arc

Work down this list in order and stop at the first one that solves the problem:

1. Substitution — choose the lowest-fume process or consumable that still meets the job, and strip paint, oil, and galvanizing before striking an arc.
2. Local exhaust ventilation — a fume extractor arm with the hood near the arc is the single most effective shop purchase you can make.
3. Positioning — stand upwind or to the side of the plume, never directly above it, and keep your head out of the rising column.
4. General ventilation — fans, open doors, and the 2,000 cfm rule to dilute what remains.
5. Respirators — the last line, not the first; fit-tested half-face P100 cartridges for ordinary mild-steel work, supplied air in confined spaces.

PPE: The Gear Between You and the Arc

• Lens shade: auto-darkening helmets are worth the money; for typical stick currents on carbon steel, a shade 10 to 13 covers most amperage ranges.
• Leathers: a jacket or welding shirt with cuffs closed, plus a cap or beanie to stop sparks from landing in your hair.
• Gloves: dedicated stick-welding gloves with longer cuffs; MIG gloves are too thin for 7018 spatter.
• Hearing: the arc and the chipping hammer both add up — foam plugs or earmuffs belong in every stick session.
• Fire watch: thirty minutes of watching after the last arc, especially anywhere slag can fall into insulation, sawdust, or cardboard.

None of this is glamorous, and none of it is optional. The habits cost seconds once they are routine: extractor arm swung into place, cuffs buttoned, plugs in, fire watch assigned. What they buy is the part of the trade that matters more than any single bead — the ability to still be striking arcs comfortably decades from now, with your lungs, hearing, and eyes intact. Treat ventilation and PPE as technique, and stick welding carbon steel stays a forgiving process for as long as you want it to be.

Frequently Asked Questions

What is the best stick electrode for welding mild carbon steel?

For clean new steel and beginners, E6013 is the easiest rod to run. For dirty, rusty, or out-of-position repair work, use E6011 (AC) or E6010 (DC). For anything structural or where strength and toughness matter, E7018 is the standard choice because of its low-hydrogen deposit and 70,000 psi tensile strength.

Can I stick weld carbon steel with a cheap AC-only stick welder?

Yes. AC-only machines run E6011 and E6013 perfectly well, which covers most hobby and farm repair work. You cannot run standard E6010 or E7018 on pure AC, though many AC/DC machines include AC-rated 7018 variants. If you plan to do structural work later, an AC/DC machine is worth the upgrade.

What polarity should I use for E7018 on carbon steel?

DCEP (electrode positive, also called reverse polarity) is the preferred polarity for E7018 and gives the smoothest arc and best deposit characteristics. AC-rated low-hydrogen variants exist for machines without a DC setting, but DCEN (straight polarity) is not the intended polarity for this electrode.

Do I need to preheat before welding mild steel like A36?

For thin, unrestrained mild steel repair with a low-hydrogen rod, preheat is usually unnecessary. AWS D1.1’s preheat table (Table 5.11) steps preheat up with thickness, joint restraint, steel grade, and electrode hydrogen level, so thick A36, higher-carbon steels, cold-weather work, and restrained joints often require preheat measured with a temperature stick or IR thermometer.

Why does my welding rod keep sticking to the metal?

Almost always the amperage is too low, the arc start is too slow, or the base metal is cold or dirty. Raise the current slightly toward the middle of the published range, use a quick scratch or tap start, and keep the arc length about the same as the rod diameter. On E7018, also check that the rod tip is not contaminated by a dropped end.

How should I store E7018 rods so they do not go bad?

Keep unopened low-hydrogen rods in their hermetically sealed containers. Once opened, store them in a rod oven or heated cabinet at roughly 250–300°F (120–150°C). Exposed rods can be re-dried at about 650–750°F (340–400°C) for one hour per manufacturer guidance — never at higher temperatures, which damages the coating.

Is the smoke from stick welding carbon steel dangerous?

Welding fume on carbon steel is mainly iron and manganese oxides plus gases such as carbon monoxide, and it can cause metal fume fever and, with long-term exposure, respiratory and neurological effects. Weld in ventilated areas, use local exhaust where possible, stay upwind outdoors, and wear appropriate respiratory protection when ventilation cannot keep the air clean.

How strong is a stick weld on carbon steel?

A properly made E7018 weld deposits metal with a minimum tensile strength of about 70,000 psi (480 MPa), which overmatches common A36 structural steel (36 ksi yield, 58–80 ksi tensile). An E6010 or E6013 weld deposits at least 60,000 psi, still adequate for many mild steel applications but with less margin and no low-hydrogen benefit.

Can I stick weld rusty, painted, or galvanized carbon steel?

You can burn through light rust and mill scale with a digging rod like E6011, but grinding back to bright metal always produces a better weld. Paint, galvanizing, and coatings should be removed near the joint because they can create porosity and release toxic fumes — OSHA specifically lists zinc-, lead-, cadmium-, and chromium-bearing coatings as materials needing ventilation controls.