Welding rod means three different things, and confusing them is the most common mistake a beginner makes. A stick electrode is consumable, flux-coated and carries the current. A TIG filler rod is bare, carries no current and is not an electrode at all. A tungsten electrode carries the current and never melts. Only the first has the famous four-digit number.
The three things called a welding rod
| Stick electrode | TIG filler rod | Tungsten electrode | |
|---|---|---|---|
| Carries the welding current | Yes | No | Yes |
| Melts into the weld | Yes, it is the filler | Yes, it is the filler | No, never |
| Coated | Yes, in flux | No, bare | No |
| Numbered like E6013 | Yes | No, ER-numbers such as ER70S-6 | No, EW-numbers such as EWLa-2 |
| Standard | AWS A5.1 (carbon steel) | AWS A5.18 and others | AWS A5.12 |
Reading a stick electrode number
Take E7018. Hobart Brothers, who make them, break it down like this: the E marks it as an electrode - a part of the welding circuit that conducts current and terminates at the arc. The 70 is the tensile strength of the deposited metal in thousands of pounds per square inch, so 70,000 psi. The third digit is the welding position, and a 1 means all positions. The fourth digit describes the coating.
What each part of E7018 means
| Part | Meaning |
|---|---|
| E | Electrode: it conducts the welding current |
| 70 | Tensile strength of the deposit, in thousands of psi |
| 1 | Welding position. 1 is all positions; 2 is flat and horizontal fillets only |
| 8 | The flux coating, which also fixes what current the rod will run on |
The fourth digit is the one worth understanding, because the coating decides both how the rod behaves and whether it will run on your machine at all. The full table of coating codes is in AWS A5.1; what matters in practice is the polarity each one demands, and for that the manufacturer's own data sheet is the authority rather than any chart. What AC and DC change is the other half of that answer.
The four rods that cover most work, from the makers' data sheets
| Rod | Runs on | Amperage, 1/8 inch | What it is for |
|---|---|---|---|
| E6010 (Lincoln Fleetweld 5P+) | DC electrode positive only | 75-130 A | Deepest penetration, cuts through rust and paint. Will not run on AC |
| E6011 (Hobart 335A) | AC or DC electrode positive | 80-125 A | The 6010 you can run on an AC machine |
| E6013 (Lincoln Fleetweld 37) | AC or DC, either polarity | 110-150 A | Easiest to strike and run. The learning rod |
| E7018 (Hobart 7018 XLM) | DC electrode positive or AC | 90-160 A | Low hydrogen, structural work, x-ray quality |
Two brands of the same classification can differ by twenty amps at the same diameter, which is why the brand is named beside each row. Read the box your rods came in - and setting the machine to match it is the rest of the job.
TIG filler rods are not electrodes
This is where most rod guides go wrong. In TIG the electrode is the tungsten; the filler rod is a bare wire you dip into the puddle with your other hand and it carries no current. It is numbered under a different system entirely - and how the two hands work together is the skill the numbering hides.
- ER70S-6 and ER70S-2 - mild steel. Hobart explain the code: E and R mark it as usable as an electrode or a rod, 70 is the tensile strength, S means solid wire, and the final digit is the chemical composition. An optional H suffix means it meets a diffusible hydrogen requirement
- ER308L - for 304 stainless. The L is low carbon, which matters for corrosion resistance at the weld
- ER4043 and ER5356 - aluminium. 4043 flows well and is more forgiving; 5356 is stronger and takes anodising more evenly
- ER70S-6 is also the standard MIG wire, because the same specification, AWS A5.18, covers both - the wire on a MIG spool and the rod in your left hand can be the same alloy
Tungsten electrodes: the ones that never melt
Tungsten is the non-consumable electrode in TIG. Classifications and colour codes come from AWS A5.12; the uses below are the ones CK Worldwide, who manufacture them, publish for each type.
Tungsten electrodes
| Type | AWS class | Colour | Use |
|---|---|---|---|
| 2% lanthanated | EWLa-2 | Blue | General purpose, AC and DC. The one to buy if you buy one |
| 1.5% lanthanated | EWLa-1.5 | Gold | DC. The non-radioactive substitute for thoriated |
| 2% ceriated | EWCe-2 | Grey | AC or DC, good at low-amperage starts |
| 2% thoriated | EWTh-2 | Red | DC. Contains thorium oxide and is radioactive |
| 0.8% zirconiated | EWZr-8 | White | AC, aluminium and magnesium |
| Pure | EWP | Green | AC only, non-critical work |
The red one is the one to stop buying. Thorium is radioactive, and grinding an electrode to a point - which you do constantly - makes a dust of it. Two percent lanthanated does the same job on DC, works on AC too, and is not radioactive. Note that AC is only useful if the machine has it: our comparison of TIG machines separates the AC/DC ones from the DC-only ones, because a DC machine will not weld aluminium whatever tungsten is in it.
How to store them, which is not optional for two of them
- E6010, E6011, E6013 - ordinary dry storage. Hobart say their E6011 should be kept dry at room temperature and never in an oven above 130 degrees F
- E7018 and other low hydrogen rods - a heated rod oven, or a sealed tin. If the flux looks chalky or the rod snaps rather than bends, throw it away
- Aluminium electrodes - dry, sealed, and discarded once they have been open in a damp workshop
- Tungsten - does not spoil, but keep the ground points from knocking together in a drawer
- MIG wire - a spool left on the machine rusts. Bag it with the desiccant when the job ends
Frequently asked questions
What do the numbers on a welding rod mean?
On a stick electrode such as E7018: E means electrode, 70 is the tensile strength of the deposit in thousands of psi, the third digit is the welding position - 1 for all positions - and the fourth describes the flux coating, which also fixes what current the rod will run on. TIG filler rods and tungsten electrodes use different systems entirely.
What is the difference between 6011 and 7018?
Penetration against quality. E6011 digs through rust and paint and runs on AC, which makes it the field repair rod. E7018 is low hydrogen and deposits 70,000 psi metal for structural work, but it needs clean steel, DC electrode positive or AC, and dry storage in a heated oven. They are not substitutes for each other.
Which welding rod is best for beginners?
E6013 in 1/8 inch. It strikes easily, runs on almost any machine at any polarity, and is forgiving of an unsteady hand. Its penetration is shallow, so it is not the rod for anything structural - but nothing you weld in the first month should be structural.
Can you use a TIG filler rod as a stick electrode?
No. A TIG filler rod is bare wire with no flux coating, so there is nothing to shield the arc and nothing to form slag. It would burn back and contaminate the weld. The reverse does not work either: a flux-coated stick electrode fed into a TIG puddle puts flux into the weld.
Do welding rods expire?
Flux-coated ones effectively do. Low hydrogen rods such as 7018 take up moisture from the air, and that moisture becomes hydrogen in the weld, which cracks it. Hobart publish a rebake schedule for theirs. Aluminium electrodes have the same problem with no published rebake, so they are simply discarded. Bare TIG rods and tungsten do not spoil.
Sources
- Hobart Brothers - the basics of AWS filler metal and stick electrode classification
- Lincoln Electric - Stick Electrode Welding Guide (PDF): amperage and polarity for Fleetweld 5P+ and 37
- Hobart Brothers - 335A (E6011) data sheet (PDF)
- Hobart Brothers - 7018 XLM data sheet (PDF): the oven and rebake temperatures
- CK Worldwide - tungsten electrode types and colour codes
- AWS A5.3/A5.3M:2023 - aluminium covered electrodes (preview PDF)
- Inside The Kerf - stick welding rods explained
In short
Three different things are called a welding rod, and only the stick electrode has the four-digit number. Read it as strength, position and coating, and let the coating tell you the polarity. Beyond that, most shops need four stick electrodes, two TIG filler rods and one tungsten - 6013 to learn on, 6011 for rusty field work, 7018 for anything that matters, ER70S-6 and ER308L for TIG, and 2% lanthanated tungsten because it does both AC and DC without being radioactive.