Purple Tungsten for TIG Welding: Uses, Pros & Best Settings

A fabricator swaps in a box of purple-banded electrodes after years of red thoriated tips, and the first thing he notices is not a dramatic weld transformation — it is that the arc starts the same on the first cold morning, without the radioactive-materials paperwork his shop required for thorium. That quiet swap raises the real question: what exactly is purple tungsten, and does it actually earn a place in your tungsten organizer?

What Purple Tungsten Really Is (and Why the Band Is Purple)

Short answer: a purple-banded tungsten electrode is a lanthanated tungsten electrode, alloyed with about 1.5% lanthanum oxide (La₂O₃) and sold under the AWS classification EWLa-1.5. That single band color tells a welder, a distributor and a purchasing department exactly what is inside the tube before a single arc is struck.

The governing standard is AWS A5.12/A5.12M, the specification for tungsten and oxide-dispersed tungsten electrodes used in arc welding and cutting. The “EW” prefix on every classification stands for electrode, tungsten, and everything in the color system below traces back to that document.

Why Color Bands Exist at All

Before color coding, welders identified electrode type by the shape of the point and by a stamp on the packaging, which is slow and easy to get wrong. The band solves that in about half a second of shop-floor time. It sits on the tip end of the electrode, the part that lives inside the torch, so you can check the type without breaking the box seal, pulling the electrode from the collet, or squinting at fine print under fluorescent shop lights. Band position on the body also varies by grade, but the tip band is the primary identifier, and for loose, pre-sharpened electrodes the tip color is all you see anyway.

The tungsten selection guidance from Miller makes the same practical point: the color code exists so the right electrode lands in the right torch, which is the single biggest cause of a bad arc.

Purple and Blue: The Only Difference Is the Oxide Percentage

This is where people get confused. Purple (EWLa-1.5) and blue (EWLa-2) belong to the same family of material: tungsten with lanthanum oxide dispersed through it. The only chemical difference is how much lanthanum oxide is in the mix, 1.5% for purple and 2% for blue. Both are non-radioactive, both run on AC and DC, and both are what most modern shops call general-purpose lanthanated electrodes.

Why two grades? A slightly lower oxide content tends to give a gentler, finer arc with more resistance to erosion, which some fabricators prefer for thin-gauge and precision work. The 2% version holds a little more current capacity and is generally the harder-working of the two. That same logic of picking the closest fit rather than the strongest option runs through the full practical guide to aluminum MIG welding.

What Tungsten Actually Does in GTAW

Tungsten is the non-consumable electrode in gas tungsten arc welding. It is not melted into the puddle the way a stick rod or MIG wire is. It sits in the torch, carries current, and does one job: thermionic emission, the release of electrons from the hot metal surface that create the arc. Tungsten suits that job because its melting point is about 3,422 °C (6,192 °F), the highest of any pure element, which is why it became the standard filament and electron-emitting material in light bulbs and electron microscopes too. The arc column can exceed the melting point of the electrode tip itself, and tungsten still refuses to melt away. That is why an electrode can be ground, used again and ground again for a long service life while pointing at much softer steel.

Why a Tiny Percentage of Oxide Matters

Pure tungsten (green band, WP) works, but it makes life harder. The mechanism comes down to one word: work function, the energy an electron needs to be freed from the surface of the metal. Pure tungsten has a high work function, so the tip must get extremely hot before it gives up electrons, which means a less forgiving arc, a harder start in cold weather and a tip that erodes quickly. A small amount of lanthanum oxide dispersed through the tungsten lowers the work function and makes electron emission easier and more consistent. The result is an arc that starts sooner, holds steadier, resists contamination from dirty base metal and carries more current without the tip crumbling away.

Lanthanum oxide is chosen over thorium oxide because lanthanum is not radioactive. The red-band 2% thoriated electrode (EWTh-2) works beautifully, but it introduces thorium-232 into the shop and with it regulatory obligations that many small fabricators would rather not carry. Lanthanated tungsten gives most of the same arc behavior with a fraction of the paperwork.

So, in one sentence: purple tungsten is a non-radioactive, 1.5% lanthanum oxide alloy of tungsten, sold as EWLa-1.5 and color-banded purple at the tip so you can put the right electrode in the right torch without thinking about it. The rest of this guide covers how that oxide changes the arc, how purple compares with blue, red, gray, white and green, and how to grind and set up.

Related reading: Aerospace TIG Welding: standards, techniques and training covers the high-stakes end of TIG, where electrode and gas control matter far more than they do on a weekend project.

How Alloying Oxides Change the Arc: The Science Behind the Color

Every color in a tungsten box comes from one idea. Adding a small percentage of a metal oxide to the tungsten rod changes how the arc behaves, how long the tip lasts, and how easily your machine starts. That oxide is the reason green, red, gray, blue, purple and white electrodes exist. Understanding what it does is the fastest way to understand why a fabricator picks one color over another.

Why Pure Tungsten Needed Some Help

Green tungsten is pure tungsten, and for decades it did the job. It is inert and will not contaminate the weld, which is why it still has loyal users on AC aluminum. The problem shows up at the extremes. At low amperage the arc hunts and wanders across the work. Push the current up and the tip softens, rounds over and can spit molten tungsten into the puddle. Worse, a tip that picks up copper, aluminum or steel will wander in a way no operator skill can fix.

The industry answer, refined over decades, is to disperse a few percent of a metal oxide in the tungsten. AWS classifies these doped compositions in the A5.12 specification for tungsten welding electrodes, and industry guidance such as the updated tungsten electrode guidelines from The Fabricator spells out what each oxide contributes.

The Two Jobs an Oxide Does

The first job is electrical, and it comes down to work function: the energy it takes to pull a single electron loose from the surface of a metal. A TIG arc is a stream of electrons. In DCEN the tungsten tip is negative, so electrons must be ripped off the tip and thrown at the workpiece. The harder that is, the hotter and more abused the tip must get before it can supply them. Lower the work function and the tip gives up electrons easily, even at low current and even when it is barely warm.

Think of the tip as a bucket of electrons under a stubborn lid. Pure tungsten has a heavy lid. Add an oxide and the lid becomes light, so the arc lights at a touch instead of a heave. This improved thermionic emission is why doped electrodes start so easily, especially on a cold morning or a dirty workpiece.

The second job is structural. The oxide particles pin down the tungsten’s grain structure near the tip. In pure tungsten the grains grow, the tip melts back and balls up, and it holds contamination badly. With dispersed oxide, the tip holds its shape under heat, resists melt-back and recovers better when it does get contaminated.

What Lanthanum Oxide Specifically Changes

Lanthanum oxide (La₂O₃) is dispersed through the tungsten matrix rather than sitting on the surface. A typical 1.5% lanthanated rod is roughly 99% tungsten with the balance lanthanum oxide, as described in the Washington Alloy 1.5% lanthanated data sheet. In practice, the result is an electrode that starts at low amperage, runs a tighter and more focused arc column, burns off more slowly, and handles both AC and DC. Miller’s tungsten guide notes that lanthanated electrodes carry high current without spitting and stay stable at both high and low amperage, which is exactly the wide-range behavior most shops want from a general-purpose rod.

The focused arc matters more than it sounds. A narrow column puts less heat into the surrounding puddle and more into the joint, which is why lanthanated rods are a favorite for thin material, tube work and the tight, controlled passes required in aerospace TIG welding and similar critical fabrication.

Why Inverters Changed the Rules

Electrode preference shifted because the machines changed. With 1940s transformer power sources, Miller documents that pure tungsten was the standard for AC aluminum and 2% thoriated (red) the default for nearly everything else. Those machines started softly and lacked high-frequency ignition.

Modern inverter TIG sources do the opposite. High-frequency start is effectively a tiny lightning strike at the tip, and square-wave or fast-switching current reverses thousands of times per second. That is a much harsher duty cycle for the electrode. Miller also notes that thoriated tungsten has fallen out of favor on today’s inverters, and welders moved toward lanthanated, ceriated and rare-earth electrodes that tolerate high-frequency starting and square-wave output far better. The physics did not change. The machine did.

What It Looks Like at the Bench

Talk to any shop that switched and the same three comments come up. Starts are cleaner, so the first inch of a bead no longer wanders while you chase it with the torch. Spitting drops, so there is less tungsten contamination to grind out of the bead. And grind life stretches, because the tip holds its point instead of rounding off after one job. Unlike a consumable stick electrode, the tungsten is not filling the joint, so every bit of tip degradation shows up as arc behavior instead of weld metal, which is why the comparison between SMAW and TIG consumables comes down to arc control rather than filler chemistry.

None of this is magic. It is a small percentage of oxide doing two unglamorous jobs: making electrons easier to release and keeping the tip physically intact. That is why purple lanthanated starts like a modern electrode and holds up like one.

Full Tungsten Color Chart: Purple vs Blue, Red, Gray, Green, White and More

Every drawer of TIG electrodes ever shipped has the same idea built in: grab the right color without reading anything. The bands come from the AWS A5.12 standard, which defines both the alloy chemistry and the classification code printed on the box, and manufacturers color the tip end of each rod so you can identify it at a glance, even in the dark.

Here is the reference chart welders actually keep beside the machine, expanded with the supplier-specific colors at the bottom.

Color	Type / Composition	AWS Class	Polarity	Best Materials	Arc Character	Radioactive?
Green	Pure tungsten	WP (E)	AC (DC possible)	Aluminum and magnesium, especially on older transformer machines	Soft, wide and less focused; tip usually balled rather than pointed	No
Red	2% thoriated	EWTh-2	DCEN (AC usable)	Carbon steel, stainless, nickel alloys; heavy DC work and deep penetration	Hot, penetrating, extremely stable on DC; resists erosion at high amperage	Slightly (thorium-232)
Gray	2% ceriated, typically 1.80% to 2.20% cerium oxide	EWCe-2	DCEN and AC	Thin stainless, food-grade and surgical work, low-amperage precision	Very stable short arc at low current; the favorite for thin-gauge stainless	No
Blue	2% lanthanated	EWLa-2	DCEN and AC	Everything. Stainless, carbon steel, aluminum, copper, nickel and titanium alloys	Focused, all-polarity arc with high current capacity; the general-purpose workhorse	No
Purple	1.5% lanthanated	EWLa-1.5	DCEN and AC	Everything. Same all-metal reach as blue, often preferred for fine work and tube	Slightly gentler and marginally finer than blue, with slower tip erosion	No
White	Zirconiated	EWZr-1	AC (DC possible)	Aluminum and magnesium on AC	Excellent AC cleaning and penetration balance on aluminum	No
Gold / Yellow	Rare-earth mixes, blend varies by supplier	No fixed A5.12 class	DCEN and AC	Mixed production work, auto and robotic cells	Arc character changes with the blend; good all-round starting	No
Chartreuse / Lime	Yttriated and rare-earth blends	No fixed A5.12 class	DCEN (some AC)	Automated low-current arc starts and repeat production	Very easy to start, extremely stable at low amperage	No
Brown / Orange	Yttriated, roughly 0.5% yttrium oxide	Not separately classified in A5.12	DCEN and AC	Low-current work and automated starts	Excellent arc starting, similar to a premium lanthanate	No

For the deeper chemistry behind each column, the AWS A5.12 preview document sets out the classification rules, and Miller’s tungsten selection guide is a good free reference for how each color behaves at the torch.

Purple vs Blue: How to Choose

Here is where most people get confused, because purple and blue do nearly the same job. Both are lanthanated, both run on AC and DCEN, both work on every common metal, and both are non-radioactive. The difference is the lanthanum oxide loading and the result that follows from it.

At 1.5% lanthanum, the arc is commonly described as a touch gentler with a marginally finer profile and slightly slower erosion of the tip. Welders who run thin stainless, tube work, or small precise joints often report that the arc hugs the puddle more predictably and stays cleaner at low amperage. Purple is the sensible pick for a shop that wants one non-radioactive electrode for everything, especially in aerospace-adjacent work such as thin-gauge titanium and stainless where arc control matters, as detailed in this aerospace TIG welding reference.

At 2% lanthanum, you get a bit more current-carrying capacity and a harder-hitting arc that is why blue became the general-purpose default and the electrode Miller most often recommends. Blue is the better answer when you are running thicker material, stacking up amperage, or want the maximum all-round capacity in one rod. For high-amperage DC work on heavy alloy steel, some shops still prefer red for its penetration and erosion resistance, which you can read about in this alloy steel electrode guide.

Practical rule of thumb: if you are not sure, choose blue for maximum capacity, purple for maximum finesse. Suppliers describe the difference in similar terms on their own product pages, for example this 1.5% lanthanated electrode listing.

One last practical note. Green and white exist for a reason. If your shop still runs transformer-style AC power for aluminum, pure tungsten with a balled tip and zirconiated white are the proven answers, and no amount of lanthanum will change that. For modern inverter machines that run AC electronically, purple and blue handle aluminum perfectly well, which is one more reason many shops now run a single electrode across every job on the floor.

When Purple Tungsten Performs Best: Metals, Processes and Amperage

Purple tungsten is not a specialist electrode. A 1.5% lanthanated electrode rated EWLa-1.5 under AWS A5.12 is an all-polarity, all-metal electrode, and it performs credibly on nearly everything that comes out of a TIG torch.

The 2% blue is rated the same way. Both types run AC and DC, covering mild steel, stainless, aluminum, magnesium, copper, titanium and nickel alloys, so one box of purple can replace three or four color codes on the bench.

Polarity and material pairing

Most of your time on direct current goes to DCEN (electrode negative, workpiece positive), which puts roughly two-thirds of the heat into the work, what you want for stainless, mild steel, copper, titanium and nickel alloys. Aluminum and magnesium need AC, where each half-cycle reverses so the cleaning action scours the aluminum oxide layer off the joint while the penetration half still fuses it. Lanthanum keeps a stable arc through the flip.

Magnesium is the exception to the exception: it burns so readily that most shops need the DC cleaning action or a dedicated magnesium setup, so treat it case by case.

Where lanthanum’s low-current behavior earns its keep

Purple earns its place on thin work because of the arc itself. A small percentage of lanthanum oxide lowers the tungsten’s work function, so the tip sheds electrons more readily at low amperage. The arc starts and holds where a plain tip would sputter, wander or refuse to strike.

• Thin sheet and foil in stainless, mild steel and titanium at 10 to 50 amps with a 1/16 in electrode, keeping heat input low.
• Precision work on stainless tubing and fittings, where the narrow arc lets you touch the puddle without melting through.
• Tack welding, with quick repeatable strikes and frequent restarts.
• Low-amperage starts on thin-wall tube and food-grade sanitary stainless fittings, where the joint must stay cool and clean.

Sanitary work is worth calling out. Dairy, beverage and pharmaceutical stainless must meet strict surface finish and sanitation criteria: no heat tint, oxidation or contamination. A lanthanated electrode gives a clean, controlled arc at the low amperages used on 16 to 20 gauge tube, and its non-radioactive nature matters in food plants with tight material controls.

Tube and pipeline work

Root passes on schedule 40 and schedule 80 stainless and carbon steel typically run 30 to 90 amps with a 1/16 in or 3/32 in electrode, and lanthanated starts reliably on vertical root passes where the strike angle is awkward. Filler passes then move into the 90 to 150 amp band with a 3/32 in tip. For thin-wall tubing of 3/16 in wall and smaller, most pipe errors come down to too much heat input, not too little electrode capability.

Sizes run from .020 in up to 1/4 in, and most shops stock three or four. Smaller diameters suit low-amperage arc starts, larger ones carry current without excessive tip erosion. Miller identifies 3/32 in as the versatile default, with 1/16 in for thin work and 1/8 in and larger for heavy plate.

Diameter	Typical amperage	Best suited for
.020 in	Up to 20 amps	Micro work, foil, delicate repair
1/16 in (1.6 mm)	20 to 80 amps	Thin sheet, precision TIG, tack welds
3/32 in (2.4 mm)	60 to 150 amps	Light gauge through 1/4 in and thicker
1/8 in (3.2 mm)	150 to 250 amps	Heavy plate, thick tubing
3/32 in to 1/8 in+	250 amps and above	Plate and pipe, deep penetration

AC balance and pulsed TIG

On aluminum, AC balance sets how much of each half-cycle goes into cleaning versus penetration. Most machines default the electrode-positive (cleaning) side near 60 to 70 percent, and lanthanated tungsten tolerates that ratio without tip erosion or spitting, so keep the standard setting and focus on travel speed and amperage.

With pulsed TIG, the pulse keeps the puddle small and heat input predictable, and a lanthanated tip stays stable across the rapid current swings, which suits thin-gauge aluminum and stainless where a constant arc would burn through. New to aluminum TIG? Our aluminum MIG welding guide covers the neighbor process, and the aluminum cleaner guide explains why surface prep decides whether any electrode succeeds.

Shop notes and bottom line

Standard tungsten length is 7 inches, with 7.5 in (180 mm) variants for specialty collets. Electrodes can be cut shorter for tight spaces or machines with shorter back caps, but never snapped, and abrasive-wheel trimming keeps the tip from developing the micro-cracks that cause erratic arcs later.

Purple tungsten does not change the limits of the process, which still needs clean base metal, correct polarity, adequate gas coverage and a properly sized cup. It widens the range of amps and materials where one electrode type starts reliably and stays stable, which for most shops is the difference between one tube of purple and a drawer of four colors.

Grinding and Preparing Purple Tungsten the Right Way

A new purple tungsten is not ready to weld with. It needs a point shaped to the job, and how you grind that point decides whether the arc behaves like a thin pencil beam or a spitting mess. Most “purple tungsten doesn’t work for me” complaints are preparation problems, not metallurgy problems.

Cut It, Never Snap It

Shorten an electrode with an abrasive cutoff wheel, or by snapping it against the corner of a grinding wheel. Never use wire cutters, and never bend and break it. Bending leaves hidden micro-fractures in the shank that will not fail today, but will fail the next time you push 150 amps through the tip, sending the arc wandering or spitting for reasons you cannot trace. Miller’s tungsten guide makes the same recommendation.

Grind Marks Must Run Down the Length

Grind marks must run parallel to the electrode centerline, and this is the rule most often broken. Miller warns that angled or spiral scratches cause an unstable arc. The plasma forms at the sharpest point of the tip, so longitudinal lines leave a symmetrical cone that anchors the arc predictably, while a spiral grind leaves a ragged edge the arc hunts along. Symptoms are a wandering arc, erratic bead width, and tip spitting. Set the wheel so it approaches the electrode from the side, along its length, and never roll the electrode in your fingers while grinding. A grinder with a shank rest takes out the guesswork.

Use a Dedicated Grinder and the Right Wheel

Use a grinder dedicated to tungsten so steel and other contaminants are not embedded in the electrode. A shared steel bench grinder is the worst option: ferrous particles lodge in the porous oxide surface of the tungsten, then melt into your weld and cause contamination that makes people think their machine is bad. Diamond wheels cut tungsten fast and leave a clean surface with minimal loading; green silicon carbide works but wears faster. Dedicate whichever you pick, and label it. A dedicated tungsten grinder with an adjustable point-angle fixture pays for itself in a high-volume shop, because it removes hand angle as the biggest source of inconsistency.

Choosing the Point Angle

The tip angle is your main control over arc character, and the setting most people never change.

• Sharper points give a wide, shallow arc for thin-material edge welding and low amperage work on stainless or aluminum sheet.
• Blunter points increase penetration and concentrate heat into the joint, which suits thicker stock.
• A small flat at the tip helps prevent spitting at very high amperage, where a needle-sharp point sheds molten metal.

Shop practice is roughly 20 to 30 degrees for thin material and 40 to 60 degrees for heavy plate. What matters is a symmetric point and longitudinal grind lines. For arc character by electrode type and angle, see the updated tungsten electrode guidelines from The Fabricator and the Diamond Ground tungsten guidebook.

Balling: Mostly a Thing of the Past

Old-school practice was to ball a pure tungsten tip into a rounded bead on AC with a transformer machine, because the round shape gives a stable, forgiving arc on aluminum. On modern inverters that habit mostly creates problems, since a balled tip on a DCEN job wanders or spits. Ball only where it still has a purpose: pure tungsten on transformer AC. The aluminum MIG welding guide covers the polarity and heat balance issues that trip up TIG welders doing the same work.

Step-by-Step Preparation Checklist

1. Inspect first. Straight electrode, no dents or bent shanks? Discoloration means corrosion, so discard it.
2. Size the diameter to the thinnest joint you will weld with that rod, not the thickest.
3. Clean the grinder. Dedicated tungsten wheel only, never a shared steel bench grinder.
4. Set the length. Leave about 1/2 inch projecting beyond the collet, plus extra for stick-out.
5. Grind longitudinally. Wheel to the side, marks parallel to the centerline, tip symmetric.
6. Check for cracks and slivers under a bright light, and feel along the shank for burrs.
7. Mark the ground end with a paint pen so you pick the right rod later.

Storage and Spares

Store electrodes somewhere dry, in their original packaging or a sealed tube. Moisture and oxidation degrade the tip, and the oxide layer that gives your arc its good behavior is exactly what a damp, open bag spoils. Keep pre-sharpened spares in a tube next to the machine, sized for the work you do most, so a bad tip can be swapped in seconds instead of reground mid-fit-up. Many shops pre-grind a batch to a standard angle for their most common job, but make sure the length suits the torch, since a rod too short for a long extension needs a second grind.

None of this is complicated, but it is the difference between a purple tungsten that performs like a premium electrode and one that gives you a bad reputation it did not deserve.

Setting Up Your TIG Rig Around a Purple Tungsten

Swapping in a purple electrode is the easy part. What decides performance is the torch around it: collet body, cup, gas flow, polarity and balance. Get those right and a 1.5% lanthanated tip feels forgiving. Get them wrong and even the best tungsten will spit and wander.

Gas Lens or Standard Collet Body?

A standard collet body uses the ceramic cup itself to shape the shielding gas. It is cheap, simple and fine for butt joints and flat work. A gas lens adds a separate nozzle that creates a wider, more laminar gas column: less turbulence, better shielding over a longer stick-out, cleaner welds on thin material and stainless tube.

The trade-off is cost and gas. Gas lens bodies want a bigger cup, and argon flow has to come down because the lens pulls in a lot of air. Miller’s tungsten and TIG setup guide recommends a gas lens where coverage matters most. Start with a standard body on flat plate, then move to a gas lens for tube, thin stainless or aluminum.

Cup Size, Flow Rate and Gas Coverage

With a standard collet body, argon flow of roughly 15 to 25 CFH is the working range. Larger number 6, 7 or 8 cups want the higher end; small number 4 and 5 cups and long stick-out want less, because you stir the air and create turbulence. With a gas lens, drop flow into the single digits to low teens.

Under-flow and you get oxidation, a dirty dull bead and a wandering arc. Over-flow and you rip the shield off the puddle, blowing the arc around on thin material. Set flow with a mechanical flowmeter and verify it at the cylinder, not the regulator. Our Airgas welding supplies guide covers regulator and flowmeter options, and AllGas welding supply explains cylinder sizes and grades.

Collet, Collet Body and Electrode Extension

Match the collet and the collet body to the electrode diameter. A collet sized for 3/32 in in a body machined for 1/16 in will not clamp, and a loose clamp makes the electrode wander and arc start erratically. A 3/32 in (2.4 mm) electrode is the shop default for most work.

Extension past the collet is the setup variable most people get wrong. Keep it minimal, roughly 1/8 to 1/4 inch, for precision work and thin material where you need a tight, focused arc. Expose slightly more, around 3/8 inch, on fillets or tube where you need to see the joint line. Every extra millimeter of exposed tungsten is unshielded.

Polarity, AC Balance and Starting the Arc

Use DCEN (DC electrode negative) for steel, stainless, titanium, copper and nickel alloys. Use AC for aluminum and magnesium. New to aluminum TIG? Our aluminum cleaner preparation guide covers cleaning and gas coverage.

On AC, the machine alternates a cleaning phase that scours the oxide with a penetration phase that drives heat into the metal. A purple 1.5% lanthanated electrode is forgiving here because its oxide dispersion handles both halves of the cycle. Set balance around 65 to 70 percent cleaning on aluminum. For deeper penetration, push balance toward penetration and raise amperage.

A high-frequency start is the modern default and the least aggressive on the tip. Scratch starting works, but the strike wears the point and can leave a cratered tip that arcs poorly. Without HF start, set a light preflow and make contact on scrap, not the workpiece.

Timing and Pulse

Run roughly one to two seconds of preflow before striking the arc and five to ten seconds of postflow after you finish, longer on aluminum or stainless. For thin material and heat control, pulse TIG is where a lanthanated electrode shines. Start near 30 to 100 pulses per second with a peak around double your average amperage, then adjust the ratio by hand until the puddle behaves.

Job	Electrode	Polarity	Gas / Flow	Setup notes
Thin stainless (0.6 to 1.2 mm)	1/16 in (1.6 mm)	DCEN	Argon, 10 to 15 CFH, gas lens	Minimal extension, HF start
Aluminum sheet (1 to 3 mm)	3/32 in (2.4 mm)	AC	Argon, 12 to 18 CFH, large cup	Balance to cleaning, long postflow
Mild steel plate (3 to 6 mm)	3/32 in (2.4 mm)	DCEN	Argon, 15 to 20 CFH	Standard body, 1/4 in extension
Tube and pipe	1/16 or 3/32 in	DCEN	Argon, 15 to 25 CFH, gas lens	More extension, back-purge if needed

Finally, check that the classification matches what you bought. AWS A5.12 lists 1.5% lanthanated under classification EWLa-1.5, and that printed code is the only reliable identifier once the box is open. Set the torch up properly, keep a spare prepared tip in your pocket, and the purple electrode does exactly what the label promises.

Benefits and Limitations of Purple Tungsten: An Honest Assessment

Any electrode recommendation that only lists upside is advertising, not information. Purple tungsten is a genuinely capable electrode, and in most modern shops it is the safest default on the shelf. It is also not the universal answer. If you know where it wins and where it merely ties the competition, you will spend money far more wisely.

The honest framing starts here: purple (AWSEWLa-1.5) belongs to the same family as the 2% lanthanated blue electrode that Miller positions as the true all-purpose electrode. Miller’s guidance holds for the 1.5% variant too. Same all-metal, all-polarity behavior, just marginally less oxide in the mix.

Where Purple Tungsten Earns Its Place

• No radioactivity to manage. Lanthanum is not a radioactive element, so a lanthanated electrode eliminates the residual radioactivity concern that comes with 2% thoriated (EWTh-2) tips. Shops that abandoned thoriated because of the paperwork can stop worrying about handling controls.
• Reliable starts on modern inverters. Square-wave and high-frequency starting is harder on electrode tips than old transformer machines. Purple tips ignite consistently cold, which matters most on a Monday morning job.
• All metals, both polarities. DCEN for steel, stainless, copper, titanium and nickel alloys. AC for aluminum and magnesium. One electrode type covers most of a general fabrication shop.
• Good low-amperage behavior. The oxide lowers the work function enough to establish an arc at lower current, so thin-gauge and precision work stays stable. That is why aerospace and instrument work often specifies lanthanated or ceriated tips, as detailed in our aerospace TIG welding guide.
• Reasonable service life. Purple holds its point through multiple grinds, so you are not constantly swapping electrodes mid-afternoon.
• Comparable pricing. Typically priced near blue lanthanated and only slightly above commodity pure tungsten, not in a different cost tier.
• Forgiving for beginners. Predictable arc behavior, decent tolerance of imperfect grinding, and no radioactive-material training hanging over the bench.

Where It Is Not the Automatic Answer

• Very low amperage on thin stainless: 2% ceriated (gray, EWCe-2) remains a favorite with many shops because it kindles at lower current and holds a tight arc on foil-thin material.
• Transformer AC on aluminum: Zirconiated (white, EWZr-1) and pure tungsten (green, WP) are still the traditional choices on old machines. Lanthanated works on AC, but it is not what an aluminum-focused shop has always run.
• High-amperage DC penetration: Thoriated still has advocates for heavy DC work and strong erosion resistance, though it comes with handling requirements because thorium is radioactive and is covered by OSHA welding and cutting rules. For heavy plate electrode strategy, see our alloy steel welding electrode guide.
• Automated low-current production: Rare-earth and chartreuse mixes are engineered for robotic and high-volume starts, and they are purpose-built rather than general-purpose.
• Casual hobby use: If you weld a bracket once a month on a small machine, the difference between purple and blue is a rounding error on your bill. Buy what is on the shelf.
• Availability: Purple is well stocked at distributors, but selection at small shops and online marketplaces is thinner than for green or blue.

Electrode	AWS class	Best at	Watch for
Purple (1.5% La)	EWLa-1.5	All-purpose shop default, non-radioactive, both polarities	Not the lowest-amperage specialist
Blue (2% La)	EWLa-2	Highest current capacity in the lanthanated family	Higher oxide load, shorter grind life than some purples
Gray (2% Ce)	EWCe-2	Very low current on thin stainless	Less capable at heavy DC work
Red (2% Th)	EWTh-2	High-amperage DC penetration	Radioactive, handling controls required
Green (pure)	WP	AC on aluminum, spooling, general AC work	Poorest arc starting and low-current behavior
White (zirconiated)	EWZr-1	AC aluminum on transformer machines	Less stable on DC than lanthanated

Price, Availability and the Oxide Content Reality

Electrode life and re-sharpenability vary noticeably by brand and by how much oxide is actually in the rod. Two purple boxes from two manufacturers are not chemically identical, so judge performance against your own weld results, arc stability and tip wear rather than against a spec sheet. Industry guidance on electrode selection and oxide chemistry is worth reading in full, including the updated guidelines for tungsten electrodes from The Fabricator.

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Safety, Radioactivity and Handling: Why Welders Switch to Purple

Ask a shop owner why they moved off red-banded electrodes and you rarely hear about arc performance first. You hear about paperwork. Red tungsten contains thorium, and thorium-232 is a radioactive element with a half-life of roughly 14 billion years. A 2% thoriated electrode is not the hazard most people imagine, but most jurisdictions treat it as a low-level radioactive material, which brings storage records, disposal manifests and headaches for shops that also take aerospace or medical work. Purple tungsten deletes that entire category of compliance work, and for many shops it is the deciding factor.

What “2% Thoriated” Actually Contains

The 2% refers to the percentage of thorium dioxide (ThO2) blended into the tungsten, and the specification allows roughly 1.8% to 2.2% of that oxide. Thorium-232 is a naturally occurring radionuclide that decays through a long chain of alpha and beta emitters. Because it is primarily an alpha emitter, the concern is not the glowing tip sitting in your collet, it is what happens when you grind the electrode and the dust goes into the air. Current industry guidance, including The Fabricator’s update on tungsten electrode guidelines, reflects how completely the market has moved away from red for exactly this reason. Electrode identities and classifications are standardized under AWS A5.12, which is where the EWTh and EWLa designations come from.

What the Measurements Actually Show

The reassuring part of the story is that measured exposures are small. Research presented at the ninth IRPA congress measured airborne thorium-232 activity of up to 2.6 mBq/m³ during proper use of thoriated electrodes. Most assessments built on that evidence conclude the external dose a welder receives from holding or welding with a thoriated electrode is a very small fraction of the applicable permissible limits. The credible exposure route is not the arc and it is not the tip. It is inhalation or ingestion of fine grinding dust, which is why the controls below all cluster around the grinder and the bench.

The OSHA Framework

Two rules matter in the United States. 29 CFR 1910.1096 is the standard for ionizing radiation, setting exposure limits, survey and notification concepts, and the general duty to keep exposure as low as reasonably achievable. 29 CFR 1910.252 covers general requirements for welding, cutting and brazing, including ventilation, eye and face protection, and hot work practices. Together they are the framework an employer’s safety professional works from when thoriated consumables are in the building.

Practical Controls If You Still Keep Red in the Shop

• Dedicated grinding station. A grinder used only for tungsten, ideally with a point or enclosure, plus local exhaust ventilation at the hood. A shared grinder means thoriated dust contaminates every other blade, wire wheel and tool in the shop.
• Wet cleaning, not dry sweeping. Damp wipe cloths or a wet method keep dust from becoming airborne. Compressed air and dry sweeping push fine particles straight into the breathing zone.
• No food, drink or smoking at the bench. Basic industrial hygiene, but the single biggest reason internal exposure stays rare.
• Appropriate PPE. Eye protection for grinding, plus respiratory protection where your risk assessment calls for it. Handling and PPE guidance is worth comparing against practices in alloy steel welding electrode selection and safety.
• Segregated storage and disposal. Store thoriated electrodes in labeled, closed containers away from general stock, and dispose of used tips and collected dust as low-level radioactive waste where your rules require it. Expect paperwork.

Why Purple Simplifies All of This

Lanthanated electrodes contain no radioactive alloying oxide at all. The lanthanum oxide added to purple and blue tungsten is stable and non-radioactive, so there is no radiation survey, no special waste stream, no labeled storage and no transport paperwork. Ground tips become ordinary metal swarf for the regular scrap bin, which means one dedicated grinder can serve every tungsten in the drawer instead of a second quarantined machine. For shops working under the documentation culture of aerospace and other regulated welding programs, that simplification is worth real money in avoided administrative time.

Switching to purple does not make welding safe on its own. The arc is still hot, the fume is still a concern, and a purple tip still needs a clean grinder so you do not contaminate the arc. What it does is remove the one consumable in the cabinet that asks your safety department for permission every time somebody opens a new box.

Common Purple Tungsten Mistakes and Troubleshooting

Here is the uncomfortable truth about purple tungsten: the oxide alloy is almost never the culprit when an arc misbehaves. Erratic arcs trace back to a contaminated tip, a bad grind, a mismatched electrode diameter, or a dirty work surface. Purple, blue, red and gray share the same failure modes, because the physics of a tungsten tip is the same regardless of color band. The Miller guide to tungsten selection and use lists most of the usual culprits, and once you can name the symptom, the fix usually takes under a minute.

Symptom, cause, fix: the fast diagnostic

Symptom	Likely cause	Fix
Arc wanders, spits, or dies seconds after striking	Tip contaminated by molten puddle, filler rod, or base metal	Swap in a clean pre-sharpened electrode and clean the joint
Arc strikes but will not hold a steady column	Grind scratches circling the tip, or a wheel used for steel	Regrind on a dedicated tungsten wheel, scratches parallel to the centerline
Wide, soft, sluggish arc on thin material	Electrode diameter too large for the amperage	Step down one diameter size
Tip balls up, spits, or crumbles at high current	Electrode diameter too small for the amperage	Step up in diameter, shorten the stick-out
Arc is noisy, tungsten oxidizes almost instantly	Poor gas coverage, wrong cup size, excessive stick-out	Bigger cup or gas lens, correct the extension
Arc pushes the puddle and the bead looks dirty on aluminum	Wrong polarity or an electrode mix that does not suit AC	Confirm DCEN and the AWS classification on the box
Weak, wandering arc on stainless or nickel	Mill scale, oil, or zinc-plated parts left on the joint	Degrease and mechanically clean before tacking

The three contamination habits that kill tips

Miller names three classic ways a TIG tip gets fouled: the electrode touching the molten puddle, the filler rod contacting the hot tungsten, and impurities transferred from the base metal. Each deposits something the arc dislikes, and the result is the same wandering, spitting arc you suddenly blame on the brand of tungsten.

Never dip the electrode into the puddle to start a pass, keep filler rod off the tip, and clean the workpiece before you light up. On aluminum, that prep step matters more than most people expect, which is why a good aluminum cleaner guide is worth keeping on the bench. In quality-critical work likeaerospace TIG welding, contamination control is not optional, and the same habits apply at any skill level.

Grinding mistakes that cause erratic arcs

Erratic arcs most often trace to spiral or angled grind scratches, or to a contaminated shared grinder, rather than to the oxide type. Scratch direction matters because the arc follows the grain of the tip, so scratches must run parallel to the electrode centerline. The Diamond Ground tungsten guidebook is worth reading once, since it covers wheel choice and point geometry in plain terms.

• Use a dedicated grinder for tungsten only, or a wheel reserved for non-ferrous work.
• Grind on a wheel corner with light pressure to avoid heating and work-hardening the tip.
• Never cut electrodes with wire cutters or snap them by hand. Micro-cracks become arc centers later.
• Point angle follows the job: a sharper point gives a wider, softer arc for thin edge work; a blunter point drives deeper penetration on thicker material.

Diameter, stick-out and the wrong box

Match the electrode to the current, not the other way around. Too small at high amperage and the tip balls, spits and erodes. Too large at low amperage and the arc starts wide and weak, and you lose control of the puddle. For amperage ranges by diameter, see the diameter guide earlier in this article.

Excessive stick-out is the other quiet killer. Every extra millimeter of tungsten outside the collet is a millimeter the gas shield has to cover. Past a reasonable extension, shielding breaks down and the arc oxidizes faster than it should.

Finally, confirm what you actually grabbed. Purple is 1.5% lanthanated and blue is 2% lanthanated, and while color codes are broadly consistent, they are not fully standardized between suppliers and regions. The AWS classification printed on the box is the reliable identifier, and AWS A5.12 defines the grades you should see.

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Buying Purple Tungsten: Sizes, Packs, Verification and Final Verdict

The technical case for purple tungsten is made, so the practical question is simple: what do you order, and how do you confirm the box matches the label? Tungsten is among the least complicated consumables to buy: three diameters, two lengths, a handful of pack counts. The real work is reading the label.

Sizes, Lengths and How Purple Tungsten Is Packaged

Standard electrodes come in 1/16 in (1.6 mm), 3/32 in (2.4 mm) and 1/8 in (3.2 mm), mostly in 7 in lengths, with 7.5 in / 180 mm variants also common. Pack counts run 2, 10 and 25 pieces: two-packs are a trial size or single-job buy, 10-packs suit a working shop, and 25-packs are the value pick for anyone who grinds tips regularly.

Diameter	Metric	Typical Role	Common Pack Sizes
1/16 in	1.6 mm	Thin sheet, tube, low amperage, precision work	2 / 10 / 25
3/32 in	2.4 mm	Versatile default for most shop work	2 / 10 / 25
1/8 in	3.2 mm	Heavy plate and high-amperage capacity	2 / 10 / 25

Match diameter to current rather than habit. Smaller tips make low-amperage starts easier and give finer control; larger tips carry more current before they spit. Miller recommends a 3/32 in 2% lanthanated electrode as an all-purpose default, and the 1.5% purple variant is the closest non-radioactive sibling. If unsure, buy 3/32 in and add 1/16 in for thin work later. The Diamond Ground tungsten guidebook walks through the differences.

Where to Buy

Welding distributors and gas suppliers such as Airgas welding supplies and regional supply houses are the safest route: they stock fresh product, keep batch consistency, and can tell you which brand is on the shelf. Online marketplaces work for price comparison, but the risks there are counterfeit or relabeled product, old stock with degraded packaging, and mixed lots. Buy there only when the listing names the manufacturer and shows the AWS classification.

What to Check When the Box Arrives

• The AWS classification. For purple tungsten you want EWLa-1.5 printed on the box or bag, per the lanthanated electrode standard in AWS A5.12. Confirm the printed classification rather than band color alone, since color conventions vary by region.
• Straightness. Electrodes should be straight along their length. Bent or kinked ones will not grind into a concentric point and arc unpredictably.
• Tip condition. Factory-ground tips should be conical, even and chip-free. If you grind your own, buy unground or broken-tip stock and prepare it properly.
• Pack integrity. Check for corrosion, scuffing or a broken seal. Storage details are in Miller’s guide to tungsten selection and use.

What It Costs Compared to Red, Blue and Gray

Pricing tracks oxide content more than color. Red thoriated and gray ceriated are usually cheapest; blue 2% lanthanated sits a little higher; purple 1.5% lanthanated typically lands near blue, sometimes a touch above. Pure green and zirconiated white sit in the same band. Expect a few dollars per pack in differences, not multiples, which is trivial next to the paperwork thoriated electrodes create.

So Which Electrode Should You Actually Buy?

• Buy purple (EWLa-1.5) if you want a non-radioactive, all-purpose electrode on a modern inverter and work across steel, stainless, copper, titanium, aluminum and magnesium.
• Choose blue 2% lanthanated if you want maximum general-purpose current capacity in one electrode and heavy high-amperage work.
• Go gray ceriated if you mostly weld thin stainless at very low current.
• Use white zirconiated or green pure if you run transformer AC on aluminum. For the broader aluminum picture, see the aluminum MIG welding guide and how to prep aluminum correctly.
• Choose red thoriated only where shop policy permits it and you want its high-amperage DC penetration and erosion resistance. The alloy steel welding electrode guide covers tube, pressure and aerospace work.

Key Takeaways

Purple tungsten is a 1.5% lanthanated electrode, AWS EWLa-1.5, and it earns its place in most shops because it does three things at once: it starts cleanly, it works on every common metal in DC and AC, and it carries no radioactivity. Order 1/16 in, 3/32 in and 1/8 in in 7 in lengths, buy packs of 10 or 25 if you grind your own tips, and confirm the printed classification rather than trusting the band color. For setup details, revisit The Fabricator’s tungsten electrode guidelines and the Weldguru TIG tungsten electrode guide, then read on for the questions fabricators ask most.

Disclosure: Some links in this article point to product and supplier guides that may earn us a commission at no extra cost to you.

Next up: frequently asked questions about purple tungsten, from arc-start myths to whether it beats blue.

Frequently Asked Questions

What is purple tungsten used for in TIG welding?

Purple-banded tungsten is 1.5% lanthanated tungsten (AWS EWLa-1.5), used as a general-purpose, non-radioactive electrode for GTAW. It runs on AC and DC, so it welds mild steel, stainless, aluminum, nickel alloys, copper and titanium with stable arc starts across a wide amperage range.

What is the difference between purple and blue tungsten?

Both are lanthanated tungsten; purple is typically 1.5% lanthanum oxide while blue is 2%. The 2% blue version is slightly more aggressive with marginally higher current capacity, while purple tends to give a somewhat finer, gentler arc and slightly slower tip erosion. Weldability is otherwise very similar.

Is purple tungsten radioactive?

No. Lanthanum oxide is not radioactive, which is the main reason welders switch to purple or blue from 2% thoriated (red) electrodes, which contain radioactive thorium-232 and require stricter handling and grinding controls.

Can I use purple tungsten on aluminum with AC?

Yes. Lanthanated electrodes work on AC as well as DC, and they handle both the cleaning and penetration phases of the AC cycle. Many welders use purple or blue tungsten on aluminum as an all-purpose alternative to zirconiated (white) or pure (green) tungsten, especially on inverter machines.

How do I grind purple tungsten correctly?

Grind with a wheel or belt dedicated to tungsten, keeping every scratch parallel to the electrode’s centerline so the arc stays stable. Cut electrodes with an abrasive cutoff wheel rather than wire cutters to avoid micro-cracks, and use a sharper point for thin material and a blunter point for deeper penetration.

What diameter purple tungsten should I buy?

A 3/32 in (2.4 mm) electrode is the versatile starting point for most work, from light sheet to 1/4 in and thicker material. Move to 1/16 in (1.6 mm) for low-amperage thin work and to 1/8 in (3.2 mm) or larger for heavy plate and high current.

Does purple tungsten last longer than thoriated?

In practice, lanthanated electrodes re-sharpen well and resist erosion reasonably, but real life depends on amperage, contamination and grinding habits. Welders who keep spare pre-sharpened tips on hand and avoid touching the puddle get far longer service than any electrode type used carelessly.

Why does my purple tungsten turn black or ball up?

A blackened or balling tip usually means the electrode touched the puddle, the filler rod contacted the tip, or the diameter is too small for the current. Replace or regrind the tip, increase diameter if you are running hot, and check gas coverage and base-metal cleanliness before blaming the tungsten.

Is purple tungsten worth buying over blue or gray?

If you want a single non-radioactive electrode for mixed AC/DC work on a modern inverter TIG machine, purple is an excellent choice. Choose gray ceriated if most of your work is low-amperage stainless, and blue 2% if you want the most common general-purpose lanthanated option.