TIG welding: the complete beginner's guide

TIG welding is one of the most beautiful and cleanest ways to join metal, but it is also a technique you need to practise a little. This guide walks calmly through everything a beginner needs to know: what it is, what you need, how to set it up and how to keep the weld pool under control.

What is TIG welding?

In TIG welding (Tungsten Inert Gas, also called GTAW) an arc burns between a tungsten electrode and the workpiece. The electrode itself does not melt. The weld pool is protected by an inert gas, usually argon, which flows from the TIG cup around the electrode. When needed you add filler rod with your other hand.

TIG welding gives neat, clean welds without spatter. That is why it is widely used for stainless steel, aluminium, titanium and thin steel, and wherever the weld is visible.

What do you need?

A TIG welding machine with DC for steel and stainless, and AC/DC if you want to weld aluminium. A foot pedal or torch switch to control the current helps enormously.
A TIG torch (WP9, WP17, WP18 and WP26 are commonly used), with matching parts.
Argon (100%) from a gas cylinder with regulator and hose.
A tungsten electrode. Read how to choose the right colour.
A TIG cup (gas nozzle). Read how to choose the right cup size. Take a look at our welding cups.
A gas lens for a calmer gas flow and more stick-out. Read what a gas lens does.
Filler rod that suits the material you weld.
Protection: welding helmet, TIG gloves, welding jacket and good ventilation.

Setting up the machine

Polarity: for steel and stainless you weld on DC with the electrode negative (DC minus). For aluminium you use AC.
Gas: argon, roughly six to twelve litres per minute. The right amount depends on the cup size and on draughts in your workshop. Too little gives poor coverage, too much makes the gas flow unsettled.
Current: start low and build up. As a first rule of thumb for steel, use about thirty to forty amperes per millimetre of material thickness, but always check the instructions of your machine.
Grinding the electrode: for DC you grind a point, lengthwise along the electrode, about two to three times the diameter in length.

The technique

1. Clean the workpiece. Remove grease, paint, rust and, on aluminium, the oxide layer. Contamination is the biggest cause of poor welds.
2. Hold the torch at an angle of about ten to twenty degrees to the welding direction.
3. Keep the arc short. About the diameter of the electrode is a good distance. A long arc gives an unsettled weld.
4. Let the weld pool form before you add filler rod. Add the rod at the front of the weld pool and do not pull it out of the gas while you move.
5. Move evenly. Wait until the weld pool shines, then move a little. The rhythm comes with practice.
6. Let the gas flow after the weld until it has cooled, so the electrode and the weld do not oxidise.

By material

Steel: the easiest start. DC, argon, clean material.
Stainless: sensitive to oxidation. Good gas coverage matters, and when welding through a pipe or plate you need back purge gas on the inside. A gas lens helps.
Aluminium: AC, extra cleaning and a slightly bigger cup.
Titanium: very sensitive to air, even while it is still cooling. Read titanium welding and gas coverage.

Common mistakes

The electrode touches the weld pool and gets contaminated. Grind it again.
Too little or too much gas.
Dirty material or dirty filler rod.
Too long an electrode stick-out without a gas lens.
Trying to go too fast. An even pace gives the best weld.

Parts that make the difference

Your weld does not depend on technique alone. Good cups, a gas lens and a sharp, clean electrode make welding easier and the weld nicer. Not sure which parts fit your torch? Use our selection guide or send us a message through the contact page.

Safety

Always weld with a welding helmet with a suitable filter, gloves and flame-retardant clothing. Make sure you have extraction or good ventilation, especially on stainless and coated materials. Do not work with flammable substances nearby.