Clean TIG welds separate professional fabrication from work that gets rejected at inspection. Across the Australian building and construction sector, contaminated welds cost real money in rework, failed inspections and lost contracts. Fortunately, most contamination traces back to a handful of preventable habits. Porosity is one of the most common TIG welding defects, and it reduces strength, toughness and corrosion resistance. It is almost always caused by gas entrapment from contaminated base material, dirty filler rods or poor shielding. In short, the fix starts before the arc ever strikes. This guide walks through the four pillars of clean TIG work: material prep, gas coverage, tungsten care and heat control, plus post-weld cleanup for stainless.
Step 1: Prepare the Material Properly
Everything on the surface of the metal ends up in the weld pool. Oil, paint, grease, rust and mill scale all cause defects, so remove them completely before starting. Begin by degreasing. Wipe the base metal and filler rods with acetone and a clean rag to remove oils and residues that a wire brush would simply spread around. Next, strip the oxides. Use a dedicated stainless steel wire brush, Scotch-Brite pad or grinder to remove rust, mill scale or heavy aluminium oxide layers. It is also worth cutting cleanly. Abrasive cut-off wheels embed particles in the edge, so use a cold saw or band saw instead, then dress the edges with a file. Finally, aim for a tight fitup.
Work towards zero gap or a snug joint, and tack every 20 to 25 millimetres to prevent warping and erratic gaps as heat moves through the part. Filler rod storage matters too. Rods kept in damp conditions pick up moisture and introduce hydrogen into the weld pool, so store them dry and wipe them down before use.
Step 2: Get the Gas Shielding Right
Argon does the invisible work in TIG welding. Commercially available welding argon typically runs at a purity above 99.996 per cent, which means total impurities top out around 40 parts per million. That level of purity exists for good reason. Even trace moisture in the shielding gas creates serious welding flaws. Here is how to make the most of it.
First, run 100 per cent argon for standard TIG work and skip mixed gases. Then set the flow to 15 to 20 CFH for aluminium, or match the flow rate to your cup size for steel. Additionally, block any drafts before you start, as fans, open roller doors and breezes strip the gas bubble off the puddle. For stainless and aluminium, set post-flow to 6 to 8 seconds so the hot tungsten and weld puddle cool under argon coverage. It is also worth upgrading to a gas lens. Swapping the standard collet body for a gas lens improves coverage and lets you run a longer tungsten stickout in tight joints. A common assumption is that more gas equals more protection. In practice, however, excessive flow creates turbulence that pulls airborne contaminants into the weld zone and causes arc wandering. When in doubt, err on the lower side of the recommended range.
Step 3: Look After Your Tungsten
The tungsten electrode shapes the arc, and a poorly prepared electrode produces a poor weld. This step is commonly overlooked, yet it makes a significant difference to weld quality. Grind lengthwise, never across. Grinding direction directly affects arc stability. When electrodes are ground crosswise, electrons have to jump across the grinding marks. As a result, the arc starts before the tip, spreads out and wanders. Longitudinal grinding leads electrons steadily to the point, so the arc starts straight, stays narrow and remains stable.
Use a dedicated grinder with a diamond wheel. Aluminium oxide wheels leave jagged edges and imperfections that are invisible to the eye, and those flaws show up later as weld inconsistency and defects. Inspect before every arc strike. A contaminated tungsten produces an erratic arc and a contaminated weld. If you dip the tungsten in the puddle or touch the filler wire, stop and re-grind or swap it immediately. Continuing with a dipped electrode transfers contamination straight into the bead. Match the tungsten type to the job. A 2 per cent lanthanated electrode set up to spec covers most steel and stainless DC work.
Step 4: Control Your Heat and Technique
With prep, gas and tungsten sorted, technique determines the final result. Start with foot pedal control. Ease into the arc, establish a smooth puddle, then back off the amperage as the weld washes out. The part heats up as you travel, so the current that started the weld will overheat the end of it. From there, focus on feeding filler smoothly. Add the rod into the edge or centre of the pool.
Jamming it in or melting it in the raw arc cone without an established puddle produces contamination and inconsistent beads. Throughout the run, keep travel speed consistent. Let the heat soak properly without overheating the heat-affected zone, as excess heat in the HAZ causes warping and metallurgical changes that weaken the joint. Consistency here comes from repetition. Practice on offcuts of the same material and thickness before committing to the job.
Step 5: Clean Up Stainless After Welding
On stainless steel, the job continues after the last pass. Heat tint left on the surface reduces corrosion resistance, so remove it and restore the passive layer before calling it done. For electrolytic cleaning, use an electrochemical weld cleaner such as a TIG Brush with cleaning fluid to remove heat tints and passivate the weld safely. Alternatively, pickling paste (K2 paste) works well as a chemical option. However, Australian WHS regulations strictly require full PPE, including a respirator and heavy-duty chemical gloves, as well as a neutralising rinse after application, given the extreme toxicity of the hydrofluoric and nitric acid blends typically used. For less critical work, gentle buffing with a Scotch-Brite pad or a dedicated stainless brush improves the finish as a mechanical option.
The Bottom Line
Clean TIG welds come from process discipline. Degrease and fit the material properly, run pure argon at a sensible flow rate, keep the tungsten sharp and clean, control heat with the pedal and finish stainless with proper post-weld cleaning. For Australian fabricators, this discipline pays off well beyond appearance. Standards such as AS/NZS ISO 3834 set the benchmark for welding quality across the industry, covering everything from design through to inspection. Shops that build these habits into everyday work produce welds that pass inspection the first time, and that reputation wins repeat work. Start with the prep bench, and the rest follows.
