Key Takeaways

• Contamination is usually caused by air exposure or dirty surfaces
• Tungsten condition directly affects arc stability
• Shielding gas problems are a top cause
• Cleanliness is critical for TIG welding success

What’s Causing the Problem

1) Poor Shielding Gas Coverage

• Gas flow is too low or disrupted
• Drafts pulling shielding gas away
• Leaks in hoses or fittings

2) Dirty Base Material

• Oil, grease, oxidation, or coatings
• The aluminum oxide layer was not removed
• Stainless contamination from improper tools

3) Contaminated Tungsten

• Touching the puddle or filler rod
• Improper grinding direction
• Using the wrong tungsten type for the job

4) Incorrect Gas Flow Settings

• Too low → inadequate shielding
• Too high → turbulence pulling in air

5) Bad Technique

• Long arc length exposing the weld to the atmosphere
• Improper torch angle
• Inconsistent filler rod feeding

How to Fix It

Step 1: Set Proper Gas Flow

• Typical range: 15–25 CFH (7–12 L/min)
• Use lower end indoors, higher if needed for coverage

Step 2: Clean the Material Thoroughly

• Use a dedicated stainless steel brush for aluminum/stainless steel
• Remove all oil and grease with acetone
• Grind or wire brush to clean the metal surface

Step 3: Prepare Tungsten Correctly

• Grind longitudinally (not around)
• Keep a sharp, clean point for DC welding
• Replace tungsten if contaminated

Step 4: Check Equipment

• Inspect gas lines and connections for leaks
• Clean the nozzle and check the gas lens if installed
• Ensure proper cup size for coverage

Step 5: Improve Technique

• Keep arc length short and consistent
• Maintain proper torch angle (~10–15°)
• Feed the filler rod smoothly without touching the tungsten

Common Mistakes to Avoid

• Welding on dirty or oxidized metal
• Letting tungsten touch the weld puddle
• Running gas flow too high or too low
• Using contaminated filler rods
• Ignoring drafts in the work area

Best Settings / Guidelines

Always verify with your machine settings and material requirements.

Safety Notes

• Wear proper eye protection (ANSI Z87.1) and a welding helmet
• Avoid breathing shielding gas in confined areas
• Use proper ventilation when cleaning with solvents
• Keep gloves clean to prevent contaminating filler rods

FAQ

Why does my tungsten turn black?
This usually indicates poor shielding gas coverage or contamination.

Can I reuse contaminated tungsten?
Yes, but it must be re-ground properly before reuse.

Does gas type matter for contamination?
Yes—pure argon is standard for TIG and provides proper shielding.

Why is aluminum more prone to contamination?
Aluminum forms an oxide layer that must be removed before welding.

Can drafts really affect TIG welding?
Yes—even small air movement can disrupt shielding gas.

Sources Checked

• American Welding Society
• Lincoln Electric TIG welding resources
• Miller Electric application and troubleshooting guides