What is recommended before TIG welding aluminum to prevent porosity?

• A. Use a carbon steel brush
• B. Use a dedicated aluminum-capable stainless steel brush, followed by solvent degreasing
• C. Use a wooden brush
• D. Use water only to clean

Answer: (B)

The key idea is that porosity in TIG welding aluminum often comes from surface contaminants and oxide film that must be removed cleanly before welding. Aluminum forms a tenacious oxide layer that, if left on the surface, can trap hydrogen in the weld and create porosity. To prevent this, you need a cleaning method that removes that oxide without introducing new contaminants.

Using a dedicated aluminum-capable stainless steel brush is essential because it effectively scrub away the aluminum oxide without depositing iron or other metals into the weld area. A carbon steel brush would contaminate the surface with iron, which can promote inclusions and porosity; a wooden brush can shed fibers, and water-based cleaning can leave moisture that contributes hydrogen in the weld pool. After brushing, a solvent degreaser removes oils, fingerprints, and hydrocarbons that can also release hydrogen when heated. The combination of oxide removal plus degreasing gives a clean, dry surface for a sound weld.

So, the recommended practice is to clean with a dedicated aluminum-capable stainless steel brush, followed by solvent degreasing, to minimize porosity risk in TIG welding aluminum.