Answer
For steel tubing before paint, use 180 or 220. Use 120 first only for rust or scale, then 320 before primer.
Why it happens
Steel tubing needs rust removal, cleaning, and an even scuff pattern before primer.
Recommended grit
Use 180 or 220 for general scuffing. Use 120 first for rust or scale, then finish with 320 before primer.
Wet or dry
Dry.
Success check
The steel tube is clean, dull, and evenly scuffed before primer.
What to do
- Clean oil and dirt from the tubing.
- Use 120 only for rust or scale.
- Scuff the full tube with 180 or 220.
- Use 320 for finer primer prep.
Avoid: Do not paint over oil, rust, or shiny unsanded steel.