Answer
For deck rails, use 80 or 100 on rough areas, then 120 or 150 before stain.
Why it happens
Outdoor wood needs enough sanding to remove roughness without over-polishing the grain.
Recommended grit
Use 80 or 100 for weathered rough areas, then 120 or 150 before stain.
Wet or dry
Dry.
Success check
The rail feels smooth but still accepts stain evenly.
What to do
- Clean and dry the wood first.
- Use 80 or 100 on rough weathered areas.
- Refine with 120 or 150.
- Remove dust before applying stain.
Avoid: Do not sand deck rail too fine before stain.