Answer
Remove thick caulk first, then sand residue with 180 or 220 and finish with 320 before paint.
Why it happens
Caulk residue can smear or sit above the surface if it is not removed before paint prep.
Recommended grit
Use 180 or 220 after removing the bulk of the caulk. Use 320 for final paint prep.
Wet or dry
Dry.
Success check
The area feels smooth with no raised residue before paint.
What to do
- Remove the bulk of old caulk first.
- Sand remaining residue lightly with 180 or 220.
- Feather the surrounding paint edge.
- Finish with 320 before primer or paint.
Avoid: Do not rely on sandpaper alone to remove thick caulk beads.