Answer
Remove old varnish with 80 or 120, then refine the wood with 180 and 220 before new finish.
Why it happens
A fine grit may polish the varnish instead of cutting through the old finish.
Recommended grit
Use 80 or 120 for old varnish removal, then 180 and 220 for wood prep.
Wet or dry
Dry.
Success check
Old varnish is removed and the wood is refined through 220.
What to do
- Start with 80 or 120 only where varnish needs removal.
- Sand evenly without digging into the wood.
- Refine with 180.
- Finish wood prep with 220 before applying a new finish.
Avoid: Do not leave coarse removal scratches before refinishing.