How to remove varnish<br>Create good ventilation. Whether your sanding or using a chemical solvent, it's a good idea to have ventilation. Open windows and use fans to create cross-ventilation if you're inside.
Varnish removal is even easier for window sills when there is adequate cross ventilation. 
( z1 easy :ARG1 ( z2 remove :ARG1 ( z3 varnish ) ) :mod ( z4 even ) :beneficiary ( z5 sill :part-of ( z6 window ) ) :condition ( z7 adequate :domain ( z8 vent :ARG0-of ( z9 cross ) ) ) :ARG2-of ( z10 have-degree :ARG1 z2 :ARG3 ( z11 more ) ) )