White powder in grain after wet sanding poly

[Todd Bryant]

I put on some poly on an oak project I am working on and it was fairly rough from dust nibs and such. I read once about wet sanding between coats using mineral spirits. I have dry sanded before and got lots of corns, so I thought I would give it a try. It worked great, but left a white, slightly oily, powdering residue (as I expected). It all wiped off ok, but some is in the grain of the oak and it won't come out. I tried blowing it out with an air compressor and it won't budge. Any tips on getting it out? If I put another coat on top of this will it still be visible?

I would also be interested in whether there is a better technique to smooth out poly between coats. Thanks!

[Steve Schoene]

I think your best approach is likely to be wiping with copious amounts of naphtha to "float" it out of the pores. You are right "poly" doesn't sand very well. But then, it's a finish for floors, to borrow from Scott. If you wet the surface with the naphtha you will see to what extent the next coat would hide the sanding swarf.