You can try a scotch-brite pad to make sure the surface is really clean and it will scratch the surface slightly. Probably getting down into the dimples a little better than straight sandpaper.

Because the inside does not get as much sun or wear as the outside, the varnish can afford to be less well adhered to the resin.

> Just finished the inside of my boat - one layer of glass with one coat of
> epoxy. I am planning to leave the weave unfilled to create a non-skid
> effect.

> Question: In the past I have always roughed up the epoxy with sandpaper
> before varnishing. Is this necessary? The epoxy is fairly rough due to the
> weave of the glass - and the sanding tends to be very superficial, hitting
> only the high spots. Can I get away without sanding the epoxy first?

> Thanks.