I would use a good brush not foam. I wouldn't sand with paper between coats just a scotch brite type pad to knock of the high points. Are you certain the wood was good and dry before the first coat? ow many coats have you applied? Uneven sheen is off if the wood was dry. The first and second coat will give a good seal. The third and forth will build up. Probably know this but tack it off well between coats.