Also sand the sides and ends of the boards, but be sure to follow the grain! The ends can be particularly rough and coarse. For these, use 80-grit sandpaper. [3] X Research source
Oil-based polyurethane varnish takes about 6 hours to dry, and water-based varnish takes about 24 hours. [9] X Research source Be sure to note which kind you have, and allow enough time for it to dry completely between applications.
Use polyurethane varnish on the sides and another sealant on the broad faces of the board if you’d like a different finish for the broad faces of the board. If you do this, use masking tape to protect the faces of the board, since other sealants won’t apply well on top of polyurethane varnish. [10] X Research source
Turn the board over to make sure the oil has saturated all the way through to the back. If it hasn’t, repeat this step on the back of the board.
There’s no need to wait for the board to dry with this method, since the oil works simply by saturating the board before any water can. Oil and water don’t mix, after all![21] X Research source
Be sure to use an epoxy that indicates it’s suitable for use on wood. Most products labeled “epoxy resin” should do, though it’s best to choose a product advertised for wood in particular, such as tabletop resins, which are designed for use in kitchens.
As the epoxy cures and becomes tacky, pass a hair dryer over the surface to remove any air bubbles. [26] X Research source
Once the epoxy has cured for at least a week, you can repeat this process on the backside of the board if desired.
