Expert Answers: Clear Filling for Wood

Want to seal a large natural hole in a piece of wood while still preserving the rustic appearance? HANDY has the answer.

Q: The board that I’m using for the top of a cabinet has a large hole; it looks like a branch of the tree was connected at that point. I’d like to use a clear filler that preserves the hole so we can appreciate its depth and texture. What’s the best approach? - Jean Lewis, Des Moines, IA

A: Bob Tiesberg and his crew at Ancientwood in Ashland, Wisconsin, frequently work with pieces of wood that feature natural gaps and holes, which they fill with clear two-part resin. They prefer West System No. 105 Epoxy Resin and No. 207 Special Coating Hardener Clear Coat, but similar resins made by manufacturers such as System Three and MAS Epoxies also work well. Look for a hardener component that specifically features clear or no-blush characteristics. You can usually find these products at marine-supply stores, woodworking stores and craft stores.

Before applying the filler, clean the hole and use wax paper or paraffin to block any openings that will allow the resin to flow out. (The resin will not stick to wax.) Next, mix enough resin to fill in the hole no more than 1/4 in.; you’ll need to apply 1/4-in. layers to avoid trapping air bubbles and minimize the heat that the epoxy generates. After each layer dries, apply additional layers until the hole is filled slightly above the top.

You can also create interesting effects by placing decorative objects in the opening — Bob recently used seashells (pictured) — and pouring resin around them. Objects placed in partially cured layers of resin will appear to float in the cured finish.

Once the final layer has cured, sand the resin flush with the surface of the board and then apply three coats of clear varnish. The resin will look a little cloudy after sanding, but it will be clear after the varnish cures. - HANDY