How to Fix Cracks in Wood
Even though you may have tried to use wood without any cracks, splits, holes, or gouges, sometimes you end up with imperfections you didn’t notice or couldn’t avoid. You can fill cracks, scratches, or even slightly mismatched joints with several different products, including wood putty, wax sticks, and shellac sticks. Each of these items has its strengths and weaknesses:
Wood putty: Wood putty comes as a thick paste that you spread into the hole or crack with a putty knife and then let dry and sand flush. It’s available in a variety of colors, so you’re sure to find one to match the wood you’re working with. If you can’t find a match, either add some stain to the putty while it’s still soft (before you apply it) or paint on some artist’s paint to match the wood’s surface after you sand it.
Wax sticks: Wax sticks are like crayons, only harder. They come in various colors to match different woods. You have essentially two opportunities to use a wax stick: before you apply the final finish and afterward. If you use it before applying the final finish, you need to seal the wood with shellac first. This step isn’t necessary when you use a wax stick after applying the final finish because the finish seals the wood.
To apply a wax stick, simply draw it on by pressing it into the defect with the tip of the wax stick, a putty knife, or your finger and then remove the excess with a putty knife or piece of plastic.
Shellac sticks: Shellac sticks come in tons of colors, look good, and are easy to apply. Shellac is a natural, low-toxic product made from beetle excretions that you melt with a soldering iron and let drip into the surface imperfection. You then press it in with a putty knife or chisel and wait for it to harden. After the shellac is hard, you scrape it flush with a chisel or thin cabinet scraper and then sand it lightly with fine sandpaper.
Glue and sawdust: Using a mixture of wood glue and sawdust to fill a hole or crack in a project allows you to match the wood you’re working with exactly because you use sawdust that created while milling the boards for the project. This low-tech solution requires just the right amount of glue and sawdust to get a filler that’s both durable and stains well (not hard to do — it just takes some experimentation).