Wood floor filler is a product used to fill all the cracks, nooks, and crannies on the floor. Filling a floor helps to make it look more complete. Wood floor filler is often used in cracks, end joints, and knots. The filler dries in as little as 20-30 minutes and is both sustainable and sandable after drying. Unfortunately, some wood species do not have a filler color specifically formulated to match their unique color. When working with a material that does not have its own shade of filler, you may need to fix together premixed fillers or use a product like wood doe. In addition, wood filler is not created to be elastic, and movement will cause the filler to crack.