Balsa is such a special wood! It's so soft that it is great at "taking" the compound and then conforming to irregular surfaces. I've seen guys use it with compound on gouges and veiners because it is so conformable. It has a variety of unique uses. When they first landed the Apollo spaceships on the Moon, they tested many materials for the actual feet of the craft and they ended up using balsa. I believe it was because it was light and it would crush in a predictably controlled fashion and would conform to the surface thereby contributing to a level landing. If anybody wants to play with some, you can get it at Hobby shops in the modeling section. They usually have a variety pack of different sizes and shapes. I always have a pack on hand as when children come over, I start them off with a Dremel and a hunk of wood and they usually end up with something like a little sailboat they set out on our koi pond. They light up when they find they can do something else with their hands besides push buttons on a video game. Balsa should be in everyone's life.