to fill in gaps, i have often mixed up my own filler from glue and sawdust. I was never quite satisfied with the result, because the glue residue affected the finish. Now I use the new stainable glues mixed with sawdust. The fine sawdust from my palm sander’s dust collection bag is excellent for mixing.
I also found that rubbing the joint with sawdust gives a slightly rounded and smooth edge that stains well. I store the sawdust in
containers labeled by type of wood.
