A while ago I bought a molding brush from an antique dealer. It is one of those carpenter brushes with a molding at the base and a blade in the same shape as the molding. These woodworking brushes are usually not in very good condition, so I thought it would be worth nothing more than to decorate.
The fact is that one day in a hardware store I found a gouge sharpening stone (a multi-shaped sharpening stone) and I thought that with the shapes that stone had I could try sharpening the molding brush blade.
What I did was remove the blade (the iron) and I cleaned the oxide with a sandpaper. And then, with a little patience, I sharpened the blade, taking advantage of the shapes that these sharpening stones have. Little by little, adapting the different curved areas of the stone to the curved areas of the blade molding, and doing the same with the flat areas of the whetstone and the flat areas of the blade, I managed to sharpen enough to To think that he still managed to get some shavings with this old brush.
With a table well held vertically in the vice I put the brush on the edge of the board resting the side projection of the brush against the edge of the board, and began to brush. I had to push the brush decisively, and at first the chips would get stuck in the brush, but little by little the molding on the edge of the board was revealed. And if you have worked with carpenter brushes, you will know that you can get a finish on the wood that is not achieved no matter how much we use the sandpaper.
Now I have other old wooden brushes, and maybe I will be encouraged to sharpen them and try them out, but I don't know if I will dare to do a complete project with them.
At least now I know I can sharpen them, although I will need a little patience. The same as when I need sharpen chisels with the sharpening guide. If we try to sharpen in a hurry, we may not get a sharp enough cutting edge.