Dennis in Southern Oregon
I am with Tom on this. I have had good luck fuming small pieces using household ammonia. I use a 5 gal paint bucket with lid with a jury-rigged stand on the bottom to hold the pieces above the half cup or so of ammonia. One to three days works, depending on the shade darkening wanted. I was particularly pleased with the results for cherry.
A few years ago I gave a demo at my club on this subject and, in preparation, fumed samples of 16 different species of wood. For each wood, I sanded a small sample and cut it in half, saving one half for comparison to the fumed version. The following pictures, which were included in my demo handouts, show the results. I can’t remember the fume time, but I think it was two or three days. The photography is poor, unfortunately, as I did not go to much trouble, knowing that the club members could see the results directly. Interestingly, all of the woods tried darkened to some extent and many could be said to produce an attractive result.