Some really good input here. I have used the shoe polish method to rejuvenate amplifier Tolex with great results. Never thought about using it on wood.
Plus one on the viinegar and steel wool
Torrefaction is my other favoured method. Wrap in foil bake in a hot oven for 20 minutes.
200 Celsius or 400 f should do it.
I have used the steel wool and vinegar for quite some time on my customers custom picture framing and it works quite well. Sometimes when first applied it almost has a purple tint but then darkens to sometimes dark gray and sometimes to black.
I have also started experimenting with Keda dyes from Ebay. Haven't tried the black yet but the red works well. Looks great on maple, they have a wide range of colors and one can mix them to make custom colors.