#2
A stain for staining ebony or ebonising wood?

If it's the former, and it IS for making it a uniform black, then I would assume that it is just a black stain. However, a lot of woodstains in my experience can be quite thick and flush out detail, as well as not being absorbed particularly well. Since ebony is already almost black, a coating is the last thing you want*, and since ebony is a very hard wood, I expect that a stain for it would have to be thinner than your average softwood stain, just to soak in properly.

If it's the latter, I would expect that it's not completely black, since ebony isn't really completely black.

*You don't want your stain to just coat the outside of the wood because generally in guitars, ebony is used for fretboards and will therefore have strings rubbing on it, and rubbing off any coating it has.

A link could help though.
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