Ok, you asked for a home formulation, you got it! How useful this is, I can't say...

From Wall & Jordan's Photographic Facts & Formulas:

Black for Cameras - This may be used for wood or leather, inside or out:

Nigrosine, spirit soluble ------------------- 2.5 g
Bismark brown ---------------------------- 0.65 g
Denatured alcohol or methylated spirit - 3.0 ccm
Aniline ------------------------------------- 29 ccm

Heat the dyes with the alcohol until dissolved, and then add the aniline; apply with a brush and dry before the fire or in the sun. Or, for a dead matt varnish, lampblack may be rubbed up with gold size or shellac varnish, using as little of the liquid as possible; then thin down with turpentine.