Sssseeewwww ... falls jemand interessiert ist, meine Aniline-Erfahrung.
I purchased a piece of flame maple from 'holzkarle,' from whom I have bought wood in the past and with whom I have had good experience. The piece was 13 mm thick, and slightly large in both of the other dimensions. I took the wood to a Schreiner and had it sanded down to 6.6 mm. I cut out the fretboard riser, dry sanded to 400 grit, moisened the wood with distilled water to raise the grain, and after drying sanded it smooth again with 400 grit. This is seen in the first photo. You can clearly see the flame, but it is not particularly intense.
I mixed a brown dye. I used water-based dyes, which work well with maple. If I had used other woods (mahogany, alder, ash ...) I would have needed an alcohol-based dye. Water-based dyes can be used in woods which need little or no filling, which as far as guitars is concerned limits them to maple. The dye is a powder which is mixed with hot (not boiling) water and allowed 15 minutes to dissolve. I applied it with a clean rag.
First I dyed the wood brown (see photo 2). After drying, I sanded back, which left the 'flame' still dyed, but the 'field' between close to the natural color. Photo 3 shows the result. As you can see, the flame is much more obvious now.
This was followed with several coats of amber dye, letting it dry and sanding (400) after each application. The result is shown in photo 4.
Still to come is the finish coat. I will use KTM Spar Varnish, which is a water-based urethane often used by acoustic guitar luthiers who do not want to destroy their lungs with nitro. It can be brushed on, but requires 6 coats (with sanding) within six hours or so, and buffs to a high luster. I will need a completely free weekend for that, since each coat has to be applied before the previous has cured, or it won't bind, which means I will be completely absorbed for the duration. Once that is finished I can remove the old fretboard, attach the riser, and either reinstall the old fretboard (if it survives the removal) or install a new one.
I bought my dyes in the US. Since they are powder, there is no problem shipping them. I bought a set of 7 colors, which didn't cost much more than buying just the two colors I wanted.
steven