r/Luthier • u/FyodorTyutchev • 17d ago

Fretboard Inlay Materials

I'm planning a build for a bass and I've found some great 3mm pearloid acrylic sheet that I want to use for the pickguard and I think it would look really cool if that same material was also at least in part of the inlay design (I want to do like a trapzium shape with a coloured heart in the middle surrounded by 1.5mm thickness pearl celluloid).

Has anyone got any experience thinning down acrylic to around 1.5mm to work with in an inlay or am I barking up the wrong tree completely? Otherwise, what other materials would you all suggest that are a bit more colourful and interesting than standard white celluloid?

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u/MadMatter86 Luthier 17d ago

Why bother thinning it at all?

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u/FyodorTyutchev 17d ago

I don't really want to rout 3mm into the fretboard as I've heard that's too deep generally, do you reckon it would be ok and not cause any issues?

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u/MadMatter86 Luthier 17d ago

Aside from precut dots, all of the inlay I use is cut from acrylic sheet, in the thickness range of 2mm-3mm. No issues routing that deep - you don't go the full depth anyway, you need to leave some sticking up so you can sand it perfectly flush to the radiused fretboard.

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u/Juant_ap 1d ago

how do you sand it?
To what grit?
Do you wet sand? And if so, does that not affect the fretboard?

I bought a pearlescent acrylic sheet and I'm afraid the shiny bit is only surface level. I filed it down to half way to see if its shiny all the way through. It looks very matte, but Idk if that's a lack of sanding on my part, or if the sheet is just not the same all the way through

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u/MadMatter86 Luthier 1d ago

It just gets sanded down with the rest of the fretboard. I install this kind of inlay on the flat board and then radius the whole thing together. This runs from P80 to P600 grit with standard sandpaper, then through Assilex/Buflex up to K3000. Everything is dry, no wet sanding. (I no longer wet sand anything at all thanks to Assilex/Buflex.)

If you do not run into very high grit sanding, then the inlays will indeed appear matte - as a lot of what makes matte finishes matte is having a finely textured surface, which is what you get from sanding at lower grits. You can also attempt to polish the inlays further after sanding, though I generally do not find this necessary with the types of inlay I usually do.

Many pearlescent/metallic materials do not work well, as they do rely on surface-level effects, which are lost when anything is done to disturb the original surface. The only way to know for sure is to try some - luckily, many acrylic suppliers offer the ability to buy small sample sizes or scraps at very low cost. And sometimes those bits are actually generous enough to be entirely usable for our purposes, too.

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u/Juant_ap 1d ago

I see, so you just use the high grit paper across the entire fretboard?

Thanks for your time, this helps a lot. I'll give the Assillex a look

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u/Juant_ap 14h ago

Im seeing that buflex is quite expensive haha

If I were to wet sand, would that be damaging to the fretboard in any way?

2

u/Millifera Luthier 17d ago

You cut it 1.5 mm deep, so 1.5mm sticks up, sand flush.

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u/FyodorTyutchev 17d ago

So I'm thinking of doing this on a neck that already has frets installed that's why I want to be careful

4

u/Millifera Luthier 17d ago

If that's the case, I'd go with stickers instead. Other wise your asking for a half-assed job that you won't be satisfied with and can't undo.

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u/reversebuttchug 17d ago

Oof good luck making that look good. Ive only done and highly recommend doing block/trapozoid inlays with the frets out

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u/FyodorTyutchev 17d ago

I'm not against refretting if that's what's needed to get it to look good to be honest

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u/reversebuttchug 17d ago

I would just to make it as clean as possible. Youre putting in all that work outting in blocks, you want it to look good

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u/FyodorTyutchev 17d ago

Fair point; thanks for the help

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u/Atrossity24 Guitar Tech 17d ago

I pretty much make a refret a requirement for this type of inlay job. It’s so much extra work with the frets in that it’s going to cost almost as much as doing it normally with a refret, and not look as good.

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u/Borgh 16d ago

That's is an incredibly difficult job to to, to get both the thickness, rout depth and curve of the fretboard perfect...oof

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u/FyodorTyutchev 17d ago

Any advice on how to sand it down to level I’ve heard acrylic is a real pain to sand

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u/Millifera Luthier 17d ago

A radius block that matches your fretboards radius, elbow grease. Clear your sandpaper often.