UV Cure Resin Fingerboard Inlays

[Gilmourisgod]

I'm taking another crack at doing the "glitter" type crushed Mica inlays used on deluxe Rickenbacker basses of the 60's-70's. This is more or less what I'm shooting for, minus the yellowing:

So far I've cut the fingerboard recesses to 1/8" deep, which is the recommended maximum for single pours of this type of resin pour, plus I don't want to weaken the board any more than necessary.

From what I've read, they painted the recesses with a light grey pigment and then used some kind of polyester resin pour, but the method changed repeatedly over time, I gather it's a bit of trade secret, and they only do it on limited runs now, so who knows.

I first attempted this about 8 years ago using clear epoxy casting resin with two grades of crushed MOP as the "glitter". The initial pour was water-clear and looked great. I used a digital scale to mix the 1:1 ratio, mixed the hell out of it, etc, and it seemed to cure properly, but after fingerboard radius, sanding, and polish through ALL the micromesh grits, buffing compound, polish, etc, it never returned to water-clear, more of a transluscent. it still looks cool, but not what I was shooting for.

The UV Cure tech has advanced hugely over the last few years, with a lot of the "crafting" crowd adopting it for jewelry and other chatchka. the latest iterations claim to reach a Shore D hardness of 80-85, which is in line with most plastic fingerboard inlays, so it should have a similar level of scratch resistance. I ordered this Kit, , including the UV Cure lamp off Amazon, and in the Interest of Science, will post my results. If it works well, this may be a good solution for custom inlays that would be difficult or nearly impossible to cut out of something like solid MOP sheet stock. There are a couple YT videos of people using it and then machining the fingerboard radius with CNC, so it seems to machine cleanly, and supposedly can be polished up to a high gloss.

https://www.amazon.com/JDiction-Resin-Upgrade-Resistant-DIY/dp/B09N6LNH3Q/ref=sr_1_1_sspa?crid=4DW4NB7AOCKR&dib=eyJ2IjoiMSJ9.-AQhS9AStMVkIZUHjUA3nsS6d3yq-q_02e2-hzjxO4Da0jWLDTR46d7-NiIh25LTMmqbyPug-iSZspqlKYluoN8QrJcuM0n4OcExTu8qbXuoUQucYRMfUXSBhzQBC1C4FhABIjnb5rZV1qflx8qA3e2o_-_u3ay0-64ylsNtlWljxj4DljK6JKMfPGvx4LjjvdF6ZtUswtGIA1XbygXRZ2IhblNXXVnXRrI6tqTq4zvN7FLJRupxH-R-1U0BLTufZj9pez6OxbqCLnfLit8upmvYbNfC05J_xgxL6gb4Hxg.dfg6hoWc1BbdpIEzarMHcIhbAu2WOG8WV0CEtfh3GEk&dib_tag=se&keywords=jdiction%2Buv%2Bresin%2Bwith%2Buv%2Blight&qid=1767805771&sprefix=%2Caps%2C128&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

Has anyone else tried something similar? Any tips or advice appreciated.

 

[Beej]

I wonder if you could make a sheet of it and then cut it to size? If you ran into any curing issues, clarity problems, etc. you could always ditch it and make a new sheet.

One thing I've noticed from my daughter's jewelry-making, is that if there is something opaque inside the resin, it will block the UV from reaching it to cure. So when she's make pendants, they have to be cured from the top and after hardening, cured from the bottom too, just to make sure the UV hits all areas. This could be something that affects how the JDiction resin cures. JDiction does seem better rated than the "Yieho" stuff that I have, though I've not had any problems with it.

 

[Gilmourisgod]

My current plan is to coat the interior of a test recess on scrap with a thin mix of UV resin and mica powder mixed into it to cover the red/brown of the Bubinga. If it's still too transparent, I'll have to add a bit of white or grey pigment. Hopefully this will still cure as it will be very thin. If that looks good, and cures properly, I'll add a layer of larger mica flakes and submerge them in untinted UV resin. Obviously no way to get UV to both sides of a transparent mold, so hoping this works one- sided. The sheet stock idea is interesting, but I'd have to cut them perfectly to size, which is harder that it sounds based on personal experience.

 

[Beej]

Cutting inlays can be a pain, but when I'm making them, I usually cut large and then machine-sand them to the line.

 

[Gilmourisgod]

Thought of another option: paint the recesses with tinted 2-part epoxy resin with a small amount of tint in it, and then when it's cured, overcoat with the UV resin just straight clear. Apparently that should work if I rough sand the epoxy slightly. That would seem to cater to the best properties of both materials, and opaque epoxy still cures just fine chemically.

 

[Dirk Diggler]

Oh man I've got nothing to add other than my old '69 4001 used to have such great clear 3d sparkle. Well of course they yellowed over the years but held mostly clear.

I also love seeing your Ric inspired creations.

What they were doing back then was indeed magical, I can understand them holding the secrets, it's a good trick.

I see what you mean about the previous attempt looks more like satin almost, which is interesting, but I get what you're shooting for.

Have you checked into the West System Epoxy stuff as an option?

The UV thing makes sense since it's really only the surface layer you're polishing up.

Good luck man, you are indeed a brave person!

 

[boxerrider]

The Ric has a gloss finish over the whole board. I can see how glossy inlays next to matte/unfinished wood could be tough to pull off.
May the Force be with you!

 

[Gilmourisgod]

I've used West System on a bunch of stuff over the years, but IME it's too prone to bubbles and yellowing. I tried it on a few mockups the first time and couldn't get water clear results out of it. This tech is changing quick, the UV clearcoat seems more promising at the moment. I'm sure the thick laquer fretboard coating Ric used added to the gloss, but it also makes it impossible to crown the frets, which is why Ric fret tops are essentially flat.

 

[Jazzdogg]

I'm taking another crack at doing the "glitter" type crushed Mica inlays used on deluxe Rickenbacker basses of the 60's-70's. This is more or less what I'm shooting for, minus the yellowing:

So far I've cut the fingerboard recesses to 1/8" deep, which is the recommended maximum for single pours of this type of resin pour, plus I don't want to weaken the board any more than necessary.

From what I've read, they painted the recesses with a light grey pigment and then used some kind of polyester resin pour, but the method changed repeatedly over time, I gather it's a bit of trade secret, and they only do it on limited runs now, so who knows.

I first attempted this about 8 years ago using clear epoxy casting resin with two grades of crushed MOP as the "glitter". The initial pour was water-clear and looked great. I used a digital scale to mix the 1:1 ratio, mixed the hell out of it, etc, and it seemed to cure properly, but after fingerboard radius, sanding, and polish through ALL the micromesh grits, buffing compound, polish, etc, it never returned to water-clear, more of a transluscent. it still looks cool, but not what I was shooting for.

The UV Cure tech has advanced hugely over the last few years, with a lot of the "crafting" crowd adopting it for jewelry and other chatchka. the latest iterations claim to reach a Shore D hardness of 80-85, which is in line with most plastic fingerboard inlays, so it should have a similar level of scratch resistance. I ordered this Kit, , including the UV Cure lamp off Amazon, and in the Interest of Science, will post my results. If it works well, this may be a good solution for custom inlays that would be difficult or nearly impossible to cut out of something like solid MOP sheet stock. There are a couple YT videos of people using it and then machining the fingerboard radius with CNC, so it seems to machine cleanly, and supposedly can be polished up to a high gloss.

https://www.amazon.com/JDiction-Resin-Upgrade-Resistant-DIY/dp/B09N6LNH3Q/ref=sr_1_1_sspa?crid=4DW4NB7AOCKR&dib=eyJ2IjoiMSJ9.-AQhS9AStMVkIZUHjUA3nsS6d3yq-q_02e2-hzjxO4Da0jWLDTR46d7-NiIh25LTMmqbyPug-iSZspqlKYluoN8QrJcuM0n4OcExTu8qbXuoUQucYRMfUXSBhzQBC1C4FhABIjnb5rZV1qflx8qA3e2o_-_u3ay0-64ylsNtlWljxj4DljK6JKMfPGvx4LjjvdF6ZtUswtGIA1XbygXRZ2IhblNXXVnXRrI6tqTq4zvN7FLJRupxH-R-1U0BLTufZj9pez6OxbqCLnfLit8upmvYbNfC05J_xgxL6gb4Hxg.dfg6hoWc1BbdpIEzarMHcIhbAu2WOG8WV0CEtfh3GEk&dib_tag=se&keywords=jdiction%2Buv%2Bresin%2Bwith%2Buv%2Blight&qid=1767805771&sprefix=%2Caps%2C128&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

Has anyone else tried something similar? Any tips or advice appreciated.

Have you considered applying a second coat of UV-cured finish after the fingerboard has been radiused and sanded smooth?

I ALWAYS recommend experimenting using test pieces until totally satisfied with the results.

Good luck!

 

[Engle]

Very cool! I've got nothing to add, but will be watching this thread to see how it goes!

 

[joe vegas]

Labor of Love. Outstanding!

 

[BassUrges]

My experience with UV cure resin several years ago was that applying it to wood inhibited curing. Considering I bought it at Woodcraft that seemed like a flaw.

Smooth-On has some non-yellowing epoxies that I have used with success. They are my source for any rubber or plastic. I have not had the translucency problem so I wonder if the MOP had something to do with it. Here is a bowl that was turned and sanded and polished back to water clear.

 

[CrunchyFrog]

If my memory is still what I hope it is, I recall John Hall posting in a forum and stating that the original colourful, sparkly inlay material was from a (Japanese?) manufacturer of drum wraps. If someone can confirm this, please do.

 

[Gilmourisgod]

I've read that too, but from the first photo I posted, it's pretty clearly mica flakes, so they used a few different materials over time, including some sparkly sheet stock similar to Abalam, that may be what John Hall was describing. I can see how any UV resin that soaks into wood wouldn't cure, which is why it may be better to to seal the recesses with a light grey tinted epoxy resin first, and then fill the rest with UV resin. I did a lot of research on epoxy resins, unfortunately most of the "tabletop" variety come only in quarts or even gallons, which makes for an expensive experiment. I'll post the whole sordid process here, fingers crossed!

 

[Matt Liebenau]

If all you want to do is seal the inlay routes before the pearl and resin layers you should be able to do that with shellac or a polyurethane brushed or sprayed in. Test for compatibility first obviously.

 

[Dirk Diggler]

Crunchy Frog has an excellent thought.

I just searched, check this out:
Drum wraps - Precision Drum Company, Inc. - Since 1961

p.s. Bass Urges your turned bowl looks awesome!

 

[Gilmourisgod]

If all you want to do is seal the inlay routes before the pearl and resin layers you should be able to do that with shellac or a polyurethane brushed or sprayed in. Test for compatibility first obviously.

What I did on the first one was to paint the recesses with a thin layer of white-tinted epoxy, and dusted the wet epoxy with super-fine crushed MOP, which served to both seal and cover the bubinga so it didn't show through. Then I put a thin layer of the the larger MOP flakes in at the just the bottom of the recess and flooded the whole cavity with clear epoxy. I used an epoxy called Envirotex-Lite, which is supposed to be super-hard, a lot of pedal builders use it for floor stompers. The mystery was why it poured and cured water-clear, but could not be polished back to clear once radiused and sanded, regardless of how high a grit I used, up to an including hand-polishing it. One possibility is that I used a small amount of acrylic paint as the pigment in the epoxy instead of some kind of alcohol or polyester based pigment. I've since read that can cause resin to go slightly cloudy. Science! I was kinda hoping somebody else had done this before and would swoop in, like Batman, with the exact process but... Nope. Gonna be a bit trial and error, on bubinga scrap, of course. I won't touch my actual board until I get this right.

 

[Bruce Johnson]

What I did on the first one was to paint the recesses with a thin layer of white-tinted epoxy, and dusted the wet epoxy with super-fine crushed MOP, which served to both seal and cover the bubinga so it didn't show through. Then I put a thin layer of the the larger MOP flakes in at the just the bottom of the recess and flooded the whole cavity with clear epoxy. I used an epoxy called Envirotex-Lite, which is supposed to be super-hard, a lot of pedal builders use it for floor stompers. The mystery was why it poured and cured water-clear, but could not be polished back to clear once radiused and sanded, regardless of how high a grit I used, up to an including hand-polishing it. One possibility is that I used a small amount of acrylic paint as the pigment in the epoxy instead of some kind of alcohol or polyester based pigment. I've since read that can cause resin to go slightly cloudy. Science! I was kinda hoping somebody else had done this before and would swoop in, like Batman, with the exact process but... Nope. Gonna be a bit trial and error, on bubinga scrap, of course. I won't touch my actual board until I get this right.

I suspect the reason why the epoxy wouldn't sand and polish back up to clear was that you were embedding material from the sandpaper into the surface. Fine abrasive particles and the chemical from the Stearating process got smashed down into the epoxy by the heat and pressure of sanding. This is a common problem when trying to polish up clear Acrylic, using sandpaper. The debris from the sandpaper is filling the fine scratches and making the surface smooth, but it's cloudy, not clear.

The solution is......to not use sandpaper. Use mechanical cutting edges to trim and smooth the surface. Use a big fine sharp file to radius the surface of the inlay flush with the fingerboard. Then drag a sharp scraper over it to take out the file marks. Files and scrapers peel material off without embedding debris.

From there, go straight to buffing. I recommend a soft cotton wheel with a plastic polishing compound. They make special buffing compounds just for polishing plastics, like acrylics and epoxy.

 

[Gilmourisgod]

I suspect the reason why the epoxy wouldn't sand and polish back up to clear was that you were embedding material from the sandpaper into the surface. Fine abrasive particles and the chemical from the Stearating process got smashed down into the epoxy by the heat and pressure of sanding. This is a common problem when trying to polish up clear Acrylic, using sandpaper. The debris from the sandpaper is filling the fine scratches and making the surface smooth, but it's cloudy, not clear.

The solution is......to not use sandpaper. Use mechanical cutting edges to trim and smooth the surface. Use a big fine sharp file to radius the surface of the inlay flush with the fingerboard. Then drag a sharp scraper over it to take out the file marks. Files and scrapers peel material off without embedding debris.

From there, go straight to buffing. I recommend a soft cotton wheel with a plastic polishing compound. They make special buffing compounds just for polishing plastics, like acrylics and epoxy.

That sounds like it could have been my problem! The rub is the that I can't pour epoxy or resin into a pre-radiused board, I'll be pouring it while flat so it can self-level, and then radiusing it afterwards in my new jig. I have a good quality Freud 1" dia. flattening bit, so the cured resin will get it's initial shape via machine cutting, and it should be dead-flush with the radiused wood board. 'll try the scraper method after that on one of my samples. I have no previous experience with the UV resin, but everything I'm reading online from the "Crafter" community is that they do polish UV resin with stuff like micro-mesh, and seem to get good results. I'll try various methods and see what works. I have a Novus plastic polish kit left from a failed attempt to to polish a Boston Whaler windscreen, so I'll break that out too.

 

[BassUrges]

Micro mesh is great stuff. I have used it on wood, acrylic, epoxy, CA, shellac, and 2-part clear automotive poly with good results every time.

I also have a supply of silicon carbide wet/dry in grits up to 6000 meant for auto body work. I have lubricated with water, alcohol, and naphtha, depending on the surface. I'd avoid anything sterated at all, ever, for any purpose. Maybe it works for furniture you plan to paint with latex but I would never use it for nice pieces.