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Epoxy - flat using a turner (rotisserie-like)

#21
warx said:
I did not know auto clearcoat would stick to wood. That might be more do-able by taking the neck to a body shop and having them spray it next time they're doing clearcoat rather than me kitting up for it.
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That's what I recommend for you. I messed around with epoxy coating fingerboards for a while, and gave up in frustration. Way too much work and not worth it overall. A good hard automotive poly clearcoat on the fingerboard is simpler and better, in my opinion. I don't get why people still want to use epoxy. And if you aren't set up to spray 2-part poly finishes, go to your local auto body shop. Have your fingerboard nicely trued up, sanded and masked. They'll spray on a couple of light (to them) coats, and you do the rest.
 
#22
Well I've got my epoxy already so I'll keep going and see. I just brushed on the first coat of MirrorCoat. Besides a couple of dimples that won't go away with brushing etc. it seems pretty good! i might only need two coats at this rate. I'll wait 6hrs and brush on another coat.

Also I was going to level my "ski-jump" but tweaking the truss rod to get the neck totally straight and it went away and was pretty flat the whole length. It was actually not at the 12th fret but the 8th or so.
 

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#23
So it's hard to put this stuff (MirrorCoat) on thin enough it does not run. The thinnest a brush would leave it was about 0.010 and it did migrate a bit to the sides and scavenged the center to cause fisheying. So... I'm doing a second coat (also 0.010) but this time with the board inverted. I can see it migrating to the center now. I'm thinking the rotisserie would be effective and evening this out. Too late now of course but I hope I'm balancing it out enough to get a base to sand without too much effort. I can't say this is saving work over dam and fill though...

Next time I will try the auto bodyshop - or buy a $40 gun and $55 2-pack clear-coat.
 
#24
So I've been reading more about 2K (I used to call it 2-pack) polyurethane finishes. I see they even have wood versions available now - most are acrylic based. Not totally sure what typical auto 2k poly is or which is better for fingerboards. I do other woodwork finishing in lacquer or water-based [1K] polyurethane. Really thinking about investing in this. To be able to apply so uniformly that no reshaping is reqd is a big deal.

I still can't tell how the hardness and wear of this finish compares to polyester resin or epoxy. Perhaps I'll have to do some samples and get that CNC driver (or BBQ rotisserie motor) and have it rub a 0.110 E-string on it continuously for a few days.
 
#25
Bruce Johnson said:
I don't get why people still want to use epoxy.
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I see it as a preferable to use the hardest applicable substance, for the purpose of coating a fretless board... because it's not done for aesthetics... rather to enhance or brighten the tone/muah/blossom.

Does not epoxy have a higher compression strength than poly? ... more solids or something ?

I see it as analogous to nut, saddle or fretwire material choices. The density affecting the tone.
Like.... a nice resonate wood board with a few mil layer of polished quartz crystal somehow fused to the surface, would be fantastic.

I use CA ... because I hate epoxy.
It cures up hard/ crisp / brittle even... and polishes up crystal clear & bright.
But... it's a 30 coat, pain in the butt process.

Are the UV cure compounds like SolarRez, much tougher than a 2K poly?
(compression/scratch resistant)
I am wondering how they would compare to epoxy or CA for coating fretless boards.
 
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#26
I tried Solarez on a fingerboard. It seemed hard enough, but it didn't soak into the wood at all. It could be that I polished the fingerboard up too much before applying the Solarez. When I tried to cut off the Solarez that dripped over the edge a corner peeled up, I pulled on it (it was ruined at that point anyway) and the whole board peeled off in one piece.

I use CA as well, I hate the fumes, but it's relatively easy and it's certainly hard.
 
#28
Jisch said:
I tried Solarez on a fingerboard.
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It's interesting that its viscosity can be altered by cooling or heating. Maybe you could pre-shape it on the board with a radius block (and standoff rails - or smear). I'm thinking the ultimate bond strength only has to ensure it stays in place if it gets knocked and perhaps a quick brush of it warmed as a sealcoat followed by a cold smear that you shape. Do you have to invest in all the UV lamps though?
 
#31
I found my posts on the topic - I had to look through a couple build threads (which was a lot of fun!) before finding - post 84 in the Carl Factor thread: Winter 2019 Build Off - The Carl Factor

I exposed the above bass to sunlight on a cold winter day (20F degrees), the stuff kicks after just a few minutes, it's unlikely the temp really did anything to the viscosity of the Solarez in the short amount of time it was outside.

Also I recall a user named "Alder" tried using it and had equally disappointing results - I didn't search through his thread, it's massive.
 
#34
Jisch said:
Yes, i used polyester resin.
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TBH my general impression of polyester resin is that it would do this. The only way I've got it to stick even half-decently to wood (marine ply roughed at 80-120grit, 18oz cloth) was with vacuum bagging. I switched to epoxy when anything required real attachment.
I wonder about vinyl-ester though. To me that really just meant polyester resin with more heat and chemical resistance. SolarEZ is saying it has much more adhesion.

Anyways, I have my three brushed coats (estimating 10 mil each) on and each sagged in whatever direction was downwards. Basically, I've saved myself only a little bit of sanding over doing the dam and pour.

Here's a pic of the migrated/scavenged first coat after three hours of excruciatingly slow MirrorCoat curing. Compare it to the pic I posted after one hour where it looked the Money!
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And here's a shot after doing the second coat inverted and third coat upright again but this time adding a dam to limit the sag and just get enough epoxy depth on there for a good sanding. BTW I will sand with a 24" straight edge for the most part and use the radius block every so often to round off the three edges.
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#37
Just to wrap up. The sanding went pretty fast. I only used one sheet each of 120, 220, 400, 800 and 1500. Took 15 mins to get it flat with my 24" file system (Thanks @Bruce Johnson for telling me to file with straight edge following stringline for the majority of the work). I used the radius every so often to keep things in check. 10 mins of sanding with the finer grades. I can't be bothered with glass-like gloss so stopped with just a few minutes of polishing with auto paint scratch compound.

The hardest part was epoxying around the nut slot. I taped it off but it left a little too much uncoated - not sure the best way to handle that. Second worst part was I followed some advice (on TB) to use packing tape not masking tape. Urgh - awful job to remove the sticky gunk (IsoP -> Acetone -> Oops).

Anyways, my nut slots are still too high (why I think this was actually a converted not factory fretless - unless Fender MIM fretless come with a ridiculous first fret height). I had to make my own E (now a D with extension) string nut and tried to it with a micro round file - not great. I just ordered the nut file set from StewMac so will need to wait for that for a true setup.

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