Epoxy as clear coat finish over stain?

[Rabbit]

The downside to suction brushes is you need to run higher pressure than a gravity fed brush. Professionally you find that in general, airbrush artists working of hard surfaces use mainly gravity fed brushes, and those working on fabric or canvas mostly gravity fed. The Airbrush artist Mike Lavalee had Iwata make him a 0.3mm brush with a larger cup for less refills doing large surfaces for his true fire. If you are also planning to use an airbrush on your boards and you are selling them, do not get a cheap brush... once you have felt the performance difference of something like an iwata or richpen, you won't want to go back.

[JimC]

I'm something of an epoxy fan, used it a lot for boat building. Not much for my amateur level luthiery though.

There are ultra thin paint on epoxies, and I've used one to stabilise lower quality engineered rosewood fingerboards.

Whilst UV resistance is a huge concern for coatings that live out in the sun, I don't think I'd be particularly worried about guitars that normally live indoors and in cases/bags.

For whatever my opinion is worth though I don't think I'm very enthusiastic about epoxy as a body finish material: I'm a great believer that you should play to a material's strengths, and really decorative clear coating isn't an epoxy strength, unless you're using it to cover an underlying epoxy laminate. So if its a carbon fibre body fine, but I reckon there are better alternatives for wood. I suppose stabilising a really spectacularly unstable spalted or burled finish might be one possibility, but really that's playing to the strength of low shrinkage gap filling adhesive properties.

Jim C

[RocknRolf]

I'm something of an epoxy fan, used it a lot for boat building. Not much for my amateur level luthiery though.

There are ultra thin paint on epoxies, and I've used one to stabilise lower quality engineered rosewood fingerboards.

Whilst UV resistance is a huge concern for coatings that live out in the sun, I don't think I'd be particularly worried about guitars that normally live indoors and in cases/bags.

For whatever my opinion is worth though I don't think I'm very enthusiastic about epoxy as a body finish material: I'm a great believer that you should play to a material's strengths, and really decorative clear coating isn't an epoxy strength, unless you're using it to cover an underlying epoxy laminate. So if its a carbon fibre body fine, but I reckon there are better alternatives for wood. I suppose stabilising a really spectacularly unstable spalted or burled finish might be one possibility, but really that's playing to the strength of low shrinkage gap filling adhesive properties.

Jim C

Thanks Jim, I think you worded it perfectly. After going over all the comments and actually working with epoxy today I realised this too.
There is a lot that can go wrong with epoxy as a top coat and though it is all fixable, I would end up using epoxy just because I already have it and know how to work it. A pretty weak argument if you ask me, also there are far easier products to work with.

So I'm going to do a bit more reading into poly as I think this has the highest chance of a durable finish that doesn't discolour the underlying colours.

[Rabbit]

So I'm going to do a bit more reading into poly as I think this has the highest chance of a durable finish that doesn't discolour the underlying colours.

Hehe just make sure it's poly urethane and not poly ester!

[Simon Barden]

Though Fender have used a clear polyester coat over the body as first sealing coat since 1963 (except for all-nitro pre-63 reproductions, custom jobs and some special editions). Clear, and goes over any initial staining applied. UV cured, it sets hard in 15 minutes and is paintable within an hour. It stops any finishes from sinking into the wood and saved them hours in paint and prep work. They've then put nitro or polyurethane or even more polyester over the top of that.

[RocknRolf]

Hehe just make sure it's poly urethane and not poly ester!

Just when you think you have said something funny or outrageous, Simon is on standby to normalise- and flavour it with some history haha

[Simon Barden]

I must admit that I can't but think of thick hard plastic vibration-dulling finishes when I hear the name polyester (as well as some really nasty shirts in the 70s).

[McCreed]

Polyester finish is used more widely than you might think, and TTBOMK, polyester is more or less a variant of polyurethane.

It's also worth pointing out that the "poly" that we DIY'ers are buying at the hardware store is very different to what the guitar factories are applying.

[JimC]

TTBOMK, polyester is more or less variant of polyurethane.

I think you have to me using a *very* wide definition of the word variant for that to be true, they really are rather different, although I suppose there's an argument that one thin coat of polymerised plastic can't be utterly different from another.

[Rodc]

@Rodc - Like anything, you can spend as little or as much as you want. There are mini compressors and airbrushes that cost more than my big compressor and guns, but for a starting reference this compressor ticks a lot of boxes:

Artlogic AC1418

As for airbrushes, that's harder to specify because there are a number of different types, and depend on personal preference.
Such as single or dual action, gravity or suction and nozzle size (some brushes accept various size needles & nozzles, other just one).
You can a cheap $40 off-brand* one from eBay (like me ) or you can get a $400 Iwata.

My brush is a dual-action with .2/.3/.5mm needles & nozzles, and will do both gravity and suction feed. I have only ever used the .5 nozzle since I have only used it for applying poly.
As far as I can tell, mine is a knock-off of a Sparmax. The biggest issue I've found with the no-name one is spare parts like O-rings, but performance-wise, it's worked great.
I have bought generic O-ring kits that provided the ones I needed, but also gave me ones that don't fit my brush so are of no use. If I had a genuine Sparmax or Iwata I could get full O-ring kits that would purpose fitted.

FWIW the reason I cheaped out on the $40 one was I knew nothing about airbrushing and wasn't sure what results I would get so I minimised my outlay in case it was crap! I would spend more knowing what I know now but I haven't upgraded the airbrush because I bought a mini touch-up gun instead.

*I just checked, and mine branded "Voilamart"

Thank you again for the great info McCreed!