Nitro finish over acrylic paint?

Axelorox

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I am having a guitar built from parts. I will have some custom artwork done on the body and neck. The artist uses an acrylic primer and acrylic paint. She usually sends them off to be finished in polyurethane before returning to the customer but I am generally not a fan of polyurethane finishes. Would a nitro finish be compatible over the acrylic primer and paint?
 

LtDave32

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It will be fine.

What does not get along are lacquer and enamel.
 

redking

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Dave is the expert, but i will also add that I once sprayed a strat body with an acrylic lacquer and then covered it with a nitro clear coat and that combination was just fine - however the error I made was that my primer was enamel and the acrylic lacquer (the color coat) did not bond with the primer and it chipped off in multiple places.
 

LtDave32

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my primer was enamel and the acrylic lacquer (the color coat) did not bond with the primer and it chipped off in multiple places.
Enamel and lacquer are a disaster when they meet.

Everybody should remember this.

Sometimes, It's attractive to get various undercoatings, sandable sealers and primers at auto-parts stores.

Most of that stuff is for working with modern polys. If you've got a penchant for using nitro (as so many of us do, because it looks so damn nice), be sure what you're spraying under it is in fact compatible with nitrocellulose lacquer.

Don't ask the Trak Auto or O'Reilly counterman. They don't know shit about what we do. Trust me, they don't know. All you're going to get is an unsteady " ummm.. well yeah, sure.. " -And they will be wrong, and your finish will be fucked off.

Howevs..

Lot's of fellas shoot poly down first, then nitro over that. That's fine. Done it myself on special request.

Nitro has a particular "glow" that other finishes come close to, but don't really hit that mark.

-My opinion. It's what I work with on hundreds of finishes. Please, let's not start a poly/nitro war.

If one wants to love poly, then power to you. Love your poly. If one wants to love nitro lacquer, then by all means, love it up.

BTW, pre-catalyzed acrylic lacquer has some merit, if you do not want the finish to yellow. It works like that.

I went to two years of auto-body community college classes while I was still in 11th and 12th grade. Special program they had. This was 1975-1976. This was when lacquer was just being totally phased out of the auto industry, but still being taught. acrylic enamel was the big finish. Remember Earl Sheib? '$29.95.. Riiiiiggggghht". this was his exclusive "Diamond Gloss" paint, and it was synthetic enamel. I was taught this stuff in class. It was almost impossible to paint over a Sheib job, because of the "Diamond Gloss" shit. but lacquer was still regarded as the finest in appearance, right ahead of acrylic enamel.

I was taught leading in with a lead paddle and torch, I was taught bondo. I was taught lacquer, enamel, and the brand-new "emron" coming into the fore.

Nowadays in the auto industry, it's a whole new ball game. Lacquer is not used. It's all catalyzed polys.
 

Brazilnut

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LT is so right.

Actually, I have used OneShot lettering enamel, a synthetic base enamel, to tint lacquer before I shot it. It works. But I don't recommend it, the whole job can go straight to hell if you're not careful. Or even if you are.

I have had nitro fisheye over urethane, but that might have been because of silicone fisheye eliminator in the poly, or maybe I didn't scuff it up enough before I shot the nitro.

I did not know that lacquer would stick to two-stage catalyzed auto paint.
 

LtDave32

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LT is so right.

Actually, I have used OneShot lettering enamel, a synthetic base enamel, to tint lacquer before I shot it. It works. But I don't recommend it, the whole job can go straight to hell if you're not careful. Or even if you are.

I have had nitro fisheye over urethane, but that might have been because of silicone fisheye eliminator in the poly, or maybe I didn't scuff it up enough before I shot the nitro.

I did not know that lacquer would stick to two-stage catalyzed auto paint.

The only way we could shoot over a Sheib "Diamond Gloss" job was with the addition of FEE, or Fish Eye Eliminator. Also called "smoothie".
 

LtDave32

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LT is so right.

Actually, I have used OneShot lettering enamel, a synthetic base enamel, to tint lacquer before I shot it. It works. But I don't recommend it, the whole job can go straight to hell if you're not careful. Or even if you are.

I have had nitro fisheye over urethane, but that might have been because of silicone fisheye eliminator in the poly, or maybe I didn't scuff it up enough before I shot the nitro.

I did not know that lacquer would stick to two-stage catalyzed auto paint.

Lacquer is solids suspended in solvents. When the solvents evaporate, they leave the solids behind.

With enamel, it is not compatible with this process. The solids will crinkle up during the evaporative process.
 

cmjohnson

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I think Dave got it all covered. He's right, and that's that.

I've shot less nitro lacquer than anything else of the three finishes I have worked in for guitars. (Acrylic lacquer, nitro lacquer, and automotive acrylic urethane) Although it's by far more labor to shoot nitro, because it builds so thin and requires so many more coats to build a specific finish thickness, it's also a true pleasure to work with when everything is just right. Humidity low enough that blushing isn't an issue, paint viscosity just right, gun setup just right. When the stars align, you wonder why you'd ever want to use any other kind of finish. The way it sprays, sands, and buffs is simply the best.

I found acrylic lacquer to be the hardest of them to work with. It does have the benefit of building very fast so only a few coats are required, but I had the most trouble getting a good gloss right out of the gun.

I reshot my entire 1978 Cadillac Fleetwood Brougham in acrylic lacquer. (DuPont, paint code 45178L Columbia (Pastel) Blue) That's a HUGE car. And I had to wet sand and buff EVERY square inch of it! It took DAYS. But it sure came out nice after all that work.

Mostly I shoot DuPont acrylic urethane. I shoot it very thin, so thin it competes with nitro lacquer for a thin finish, and I can get it to shoot like glass right out of the gun. The drawback is that to get this thin finish, sanding through to a lower coat is pretty easy and it leaves witness lines between coats that are hard to get rid of. And touchups are harder. And if you should get the finish TOO thick, it may take years but eventually it'll let you know because the affected area will delaminate itself and just literally crack right off the surface below! I've had it happen!

Nitro is easy. Nitro is fun. Nitro looks great. Nitro is forgiving. But it does take time to lay down a good finish thickness. And it will yellow, crack, and check in time. Nitro is definitely what I recommend to MOST people who want to paint a guitar and want a professional looking finish. Even then it will take patience and practice.

I avoid painting in blue with nitro because of the yellowing. For a blue finish I use non-yellowing acrylic urethane exclusively. I don't want it turning green.
 

fatdaddypreacher

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one of the great things about this forum...especially here in the LC. ask what may appear to be a quick question, and i walk away learning something. most threads turn into mini tutorials. I love it. much wisdom here and it's well monitored.
 

LtDave32

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I found acrylic lacquer to be the hardest of them to work with. It does have the benefit of building very fast so only a few coats are required, but I had the most trouble getting a good gloss right out of the gun.
my biggest trouble with acrylic lacquer was sanding out the orage peel. man, that was tough.

But it did buff out flawlessly.. That was that "Harleqin" B&W Michael Shenker flying V. It would not do for that paint scheme to yellow, so a pre-cat acrylic lacquer was used. I still have more than a half-gallon, but being pre-catalyzed, I don't know the shelf life.
Nitro is easy. Nitro is fun. Nitro looks great. Nitro is forgiving. But it does take time to lay down a good finish thickness.
That it does, sir. That it does. Half my build time is dealing with the nitro.

But it's what my customer base wants. So I got to know it like the back of my hand.
 

Brazilnut

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It takes two weeks to do a proper nitro job. But it's worth it.
I used Smoothy , FEE, in my One Shot for years to pinstripe. It eventually contaminates everything in the shop, so I finally quit using it altogether.
You can use nitro over blue. They make a clear, non-yellowing formulation.
 

dickjonesify

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I avoid painting in blue with nitro because of the yellowing. For a blue finish I use non-yellowing acrylic urethane exclusively. I don't want it turning green.
Yeah but, sometimes that greenish color is just perrrrrrfect.

Exhibit A:

AM-JKLUqw7IMOk3rXjwv36EokwfnxC2GIYQFEK2j9tumbJW-UU_Dp6r7cTf62R0xLxUhZm1pqEEx_voeo7e2dX8xugCaYOYWymTszNQJhvQ3iG3uQ13FKNpaLEk2CEAbxMTIo854pStPJIaZIiKs4SiRMupn=w1170-h780-no

And B:

AM-JKLWbhlbKf4T5HaFD3lf1Nh0IaNZKF989FU5Lw4uVcKuDvXc6BK5deesV9F3ctYBIa82lNP9QdTmLlhUBvsXEFovePmDrCpbuTarrG9nfOJ2whqAJ7j-oI5rbZEFUu7Y_UZB2e-Z7yC-FQL-4FhtV8kAt=w1170-h780-no


:dude:
 

cmjohnson

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Clearly that yellowing of the finish works for some people. Personally, when I dye the top and/or apply the color coat to a guitar, that is the color I want it to still be a hundred years from now. If I want a blue-green finish or yellowed white, I'll apply it during painting.

I've seen some pretty finishes turn very ugly due to finish yellowing and I can't think of a better example than a Gibson Les Paul Silverburst.

I shudder to think what this is going to look like 30 years from now if it's ever taken out of its case and Mr. Sun gets his rays on it.

1643535810127.png
 

LtDave32

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I've got a 2003 Gibson J -185 that I bought new, which still shows no signs of yellowing.

cracks and checks, but no yellow.

some yellow more than others.
 

Brazilnut

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I think in some cases the eventual color might have to do with what's underneath it, too. A light color over ash seems to want to turn cream or yellow after a while, for instance.
 

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