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Polyurethane


daveq
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I was just spraying some polyurethane last night on a table I built and was wondering if it would work for a guitar body? I'm talking about the Minwax (or other) polyurethane spray can stuff. It seems to have a fairly thick build but I have no idea if it would finish like nitro or other types of clear.

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Your asking a question that's opinionated.. so all i can do is give you my opinion... I personally don't like the Minwax Polyurethane.. it's not the same kind that Fender, Paul Reed Smith, Gibson uses... It takes a long, long time to cure out.. and if your in any kind of hurry, then you shouldn't use it... Most guitar manufactures use Automotive Poly.. which is alot better... I've heard some people trying to use the Minwax spray with limited success but then again, I have only tried the product one time, and quickly gave up on it.. lol. I would assume though that since none of the leading guitar manufacture use it.. then it's not as good as the automotive poly... or they'd be using it.. Right? So basically to sum it up, automotive poly cures alot faster, is more durable, and polishes up to a ultra shiney finish. You can use what you want, it's your guitar, but If I was looking for a finish that rivals other manufactures, then I'd use the same thing they used or better.

Matt

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Does the automotive stuff require strict temp/humidity?

Depends on what kind of activator you use. You'll mix the activator with the paint before you spray, and you can buy activator for higher temperature, or for lower temp.. some can be for all though.. but saying all that. It is better for a temperature of 72 deg and low humidity with the right activator.

*What brand of automotive do you use?

Currently I'm using Dupont's cheaper brand Nason Select Clear to do the clearcoating. I had read where that PRS used Dupont ChromaPremier paint.. so, I went to buy some, we'll.. it's alot higher and the guy said that the Nason would do as good of a job so I went with it. Later on a friend who used to paint cars some, gave me a quart of ChromaPremier 7500s, and haven't got to try it yet. But I talked to a guy who paints cars for a living and asked him if there was a difference.. He said that the ChromaPremier is the best and the finish is easier to put on, but that the Nason Select Clear is ok if you are careful. I'll let you know if I can tell any difference at all after I try it on my next guitar. So basically I use Dupont paint.

*What equipment is needed to spray it (is it a spray can or something you put into a spray gun)?

You will need to have a air compressor and a spray gun. There are many types, but you'll need to use or buy one that is big enough to push the right volume of air. Also, the spray gun selection is large.. you can pick conventional gun, hvlp gun, and both types work great. The main thing I'd look for is that it is a gravity feed gun, which are really nice. So no it's not in a spray can.

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Also, the spray gun selection is large.. you can pick conventional gun, hvlp gun, and both types work great.

Thanks, I have some spray equipment now but I wasn't sure if you were talking about a spray can in your original reply since that was what my post was about. I was hoping for a qiucker/easier way but when it comes to finishing, that doesn't seem to exist.

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if you are going to spray automotive clears, the MOST important piece of equipment is a VERY good respirator. Also, check local codes, I know here where I live it is very illegal to spray automotive or any cyanide based paint in a residential area without a proper filtration system (paint booth) Chances are you would never get caught doing the odd guitar, but if you are planning to do a few it's worth checking into. Read my painting tutorial, I discuss clear coating with automotive paints. I also did some comparrisons of many different types of paints if you read the tutorials I wrote.

IMO automotive clears are the best way to go, but be prepared to make a fairly reasonable initial investment. A decent gun will set you back $150, a good compressor $200 + a fresh air breathing aparatus $600+ and the paint isn't cheap either.

Here are the tutorials, the first one also talks about spray guns, and some application techniques.

Comparrisons

Painting tutorial

polishing tutorial

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A decent gun will set you back $150, a good compressor $200 + a fresh air breathing aparatus $600+ and the paint isn't cheap either.

Yowsers! I guess I'll stick to my nitro then. I have a home-built booth and that's why I was wondering about the temp/humidity for the automotive stuff. I can get the temp near 70 and the humidity hasn't been as issue so far.

Even with my booth/exhaust fan, I wouldn't feel comfortable using the component paints. It's a shame because I have heard it is fairly quick and doesn't require much sanding.

I was hoping to find something a little easier to work with than what I am currently using (nitro).

I have heard some good things about Plastikote but I have no idea what it is classified as - is it acrylic, enamel, ...? Is it worth trying? I didn't see it listed in the LGM tutorial - probably because it's not in the same class as the other types listed.

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Listen to LGM he knows what's he's talking about.. Yes your gonna need to be careful using polyurethane, but you also need to be equally as cautious with nitro. It's bad stuff also.. Your gonna want to use a good respirator no matter what. Another thing is you'll need to make sure you don't spray around anything that could cause it to ignite... the exhaust fan must be a totally sealed one (explosion proof)... And yes it's true that good polyurethane paint is easier to get a great finish...

Also, the PlastiKote spray paint is acrylic lacquer.. which is decent.

If you still want poly finish and don't have the money to invest in alot of equipment.. you should get someone you know or from a body shop to paint it for you with automotive paint if you could, not sure how much you'd have to pay, but it'd be worth it. Oh yeah and you'd be able to finish the guitar the next day.. since it cures fast....

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Heres my latest. Clearcoated with Minwax polyurethane spraybomb. I have no complaints. Not as toxic or noxious to work with as laquers and its easy to fill, sand and polish. You can also brush it on with a foam applicator and it will settle out on a flat surface like a sheet of glass. Shine has been there for 2 months now and still shinin' on.

http://pictures.care2.com/view/2/848983763

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Listen to LGM he knows what's he's talking about.. Yes your gonna need to be careful using polyurethane, but you also need to be equally as cautious with nitro.

I guess I didn't explain myself clearly. I have already used nitro - not thinking about it - already have done it. I have a respirator and spray booth (with exhaust fan). I'm not in need of a poly finish - I was just wondering if the spray can clears are worth trying.

Thanks for the info on the Plastikote.

Dave

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Usually if you take your freshly painted guitar to an autobody shop they will clear it for you. You'll still have to sand it out and polish it, but they'll lay on a nice coat of clear. Only trouble is, you'll usually only get one or two coats and that's not really enough to sand and polish. However, many times, if you give them a nice smooth surface to work with, they have great booths and won't get any dust in the finish, and they'll probably only charge you about $30 to $50

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Usually if you take your freshly painted guitar to an autobody shop they will clear it for you. You'll still have to sand it out and polish it, but they'll lay on a nice coat of clear. Only trouble is, you'll usually only get one or two coats and that's not really enough to sand and polish. However, many times, if you give them a nice smooth surface to work with, they have great booths and won't get any dust in the finish, and they'll probably only charge you about $30 to $50

now THAT'S a helpful tip :D

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Usually if you take your freshly painted guitar to an autobody shop they will clear it for you. You'll still have to sand it out and polish it, but they'll lay on a nice coat of clear. Only trouble is, you'll usually only get one or two coats and that's not really enough to sand and polish. However, many times, if you give them a nice smooth surface to work with, they have great booths and won't get any dust in the finish, and they'll probably only charge you about $30 to $50

That is a better solution to spray cans. With the Minwax I had to put a lot of coats on so I didn't get burn through when put on the polishing wheel. It really was a pain to work with.

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This is wierd....

I used some Minwax spray polyurethane lite gloss on my maple headstock of my current project. A couple coats sprayed outside in 60-degree weather and left inside over night dried to a beautiful glossy finish, looks like Fender vintage amber neck color.

BUT!

It's very hard to polish or remove, very hard to remove! I decided to do the body with Deft spray-can lacquer and it's great. A few good coats outside and it left and thin, but glossy finish that's very smooth, much smoother than the plasticy Poly finish. It dried overnight, but it took a week for the body to quit smelling like lacquer.

The Poly is really tought stuff and might be great for headstocks. I'm also going to use the Poly inside my control cavity, because the top-wood is only about 1/4 of an inch thick and I want to add as much mass to the inside of the cavity as possible.

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