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Post subject: What exact type of Polyurethane is used?
Posted: Fri Jul 31, 2015 12:52 pm
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I’m interested in refinishing a project Telecaster body I recently purchased. I’ve heard that most guitar manufacturers use Polyurethane because it provides the best and hardest protection against dings. I have used spray polyurethane before and it buffs out nice, but even after several months of curing, if you dig a thumbnail into the finish it will leave a mark. My question is, what exact type of Polyurethane are instrument companies using? Based on my experience, it must be in a different league than what is commercially available to the consumer. I’ve heard about 2-part urethanes that have a small bottle of “cross linker” to add to them. Is this what is being used, perhaps?


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Post subject: Re: What exact type of Polyurethane is used?
Posted: Fri Jul 31, 2015 1:50 pm
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Poly finishes these days are UV-cured, which hardens them quickly.

On cheaper guitars, you'll often find polyester, in a much thicker layer than the polyurethane.
And on more expensive guitars, nitrocellulose is still premium, or other solvent based lacquers for matte finishes.


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Post subject: Re: What exact type of Polyurethane is used?
Posted: Thu Aug 06, 2015 12:15 pm
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I really don't know what type of poly Fender (or other makers) use...I'm sure I read about it when I was learning refinishing and arth1's comment about UV cured sounds right, but that could just be the dead brain cells talkin' too.

That said and for what it's worth, while I haven't actually tried one on a guitar yet, in general, I've found commercial polys to be a real pain to work with. I suspect it's probably due to my technique more than anything, however I've always found it very difficult to get that "glass-like" finish with poly, both in terms is visual appearance and texture. I'll admit right off the bat that it's a trade off in regards to "durability", however personally I've found that lacquer really works the best for me. ReRanch provides a good deal of info on guitar refinishing (assuming you haven't already looked them up) as well as some great products (I'm told), but I actually just use car lacquer most of the time...same stuff the hot rod guys use and it does a really nice job. In fact for one bass restoration I did (a Yamaha Motion B), I actually just used some rattle can lacquer from the local hardware store and it did a really decent job...had to do quite a bit more sanding with the rattle can of course, but still produced a very nice finish. That said, lacquer of course has the same problem as you describe...just takes FOREVER to dry.

If you are in fact looking for something that's fast drying, I might almost suggest experimenting with acrylic. As one of my art teachers put it, "it's like painting with liquid plastic" and while again I've never used this on a guitar, from my art experience I can tell you that it tends to dry REALLY quick.

Ultimately I suspect you're gonna have to deal with trade off's no matter which way you go. My advice would be to decide what your priorities are, do some experiments on some scrap wood and make your decisions from there...i.e., if you're exclusive concern is making it look good, a lot of folks (myself included) favor lacquer. Poly is durable, but I suspect that arth1 is correct in that there are special processes involved.

BTW...if this is by chance your first refinish, I would strongly urge you to do some test pieces before you start on the guitar...it might even be well worth picking up a really cheap guitar off Craigslist to practice on. I can't speak for others, however when I got into doing refinishing, it took me a good 12 to 15 attempts before I was really comfortable with my results...I have 2 guitar bodies here that got sprayed and stripped MULTIPLE times as I was learning. It's tempting to just dive right in, especially if you have other finishing experience, but if you value this project, a bit of patience and some experimentation may produce better results.

Just my $.02 worth.


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Post subject: Re: What exact type of Polyurethane is used?
Posted: Thu Aug 06, 2015 12:34 pm
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lomitus wrote:
If you are in fact looking for something that's fast drying, I might almost suggest experimenting with acrylic. As one of my art teachers put it, "it's like painting with liquid plastic" and while again I've never used this on a guitar, from my art experience I can tell you that it tends to dry REALLY quick.


That does not match my experience from woodworking. While it's easy to get a shiny finish with acrylic lacquers, and they touch-dry quickly, they also cure extremely slowly on hardwood, to the point that if you press hard, you can make a fingerprint stick weeks after painting. And most of them are not UV safe, so you risk the finish going cloudy or losing saturation if subjected to direct sunlight.


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Post subject: Re: What exact type of Polyurethane is used?
Posted: Mon Aug 10, 2015 7:39 am
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arth1 wrote:
lomitus wrote:
If you are in fact looking for something that's fast drying, I might almost suggest experimenting with acrylic. As one of my art teachers put it, "it's like painting with liquid plastic" and while again I've never used this on a guitar, from my art experience I can tell you that it tends to dry REALLY quick.


That does not match my experience from woodworking. While it's easy to get a shiny finish with acrylic lacquers, and they touch-dry quickly, they also cure extremely slowly on hardwood, to the point that if you press hard, you can make a fingerprint stick weeks after painting. And most of them are not UV safe, so you risk the finish going cloudy or losing saturation if subjected to direct sunlight.



On how quickly acrylics cure...again I've never tried it with a guitar (or wood in general), so I'll defer to your experience there. I just remember hating the stuff back in art classes at college because the stuff seemed to dry AS I was painting with it...found that REALLY annoying, particularly when we had to mix 15 shades of 15 colors for doing our color charts. Oils would have been SOOO much easier to work with. That said, these were art acrylics...the tubes of paint that you'd buy at an artist's supply store, so I really don't know how they'd compare to other commercial products as far as curing time goes...again some experimentation might be interesting.

As far as the UV issue...hmmm. First off here, while I'm not sure about UV "safe", I do certainly know that there are UV "resistant" acrylics out there...I've seen them from companies such as Krylon and Liquitex. Likewise, if exposure to direct sunlight is in fact THAT much of an issue, there are also products such as Lascaux UV Protect that can be applied over acrylics to address that specific issue. With this in mind, one might question just HOW much of an issue this really is...

I guess this falls under that whole YMMV thing, but in my 30 years of playing, I honestly don't remember ever doing a gig in direct sunlight. The vast majority of gigs I've done over the years have typically been in darkly lit bars and clubs (I really miss being able to smoke in those places...). Even when it comes to practices and jams, it's typically in someone's basement or garage somewhere where any exposure to direct sunlight is EXTREMELY limited. Even the few outdoor gigs I have done over the years were typically in some form of shade...either in a pavilion or tent or something of that nature. I have no doubt that there must be a few people who play regularly out in the afternoon sunshine, but that strikes me as being the exception rather than the rule.

That said however, one could argue that in regards to color, for some people there's maybe a bit of appeal as to how a given finish may age with time with regard to such things. I don't remember which book it was, but I remember reading something of an analysis of "Lake Placid Blue" (which caught my attention because I have 2 Strats in that color) where they showed several different examples, ranging from a deep blue to almost an aqua green. Very simply, even if you took the most resilient poly finish out there and left it sitting long enough in direct sunlight, I suspect that sooner or later it would in fact discolor...although I would question as to why someone would do that with a guitar to begin with. Me thinks that if you're frequently leaving your guitar sitting in direct sunlight, that paint discoloration would be the last of your worries.

As an artist and particularly as a photographer, I'm aware (rather painfully so) that some people can in fact get overly obsessive about "color", however in guitar terms, regardless of the paint medium, unless the guitar is kept exclusively in a light tight, hermetically sealed enclosure of some kind (in which case, what's the point?), some degree of discoloration should always be expected with time. Obviously everyone is going to have different needs, if not different expectations, however unless I had done a guitar finish as some specific piece of art work (say an air brush finish or something), that's just not something I'd get too overly concerned with.


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