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I am wondering why so many people are using polyester? Does it have some benefits over lacquer?

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Polyester is certainly a lot tougher than lacquer! With a poly finish there's probably no need for a pick guard. In theory it seems it could be applied thinner, which would (again, in theory) help offset any affect on tone that the stiffer poly finish might create. Some pretty high-end luthiers are using poly, so there may be something to it. Check out this thread from several years ago...

viewtopic.php?t=13299

Taylor uses it and they are generally considered to be nice sounding for a factory guitar. It is Tough with a capitol T. From a repair stand point it's a bit of a nightmare compared to lacquer. CA is about the only spot repair that works that I have found. If the polyester cracks it will always blackline after a repair. No worse than most poly in the end. Have also heard that the uncured finish is some nasty stuff but I don't know how true that is.

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Brian

You never know what you are capable of until you actually try.

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In addition to Taylor, I believe Larrivée, Olson, Goodall, Huss and Dalton, Bourgeois, and two-thirds of a Collings guitars are finished with polyester.

Below is another good thread on UV cured polyester. The UV cure appeals to me because, as Brian mentioned, polyester is nasty stuff and I believe a lot of the nastiness is in the catalyst. Someone please correct me if I'm wrong about that.

viewtopic.php?f=10101&t=32886&hilit=+polyester

I use Polyester (but offer oil based Varnish as an option.) I won't get into a Polyester vs Lacquer comparison because my opinion is merely my opinion.
Polyester is potentially DANGEROUS though, and requires proper safety equipment and precautions. It also has a relatively short shelf life, compared to most finishes. PM or e-mail me if you'd like to know what I use, and my finishing schedule.

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Most factories that use it do so for the instacure aspect of it. Prep Monday, buff Wednesday morning...

Actually apply, cure and then buff with no need to wait at all. It's definitely done for production speed.

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Brian

You never know what you are capable of until you actually try.

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The value of polyester is that it can be applied incredibly thin and still offer great protection. Most of the factories don't take advantage of this fact and spray the finish as thick as regular lacquer. Joe White who does my finish work routinely sprays a film on the soundboard that is 0.002" to 0.003" thick.

The other advantage is cosmetic. The full cure aspect means that the finish doesn't continue to sink into glue lines (around purfling, rosettes, etc.) This happens with all other finishes that I'm aware of but polyester will still look identical in this regard, several years after it was first buffed. Some folks actually like the finish sinking into the glue lines but I don't and almost every person I know doesn't like that look either.

One negative is that it is not easily repairable although there are folks who can do a great job repairing polyester (but that won't be a skill set everyone has).

Simon - those are some good points. Do you find you get a pretty high gloss with the poly?

Which I believe is also good for tone. It takes lacquer literally years to completely cure. A guitar with a THIN Polyester finish will sound "broken in" really quick.

According to a friend of mine who sells finishes at least 2 resonably big American guitar companies (not Martin) use Polyester, with a thin coat of lacquer on top. Lacquer is easier to buff than Polyester, and they get to advertise a "Lacquer finish". In reality if you took a rag soaked in acetone, and wiped the lacquer off you'd have a thinner, more acoustically transparent finish.


Polyester can be buffed to an excellent gloss. It's harder to buff than Nitro though. Buffing involves scratching, and removing the previous scratches with finer scratches. Lacquer is hard and brittle, so it's easy to scratch. Polyester is very flexible. It's harder to scratch, so it's harder to buff. This is a Polyester finish.


I'm sure Simon's got some pictures of glossy Polyester finishes too.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Cam someone tell me why poly can be applied thinner than other finishes? Does not compute...

I think what the others are getting at is that the final film thickness can be thinner than a nitro finish with superior protection to the instrument. Has nothing to do with the actual application.

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jw ( o)===:::

So if all films were equal, poly would be tougher? But one could get any finish sanded and buffed at .002-.003?

Polyester is tougher. It's also more flexible. It doesn't shrink much, and doesn't shrink at all after a few hours. A .002" thick newly applied Nitro finish would be pretty much non existent after a couple years, as nitro takes a long time for all of the solvents to evaporate. As these solvents evaporate it shrinks.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

A very thin film requires a tough finish to offer adequate protection. The finisher has control over the thickness of the finish and can apply a very thin film or a thick film and every point in between. I think most of us agree that a very thin film is ideal for good sound production; however, I wouldn't want to have a lacquer finish that is 0.002" - probably more like 0.005" to 0.007" to offer adequate protection.

As mentioned, this polyester stuff requires that you know what you are doing and take adequate safety measures. I personally wouldn't be using a polyester finish if I were doing my own finish work -- that's why I subcontract out that part of my build process to someone who is able to handle working with the material.

Joe - may I ask what polyester finish you use? Thanks!

Polyester resin....as a previous hobby surfboard builder all I can say is that it works great with fiberglass for a strong matrix...boats, too. And quick, too...hardens overnight.

Maybe technology has come a long way....IIRC there's laminating resin, sanding resin (wax added), gloss coat and casting resin...based on refining levels....hopefully you guys are using gloss or casting resin for clarity....but usually takes a coupla hours to 'go off'...it is very hard and durable next day.

It's toxic, messy, viscous stuff (methylethyl ketone peroxide, acetone)....but it falls in line with the epoxy folks for applicability, I guess....also, there's the UV option, too.

The main advantage for a factory is labor. Polyester shrinks very little, and requires less coats and less level sanding to get a glassy smooth surface. That is why polyester is almost universal on low end Asian guitars.

Collings is one of them. By using a polyester base coat, the leveling of the finish is much less labor-intensive, and the finish stays level. With lacquer, it is a battle. Level the finish one day, and two days later it has shrunk into the pores. That requires more leveling, and possibly more coats of lacquer.
Lacquer that is ready to spray is about 20% solids. That means that 80% of what you spray on the guitar evaporates away. I don't know the exact figure for polyester, but I think it is probably about 75% solids. Big difference.

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John

I have use polyester (ICA) finish on some target rifle stocks I have made. Its amazingly tough and you can get about any candy color you want. You must have a dedicated spray booth and proper ppe.

Lacquer that is ready to spray is about 20% solids. That means that 80% of what you spray on the guitar evaporates away. I don't know the exact figure for polyester, but I think it is probably about 75% solids.

The polyester I've used is 92% solids! That's why it is so easy to build-up a thick finish with the stuff; if we sprayed it like we did lacquer, with the mindset that 80% of what we sprayed will disappear within a few hours, we would end-up with a very heavy finish. It takes a whole new mindset to shoot just a thin layer onto an instrument and walk away!

As others have said, polyester is both tough, and very flexible, more so than any lacquer. Because it is tough and will not shrink over time(if it does, it will be minimal), we can get away with a much thinner final finish, which we all agree is beneficial to tone and power.

In discussions with one of the manufacturers that does the lacquer-over-polyester thing was that they do it because the polyester is an excellent clear pore filler(I can attest to that!), and it's fast. Their reason for topping it with nitro lacquer isn't so much about marketing(IE: being able to claim a traditional nitro lacquer finish), but rather about ease of repairing small scratches and dings, at the factory, the dealer's, as well as in the years to come. And yes, it is a good bit quicker and easier to take a nitro lacquer finish to a crystal-clear gloss than it is to take a polyester finish to the same gloss level. It can be done, but requires a good many more compounds(finer and finer) and a deft touch at the buffer. Repairs to small scratches and dings are also possible, but again, much more time-consuming.

Bottom line is that it is an excellent finish for stringed instruments, but the Asian factories that use it in a uber-heavy thickness on uber-cheap guitars have long given it a bad name...

Oh, and also..., while polyester finishes are indeed related to the polyester resins used in fiberglass, they are NOT the same at all, each one formulated specifically for their intended use.

ICA Charlie.

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jw ( o)===:::

Thanks Joe!

I don't use polyester because I really do not have the facility to spray it... so I stick with lacquer.

Despite all the possible benefits of polyester I can't really do much with them, and its a lot less forgiving in terms of application. It suits production very well and once you get the process down and have enough volume, it works great and have minimal impact for the tone. For my volume, and the fact that I take on repairs, I really can't use poly.

I actually prefer french polish shellac but for repairs I go with lacquer just because there aren't too many french polished guitar out there that came into my shop...

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Grumpy, or any of the others from the 2007 thread,

Have your methods/materials changed much from the thread from a few years back? The Solarez seems to be a new product since then, or maybe a similar product in a new jug. The sunlight cure is quite appealing, if the end result is similar to the McFaddens, ICA, or Chemcraft. I have a nice big window in the shop I could cure with, without having to go outside into the dust and bugs. I suppose any of the UV products will eventually cure in sunlight, but assume the Solarez is formulated to to cure faster/more thoroughly? Anyone know if this is a correct assumption?

How about the bridges SuperT'd to the polyester? It's been 5+years, if there have been no failures, that's a pretty good indication of success.