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I recently used polyurethane for the first time. I was very delighted by the overall feeling. It is wonderful look, it is fast and dries so fast that you can polish it after one or two days. Above all does not shrink at all and it is so durable that looks like the perfect finish we were waiting for. Here in Italy they sell a basecoat to be used before the finish itself. Is it the same in USA? It is kind of a sanding sealer, that has good pore filling properties. Unlike lacquer sanding sealer, the poly one does not shrink over time and therefore is just perfect. The problem is that you have to use a lot of it. And if you have some pores not completely filled yet, when you sand they turn white because of the sanding powder. Have you experienced this problem? I was thinking that maybe a good idea would be to pre-fill the grain with some kind of pore filler. What's your technique for this?

Hi Enrico,

I've personally abandoned finishes with the letters "poly.." as part of the name. I used to use waterborne urethanes, but gave up.

My favorite pore fillers are shellac and pumice (old school) and LMI's micro-bead pore filler with acrylic paint added to color it. I think the same type of filler is available from other suppliers, but I just don't know what the names are.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Hi Don,
you said you gave up finishes with the word poly. I am wondering if I made a mistake in naming them. Maybe it is catalyzed urethane. This is an excerpt from froggy bottom guitars:
"Our guitars are finished with a catalyzed urethane finish. We switched to this material in 2007 after over thirty-five years of using nitrocellulose laquer. We find the modern finish superior in essentially all ways."
I guess Michael Millard knows a bit more than I do , but I totally agree with him. I don't see any reason why you did not appreciate urethanes. Are we talking about the same thing?

Also, have you tried timbermate?

We are, and it's a matter of preference. I just don't happen to like urethanes for a variety of reasons. I don't like their look, and I don't like working with them. I've never found one that doesn't look like "plastic" to me, and that's because....they are plastic. I much prefer a nitro or oil varnish. Notice the word "prefer".
A lot of folks are using UV cured polyester finishes, which are virtually indestructible. They can spray and buff out in the same day. Seems great right? They look shiny and nice, but to me lack the warmth and depth of nitro or an oil varnish. I'd rather wait and get the look I'm after.

_________________
"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

I see, and yes I agree on that. The only guitar I finished with urethane had that plastic look. I noticed nitro is much more pleasent to look. It is warmer and deeper in look. But I can live with that. Aren't you annoyed by the shrinking of laquer around pores? I sprayed a guitar one year ago and now I can see many craters where the pores are located. I guess that is part of the good looking part, right?

The key to using lacquer is really good pore filling. Once you've become good at that, then the lacquer can't shrink back into the pores and will remain level. I haven't tried the Timbermate filler, but I may try it eventually. I actually like the process of pore filling, unless I'm feeling in a hurry. When I have the time to "take my time" with it, I enjoy the process, especially the shellac and pumice method. My best successes have been with the LMI micro bead filler though.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

enricopg-

i experienced the EXACT same problem that you discussed..being that i am a beginner i started shooting my own finishes, i opted for polyurethane for the stated reasons. I didn't have any prior experience or anybody to assist me with spraying and applying the finish. the process i used was, i pore filled with CA, then i would spray urethane, and after wet sand it and spray it again....and like you said i would always get those little white pin holes with white dust.....so what i did for the last couple guitars is Pore Fill with CA and try to cover it the best i could...after i let it sit and then spray my polyurethane...once the poly is dry you can still see little pores that were missed, so before i start wet sanding, i spread another layer of CA to cover the pores that were not filled.. after it dries then i wet sand it till i get an even surface...then i shoot my final coats...after that wet sanding is a breeze given that the surface is relatively smooth and even, just some small orange peel.. and the results are great!

i will be posting pics soon

The polyurethane you refer to is a completely different coating than a catalyzed urethane. While they will tell you how superior the coating is in their ad copy the real reason for the switch is most likely faster production speed and lower unit cost. I do not like urethanes either, they are generally softer finishes and usually have that "plastic" look and lack of clarity. No matter the type of finish, good pore fill is essential. I use epoxy under my French Polish and sometimes higher end lacquer finishes but generally use an industrial paste filler similar to Pore-O-Pac under most of my lacquer and other finishes.

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Brian

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

https://www.howardguitarsdelaware.com/

While I understand the plastic look subject, I find it difficult to accept the hardness subject.
That's mainly because the brand I used was developed for wooden floors. And therefore very hard. Also I find it more difficult to buff compared to nitro.

Catalyzed Urethane, exact same as Froggy Bottom. I fill with Z-Poxy. Great finish.

How do you know its the same finish?

Actually softer coatings are harder to buff out. Buffing is the process of making continually finer scratches to polish something to a gloss, polishing compounds are nothing more than very fine abrasives. Softer surfaces do not scratch as well and as such are harder to buff out. Typically exterior coatings are the softest followed closely by those for floors. Scratch resistance is important for something like a floor that gets walked on so it remains good looking for the longest time. Also the term "poly-urethane" has become sort of a general term used to describe any type of closed finish that can not be re-disolved with a solvent, such as acid catalyzed amino-alkyds and true two part urethanes which are more like epoxies.

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Brian

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

https://www.howardguitarsdelaware.com/

I live in Chelsea, Vt. where FB's are made. Michael Millard is my good friend , and his finisher does my guitars right along side of the Froggies. This is this weeks unit: 000-14 fret Lacewood.

Care to share just what finish they are using?

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Brian

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

https://www.howardguitarsdelaware.com/

Yes please. I'd be interested in a non uv two day buff out finish....

I went through a cat-poly phase after using in on a metal body instrument but have given up on it for wood instruments. The lack of burn-in is the reason for the white specs. I found I had to use an old tooth brush, damp rags and the tip of an X-Acto to get them out of pores before going to the next coat. You can also get witness lines and adhesion problems if you don't use a promoter like Bulldog.

Between all that and the pure nastiness of the product itself I'm giving up and going back to nitro. The quick build and short cure time was nice, but not not nice enuff.

I'll have to check.

I have three guitars out being finished at the moment. I can't wait to receive them back. A luthier friend in town, Joel Stehr, uses this same fellow, Tony Fergusen in Michigan to do the finishing for his beautiful acoustic guitars. I've seen Tony's work first hand and the finish is impeccable...as clear, fine, and even as you could possibly want.

Tony uses an epoxy pore fill with catalyzed urethane topcoats. The durability is outstanding according to Tony.

I expect I'm going to finally be using catalyzed polyester for my finishes. I've gotten to the point of being able to do nitrocellulose lacquer finishes at a quality level that I think is going to satisfy a discerning customer but it simply requires too much time to process. If catalyzed systems are used it's actually possible, knowing a few tricks, to go from raw wood to a polished finish in three days. It would be a focused effort to be sure but it is possible.

I think, for me, the catalyzed finishes are going to require a better grasp of the art of pre-coloring or dying bare woods. With the catalyzed polyester there are only two topcoats applied and I worry about about being able to spray even color coats. I had a very nice talk with Scott Walker who laid out the dying process he uses to absolutely POP the figure of his Maple facings. In his case, all the color is applied prior to the application of topcoats. My initial experiments with test panels convinces me that this is a good way to go.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I'd been sending my instruments out for Nitro for the last 7 years but recently switched to Tony for Catalyzed Urethane. I would take issue with the statement that the Cat Urethane is "plastic looking" compared to Nitro. I would say Tony's finishes have every bit as much the depth and beauty of a good nitro finish. He does beautiful work, very thin, and with meticulous attention to detail. I have not been able to tell any sonic differences compared to nitro. I like the stuff and I was a real nitro fan.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I use trans tint in alcohol for stain to highlight curl or figure in wood, prior to finishing. For color coats I use House of Color. They've got all kinds of cool colors. I use a coat of isolate, the house of color base coats, another coat of sealer, then Polyester for top coats. The House of Color has almost no build so it doesn't make the finish get thick, like tinting top coats can.

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

The issue of "looking like plastic" can usually be traced to too-thick applications, usually on cheap imports. Polyester builds like crazy on and in corners, even on an otherwise thin finish, completely opposite of what nitro lacquer does, such that if not carefully sanded to 'sharpen" those edges, the overall "look" can be plastic-like. It's a subtle effect, and one that most persons looking at the object wouldn't/couldn't quite explain, but they'd know it.

As for clarity, a good catalysed polyester finish will be as clear as a new nitro finish, and remain that clear forever, where the nitro finish will begin the yellow and age from the day it was sprayed, and continue to yellow and age forever, always losing more and more of its clarity.

When I do colors, ALL the colors go down before the polyester topcoats. The topcoats go on clear.

And where'd you get the notion that you can only apply 2 coats? You can shoot as many as you wish, but must always watch the timing between coats. I typically shoot 3 to 4 thin coats, and will not think twice about doing a 5th coat if there was something about the previous coats that gave me concern or will cause me to do more leveling than usual(for example, if I found and removed a large dust particle or hair in the 3rd or 4th coat and it left a large-ish "squiggle").

As for polyurethanes, be aware that even the hardware store varieties will require a barrier coat on the more exotic woods(rosewood, ebony, etc...) or they will likely not cure well. After becoming sensitized to nitro back in the last Century, I tried just about everything, including a good amount of (poly)urethanes, and none would cure completely over most rosewoods.

If you really want to use an off-the-shelf, out of the can hardware or paint store finish that can be leveled and buffed, yet can still be applied at home either by spray or brush, try one of the proven oil varnishes that many of us are using/have used.

Hi,

Coming late on this one, sorry.

I finish all my guitars with brushed on Minwax fast drying polyurethane. Once I got the hang of it (took me about 13 guitars, but most of the learning curve was regarding finishing on its own, not specifically about learning how to use polyurethane), so once I got the hang of it, absolutely no one ever mentioned anything about my finishes not being up to standards. I agree with Mario that the plastic looking aspect probably comes from too thick of a final film.

Regarding polyurethane not curing well over rosewwod, I indeed had to struggle with that, but the solution turned out to pretty easy: two coats of Zinsser Seal coat (which is essentially dewaxed shellac) and voilà. I have never had issues over rosewood since I used this solution.

Regarding the well discussed problem of witness lines when sanding through a coat or when doing touch up, when the poly is resonably fresh (from a few days to about a year), I was always able to buff them away without much hassle. Its when the poly is old, like many years, that I was not able to hide the witness lines, and only when reparing on flat surfaces, like the top or back. When there is some curve in the surface being touched up, the witness lines are there, but pretty hard to find, unless you really look for them.

I have to say I would rather use nitro, but I'm not in an environment where I can use it. Until I move the shop out of the house, I can not spray. And polyurethane is the easiest, fastest way I have found to finish a guitar to the high end standard we all expect. And the drawbacks have not been important enough to find another solution.

Hope this helps!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Ya...that applies to the Seagraves topcoat I have. They suggest you can actually lay down 8 mils in one pass. Testing it....I doubt you'd want to try that on a guitar but laying down two, thinned topcoats of this stuff will certainly be enough material. I also have a package of Simtec polyester sealer and topcoats. I think that's going to be a better fit for me because it looks to want to lay down thinner just looking at it in the can. We'll see.

Peroxide based catalysts tend toward a highly predictable curing schedule so polyesters, for me, provide a wide latitude of processing capability. Also...you can thin it pretty much to your heart's content with acetone. You can also catalyze it lean or rich to control how fast it cures (within limits), or use heat to speed the cure at a given catalyst ratio. Polyester, applied in a thin film will set to a substantive layer long before it fully hardens....so if you want to lay down successive coats there is a wide window to recoat without sanding.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Share your schedule Alain?

They suggest you can actually lay down 8 mils in one pass.

Yeah, that's possible, but that's also where you'll end up with that "thick, plastic-like look". Polyester wants to run to, and build, in the corners and edges, and shooting a 8 mil thick coat will do that! Been there.... I'd much prefer to shoot 3-4 coats at 1.5 or 2 mil. The final 'look' is right, and there's less chance of messing up, getting runs, etc.... So it takes a bit more time; no biggie!

Remember, the folks who make these finishes make them for large industries, so their recommendations need to be viewed not from their perspective, but from ours. When I tell a rep that I only need to mix and shoot 1-1/2 ounces of barrier/isolator at a time, if they don't hang up outright(assuming I'm a prank caller, or time waster, I imagine?!?), there's at least a long pause before the conversation resumes...

Also...you can thin it pretty much to your heart's content with acetone.

Oy! Acetone is a very fast evaporator; if you haven't yet tried it, MEK is a wayyy nicer thinner. Been there, tried that, ain't looking back... But why thin more than necessary, anyhow? 10% is more than enough. If your gun needs a lot of thinning, you need a larger tip and needle.