.05mm Thick Nitro Finish???

[wallis222]

I'm having one of my Telecasters refinished and I requested a thin finish. The guy who is doing the work for me responded that all of his clear nitro finishes are only .05mm thick, about half the thickness of a high E string. That sounds impossibly thin to me. He said that a lot of boutique builders are finishing their guitars this thin...I can't find any reference to this online. Anyone ever heard of this before?

I'll be happy if this is true - the thinner the better if you ask me.

Also, how would this compare to a stock Fender nitro finish? Or how would it compare to the guitars coming out of Fender's Fullerton, California factory back in the good old days?

Thanks guys.

[conorb]

.05mm is approximately .002" which is really, really thin. About 3 times thicker than standard household aluminum foil which is about .016mm.

Or slightly thinner than a "normal" human hair" at somewhere between .04mm and .075mm. Of course, this depends on the human and the hair but from an order of magnitude pov .05mm is *thin.*

conorb

[piece of ash]

0.05mm is nearly equivalent to 0.002 inches. This is anywhere from 1/4 to 1/6 of an e string. This is about the thickness of low grade printer paper.

Your finisher is not too kean in the math department... so I wouldn't take his thickness quote too seriously.

Thin finish is important with violins, acoustics etc... It don't mean squat to a solid body. The wood does not need to breathe either... it is dead after all.

This 0.002 inch thick finish may be 1/5 to 1/30 of the entire finish found on Fenders then and now.

[wallis222]

Thanks guys.

Just what I though... impossibly thin. I bet what he meant to say was .5mm

That seems more reasonable, and still very thin.

[piece of ash]

It's not impossibly thin...

But, any given piece of wood is going to have peaks and valleys on the order of 2 to 6 thousandths... so just to get a smooth base might 8-10 thou'... then color... maybe clear...

[wallis222]

Originally Posted by piece of ash

It's not impossibly thin...

But, any given piece of wood is going to have peaks and valleys on the order of 2 to 6 thousandths... so just to get a smooth base might 8-10 thou'... then color... maybe clear...

All he is using is a shellac sealer coat (pine body) and then nitro. Maybe it's possible that he is using only .05mm. of lacquer over the shellac sealer. Anyway, I'll be seeing him need week so I'll ask him to clarify.

[tdarian]

Originally Posted by piece of ash

It's not impossibly thin...

But, any given piece of wood is going to have peaks and valleys on the order of 2 to 6 thousandths... so just to get a smooth base might 8-10 thou'... then color... maybe clear...

Curious how you are measuring this stuff.:

[Colt W. Knight]

IDK what the numbers are, but from my personal experience, you can achieve a very thin finish using nitro lacquer. Much thinner than I can achieve using oil/water based poly or acrylic lacquer. Even my thicker finishes are thinner than the common Fender finishes which are applied extra thick so they can buff the hell out of them without burning through the finish and grain fill.

[Arbiter]

0.05mm is nearly equivalent to 0.002 inches.

When I did production nitro finish on acoustics, my average finish thickness on buffout was .007 inches, not to be higher under any circumstances than .009 inches. I would not consider those guitars to have a thin finish although it's far thinner than what you'd find on any electric. My predecessor at the job ran about .004, world class finish to be sure but he had a bit more time on his hands to do them without burning them through. While .002 inches is unnecessarily thin, in my opinion, it's certainly not undoable.

As to whether you think this is treatment that should be extended to a solidbody, well, sooner or later you'll figure the answer to that out for yourself. I think it should. Not because it necessarily makes any difference to the sound, but simply because this is how a proper wood finish is done. Just because the guitar is a solidbody shouldn't mean that the instrument gets shortchanged at any point in the construction process.

Pride in craftsmanship matters. I'm glad the OPs guy is going to do it with some respect for his guitar.

The OPs other question:

Also, how would this compare to a stock Fender nitro finish? Or how would it compare to the guitars coming out of Fender's Fullerton, California factory back in the good old days?

This would be substantially thinner than either one.

[Keyser Soze]

Originally Posted by Colt W. Knight

IDK what the numbers are, but from my personal experience, you can achieve a very thin finish using nitro lacquer. Much thinner than I can achieve using oil/water based poly or acrylic lacquer. Even my thicker finishes are thinner than the common Fender finishes which are applied extra thick so they can buff the hell out of them without burning through the finish and grain fill.

I'd agree, and think this is particular to the characteristics of nitro - the relatively high solvent compenent coupled with the skin effect allows for good flow out but also even coverage and drying.

I suppose it would be possible to create finish as thin as the builder describes, but I think you could only reliably achieve those results on a very smooth, impermeable, and rigid surface (e.g. sheet metal, PVC, etc.) Anything as porous, uneven and mobile as raw wood is not conducive to routine success.

Sure you could vinyl seal and sand a nice even surface film, then shoot three layers of nitro and buff it out, then call it a super thin nitro finish. But only if you ignore the thickness of all the stuff providing a suitable surface for the nitro.

[piece of ash]

Originally Posted by tdarian

Curious how you are measuring this stuff.:

Just knowing the sizes of pores in typical wood... nothing mystical.

[K-Line]

Too thin and it will flake. You need at least 6 coats of nitro to at least have some sand back ability as well. I think there is some decimal points out of place. Thickness does matter. The more you add, the less the wood matters.

[Silverface]

OK, sorry, gotta pull rank... ;-)

First -

.05mm thick, about half the thickness of a high E string.

is wrong. Strings are measured in mils - thousandths of an inch - not millimeters. .05mm is less than 1/4 the thickness of a .008 E string.

OK - Until I recently retired I was a coatings inspector/consultant, and I have dealt with this subject professionally since 1975.

.002" is known in the trade as "2 mils", and is a very typical dry film thickness for a single coat of lacquer. An average house paint goes on at 2-4 mils DRY film thickness. There's a specific way to calculate dry film thickness from the thickness of the wet film as applied factored by the "solids by volume" of the coating (the percentage of the applied product that does not evaporate). This does not take into account material waste, overspray, etc (known as "loss").

The theoretical coverage of any coating is based on the following formula, and it is consistent no matter what type of coating (lacquer, latex paint, troweled roof coatings - it all works the same way): A 100% solids-by volume liquid applied at 1604 square fet per gallon will yield a coating of exactly 1 mil dry film thickness. If the coating has 50% solids by volume, the yield is 802 square feet at exactly 1 mil.

Most bulk (gallon or quart can) lacquers run in the 15-30% solids by volume range.

Using the formula given, if a lacquers' recommended application rate is "450 square feet per gallon" and you know the solids by volume (almost always printed on the MSDS - and DO NOT confuse this with "solids by weight", which is irrelevant from a coverage aspect) is 25%, you can do the math and figure out how thick each coat should be. There are inexpnsive tools used to masure WET film thickness (dry film measuring gages, OTOH, run in the mid-hundreds to thousands of dollars):

http://www.gardco.com/wetfilm.cfm

If a lacquer's recommended coverage rate is 450 square feet per gallon per coat and the solids by volume are 25%, then just do the math - 1604 divided by 450 = 3.56...so if 1604 square feet per gallon at 100% solids yield 1 mil dry film thickness (.001") 450 square feet at 100% solids by volume would give you 3.56 mils dry film thickness.

BUT - we have only 25% solids by volume.

So multiply 3.56 by 25% and your recommended dry film thickness per coat is .89 mils - or .0089" per coat.

That's LESS than one thousandth of an inch.

From a practical standpoint, when you measure the loss (mainly overspray) during most guitar coating operations (not due to lack of skill - most because of oddly-shaped surfaces) the PRACTICAL coverage is FARR less than the theoretical coverage (info to follow).

So the actual coverage per coat is more in the 1/2 - 3/4 mil (one mil = .0010", so 1/2 would be .0005" and 3/4 mil .00075").

So what the finisher is stating is absolutely within the bounds of good painting practice (go thicker than recommended and you'll likely get runs). 2 mils is absolutey not "too tin" nor will it result in flaking - film thickness alone has no bearing on flaking, which is an adhesion - not thickness - issue, except in the case of coatings applied TOO thickly!

And no - it is NOT impossibly thin. Also, stating that "you need to apply "x" number of coats to get "fill in the blank" results" means nothing unless the exact thickness of those coats are specified.

Sidebar - measuring tools are vital. Journeyman lacquer applicators cannot guess at how thick a coat they have applied is within an accuracy factor of +/- 200%! And every change of material requires measured test passes to verify thickness accuracy. 35 years and I still measure wet film thickness of test passes regularly.

If you painted interior walls on your house, each coat went on wet at about 4 mils - the thickness of a business card. And it dried to about half that.

Paint is applied FAR thinner than most people realize. If you peel of a chunk and feel it you think you're holding something pretty thick - but unless it's years and years of coats, it's very thin.

Extremely thick, textured rubberized (or flexible urethane. or polyurea) deck coatings used for parking decks as a waterproofing system are applied - when you add up all the coats - at about 100-120 mils DFT (dry film thickness).

That's around a TENTH of an inch. 3-4 business cards thick.

I hope that clears up the reality of coatings thickness.

One last note - the loss factor is a really important one with lacquers. HVLP (under 4 PSI) has the best transfer efficiency - i.e. more of the paint actually stays on the surface (25-30% is lost regardless of skill level). Aerosols are next but by quite a wide margin, with a 50% loss rate IF applied skillfully. Conventional spray - a compressor and gun, usually run at 30-80PSI - results in an average of 66% waste when used by professionals, 80% by amateurs - in other words, if an amateur sprays 10 gallons of lacquer with conventional equipment, somewhere between 6-8 gallons of it never hits (or sticks to) the surface!