Tips on Spraying a THIN, Vintage-Style Nitro Finish

TheFullMonty

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Hi All,

I've been doing repairs for years now, but am just now getting into some occasional full refinishing of some personal builds and projects. I have Erlewine's book on finishing, and have found it to be full of useful information. My ultimate goal would be to achieve something similar to the ultra-thin and sunken finishes on 50s Fenders, that are accurately replicated by folks like Danocaster, Carson Hess, etc.

My issue is this: once I've built my clear coats thick enough to prevent burn-through into color coats during my polishing process, the film is much too thick and glassy to replicate an old finish. Any artificial aging is made extremely difficult and unconvincing.

I am using the Qualspray AM-5008 LVLP gun from LMI spraying at around 10 PSI. My clear coat lacquer is 70% Colortone traditional aged gloss from Stewmac, 20% acetone, and 10% Colortone lacquer thinner.

Once a bare wood body is prepped, my typical finish schedule is as follows:

1. Wipe on a thin layer of dewaxed shellac as a sealer. Wait 24 hours.

2. Pore fill if necessary. Wait 24 hours.

3. Spray first coat of sealer. I use my regular lacquer as a sealer. One "coat" is comprised of the following:
--One VERY light mist of lacquer over the entire body to promote adhesion. Wait 30 seconds.
--One medium/light coat of lacquer. Certainly more than a mist coat, but not nearly heavy enough to approach running.
--Wait until first coat is dry to the touch, roughly 1 minute. Blow off the body with spray gun to accelerate drying time.
--Spray a second light/medium coat. Hang up and wait for ~2 hours.

4. Spray second coat of sealer. Wait 2 hours.

5. Spray third coat of sealer. Wait 24 hours and level/scuff sand if necessary with 400 wet/dry.

6. Spray first light color coat. Wait 2 hours and repeat 1-2 times until full coverage is achieved. Wait 24 hours.

7. Spray first clear coat .Wait 2 hours. Repeat 2 more times the same day. Level sand with 320 wet/dry if necessary after 24 hour dry.

8. Spray fourth clear coat .Wait 2 hours. Repeat 2 more times the same day. Level sand with 400 wet/dry if necessary after 24 hour dry.

9. Spray seventh clear coat .Wait 2 hours. Repeat 2 more times the same day. Level sand with 600 wet/dry if necessary after 24 hour dry.

10. Spray light wash coat, a ~70/30 mix of retarder/lacquer. Wait ~14 days.

11. Level sand with appropriate grit based on flatness, usually 800 wet/dry.

12. Remove previous grit scratches with 1k, 1200, 1500, and 2k respectively.

13. Wheel buff with Menzerna brown medium compound, followed by the fine white bar.

14. Hand rub with Colortone swirl remover.


If I reduce my number of clear coats or coat thickness, I tend to blow through my color on the body sides and edges by around the 1000 grit mark.

So, does anyone have any insight on what I may be missing?

Thanks in advance,
Monty
 

Silverface

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I have Erlewine's book on finishing, and have found it to be full of useful information

once I've built my clear coats thick enough to prevent burn-through into color coats during my polishing process, the film is much too thick and glassy to replicate an old finish.
Uh-oh!

Please understand that his book is ONLY applicable to Colortone lacquers and a few others that are blends of lacquers and oil-based enamel. They are NOT conventionqal nitrocellulose or acrylic lacquers and have an extremely long DRY time.

Please note - "DRY time".

Dan talks about "cure" time - and that is completely wrong unless you are working with chemically or light reactive lacquers - which you do not find at Stewmac or most paint stores.

LACQUERS DRY ONLY BY EVAPORATION OF THE VOLATILE COMPONENTS - SOLVENTS, SURFACTANTS (FLOW INDUCERS) QAND A FEW OTHER MINOR COMPONENTS.

One properly applied coat of CONVENTIONAL lacquer - Mohawk, Valspar, Sherwin Williams, Cardinal, Rust-Oleum and most others found in bulk` (gallons) and aerosol form - dries in 30-60 minutes. If recoated before it's dry, you trap the volatiles and get blushing, blistering, weird colors, or a soft coating that never dries properly.

Unless using oil-based stain or paste wood filler, you can do complete job - opaque, semi transparent, sunburst, whatever in 2 days and play it, put it in a case, on a guitar stand - it's dry and hard.

With many of the Colortone lacquers, Deft lacquers and a few others (recognized by "alkyd resin" and/or "naphtha" - or mineral spirits- on the MSDS) you may need to wait hours or day between coats and at LEAST a few weeks for full dry.
--One VERY light mist of lacquer over the entire body to promote adhesion. Wait 30 seconds.
--One medium/light coat of lacquer. Certainly more than a mist coat, but not nearly heavy enough to approach running.
--Wait until first coat is dry to the touch, roughly 1 minute. Blow off the body with spray gun to accelerate drying time.
--Spray a second light/medium coat. Hang up and wait for ~2 hours.
You're applying it much to heavily IMO and not allowing enough time between coats. "Dry to touch" is irrelevant - almost any lacquer will "skin off" andf FEEL dry in a few minutes. And you absolutely NEVER want to blow air across a coat that is still drying, as you will "force feed" the skin-dry feel - meaning you are deceiving yourself that it can be recoated.

Sanding sealer is applied in a single coat; sanded; and if absolutely necessary a second coat applied.

But this is only true if a "coat" does not cover completely. And it shouldn't, with pigmented sealer. Clear sealers can be applied as one light coat made up of 3 VERY light passes - then sanded, because they contain clear pigments (yes, some pigments are clear) and fillers of different sizes that seal the grain when sanded.

Pigmented primer/sealers may require two coats. If they are extremely blotchy after two coats either your technique is off or the grain should have been filled after ONE coat - and you fill it now and apply one coat of sanding sealer afterwards.

They may not cover or flow when two coats are applied - because they shouldn't. You don't WANT them to - your coverage and flow (coalescence) shouldn't occur until the THIRD color or toner coat. ANY sooner and you're "painting" - not applying lacquer.

And lacquer ain't paint. The single most common error in lacquer application is "over-application", i.e. trying to get one or two coats to cover and look smooth. It doesn't matter WHAT type of lacquer you use - full coverage/flow in one or two coats is TOO THICK.

You don't need mist coats, you don't blow air EVER, and there is no such thing as a "medium" coat. Clears are applied the same as colors and you shoud not get smooth flow/gloss until the third CLEAR coat as well! ALL lacquer coats are applied the same way except - in SOME cases, that are only recognized with experience, the last clear coat MAY be one to two "passes" heavier. But hardly ever.

And with conventional lacquers, you're done. As soon as an hour later, buff away - and if you applied everything properly it will but out smooth & consistent (and always buff using vertical cotton wheels - one CLEAN wheel per each type of stick (usually 2-3 different grits - at most - are used).

Notice I did not mention sanding - see below-

But any heavier application with earlier coats - conventional or "lacquer/enamel" blends - and you have a system doomed to early failure of some type - sticking to cases or stands, "sticky" feeling necks, inconsistent color, blistering, gloss that cannot be buffed properly....

And you never, ever sand unless it's to remove a tiny run. Sanding between coats is a sin to experienced applicators. Lacquer coats are SO thin (each coat around .001" when dry) that- unless you hosed the stuff on too heavily -

- you'll both sand between coats (which is impossible to recognize unless the types are different, as lacquer dries into ONE cohesive "coat") and you will contaminate the surface with abrasives stuck in the lacquer and micro"pebbles" of abrasives with lacquer on the surface, making buffing a difficult to impossible task.

And no "wet sanding", "surface smoothing sanding", pre buffing sanding" or whatever is required UNLESS there were errors in application - orange peel, waves, dimples and other defects - all of these are eliminated in your technique when you practice applying the ENTIRE system on scrap before touching a body or neck.

And you NEVER EVER sand between coats. If the color coats are fouled strip it, practice more and start over. Trying to sand it smooth will foul it up even more!

Work out all the issues - get your "3 pass" per coat method down to where flow/coverage just begins to start at the 3rd coat, Apply 3-6 coats of color or toner, ALL the same way and allowing the manufacturer's recommended dry time between coats. And DO NOT spray at an angle on a body laying flat - your thickness will be all over the map!

Parts need to be suspended so you spray at a 90-degree angle (and without curved "golf swings").

And to repeat - conventional lacquer and lacquer/enamel blends DO NOT CURE. They dry ONLY by evaporation.

And ONLY use the Stewmac book for general reading unless you are using Colortone products, follow recommendations for dry time (Dan calls it "cure time" - but he didn't work in the technical side of the coatings industry for 37 years, and teach union painters how to apply lacquer with HVLP units, either!) ONLY with their products, and ignore the weeks or month or whatever "cure time" is recommended unless you applied the stuff too thick and don't want to do it properly....
 

IMMusicRulz

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I am actually trying to sell my Epiphone Les Paul that I bought at a consignment store a few years ago. It was a 2000s limited edition reissue, but I didn't like the brown burst finish so I repainted it a salmon red finish.
Now that I plan on selling it, I hope the new owner will be okay with how hastily painted it is.
 

KokoTele

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If you do get orange peel that needs to be sanded out, start at a higher grit. When I started, I used a similar finishing schedule and started with 800 grit. Now if I do need to sand, I start with about 1200.

But the real answer is to work on your spray setup and technique until you get it smooth enough that you don't need to sand. It take the right combination of controlling temp and humidity and thinning the product properly for the conditions, plus gun setup.

If you look at factory nitro finishes, you'll see they are mostly not perfectly mirror smooth. There's almost always a bit of texture left in the finish when you look very closely, but it's almost irrelevant since it will continue to shrink into the wood for a while anyway.
 

TheFullMonty

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Uh-oh!

Please understand that his book is ONLY applicable to Colortone lacquers and a few others that are blends of lacquers and oil-based enamel. They are NOT conventionqal nitrocellulose or acrylic lacquers and have an extremely long DRY time.

Please note - "DRY time".

Dan talks about "cure" time - and that is completely wrong unless you are working with chemically or light reactive lacquers - which you do not find at Stewmac or most paint stores.

LACQUERS DRY ONLY BY EVAPORATION OF THE VOLATILE COMPONENTS - SOLVENTS, SURFACTANTS (FLOW INDUCERS) QAND A FEW OTHER MINOR COMPONENTS.

One properly applied coat of CONVENTIONAL lacquer - Mohawk, Valspar, Sherwin Williams, Cardinal, Rust-Oleum and most others found in bulk` (gallons) and aerosol form - dries in 30-60 minutes. If recoated before it's dry, you trap the volatiles and get blushing, blistering, weird colors, or a soft coating that never dries properly.

Unless using oil-based stain or paste wood filler, you can do complete job - opaque, semi transparent, sunburst, whatever in 2 days and play it, put it in a case, on a guitar stand - it's dry and hard.

With many of the Colortone lacquers, Deft lacquers and a few others (recognized by "alkyd resin" and/or "naphtha" - or mineral spirits- on the MSDS) you may need to wait hours or day between coats and at LEAST a few weeks for full dry.

You're applying it much to heavily IMO and not allowing enough time between coats. "Dry to touch" is irrelevant - almost any lacquer will "skin off" andf FEEL dry in a few minutes. And you absolutely NEVER want to blow air across a coat that is still drying, as you will "force feed" the skin-dry feel - meaning you are deceiving yourself that it can be recoated.

Sanding sealer is applied in a single coat; sanded; and if absolutely necessary a second coat applied.

But this is only true if a "coat" does not cover completely. And it shouldn't, with pigmented sealer. Clear sealers can be applied as one light coat made up of 3 VERY light passes - then sanded, because they contain clear pigments (yes, some pigments are clear) and fillers of different sizes that seal the grain when sanded.

Pigmented primer/sealers may require two coats. If they are extremely blotchy after two coats either your technique is off or the grain should have been filled after ONE coat - and you fill it now and apply one coat of sanding sealer afterwards.

They may not cover or flow when two coats are applied - because they shouldn't. You don't WANT them to - your coverage and flow (coalescence) shouldn't occur until the THIRD color or toner coat. ANY sooner and you're "painting" - not applying lacquer.

And lacquer ain't paint. The single most common error in lacquer application is "over-application", i.e. trying to get one or two coats to cover and look smooth. It doesn't matter WHAT type of lacquer you use - full coverage/flow in one or two coats is TOO THICK.

You don't need mist coats, you don't blow air EVER, and there is no such thing as a "medium" coat. Clears are applied the same as colors and you shoud not get smooth flow/gloss until the third CLEAR coat as well! ALL lacquer coats are applied the same way except - in SOME cases, that are only recognized with experience, the last clear coat MAY be one to two "passes" heavier. But hardly ever.

And with conventional lacquers, you're done. As soon as an hour later, buff away - and if you applied everything properly it will but out smooth & consistent (and always buff using vertical cotton wheels - one CLEAN wheel per each type of stick (usually 2-3 different grits - at most - are used).

Notice I did not mention sanding - see below-

But any heavier application with earlier coats - conventional or "lacquer/enamel" blends - and you have a system doomed to early failure of some type - sticking to cases or stands, "sticky" feeling necks, inconsistent color, blistering, gloss that cannot be buffed properly....

And you never, ever sand unless it's to remove a tiny run. Sanding between coats is a sin to experienced applicators. Lacquer coats are SO thin (each coat around .001" when dry) that- unless you hosed the stuff on too heavily -

- you'll both sand between coats (which is impossible to recognize unless the types are different, as lacquer dries into ONE cohesive "coat") and you will contaminate the surface with abrasives stuck in the lacquer and micro"pebbles" of abrasives with lacquer on the surface, making buffing a difficult to impossible task.

And no "wet sanding", "surface smoothing sanding", pre buffing sanding" or whatever is required UNLESS there were errors in application - orange peel, waves, dimples and other defects - all of these are eliminated in your technique when you practice applying the ENTIRE system on scrap before touching a body or neck.

And you NEVER EVER sand between coats. If the color coats are fouled strip it, practice more and start over. Trying to sand it smooth will foul it up even more!

Work out all the issues - get your "3 pass" per coat method down to where flow/coverage just begins to start at the 3rd coat, Apply 3-6 coats of color or toner, ALL the same way and allowing the manufacturer's recommended dry time between coats. And DO NOT spray at an angle on a body laying flat - your thickness will be all over the map!

Parts need to be suspended so you spray at a 90-degree angle (and without curved "golf swings").

And to repeat - conventional lacquer and lacquer/enamel blends DO NOT CURE. They dry ONLY by evaporation.

And ONLY use the Stewmac book for general reading unless you are using Colortone products, follow recommendations for dry time (Dan calls it "cure time" - but he didn't work in the technical side of the coatings industry for 37 years, and teach union painters how to apply lacquer with HVLP units, either!) ONLY with their products, and ignore the weeks or month or whatever "cure time" is recommended unless you applied the stuff too thick and don't want to do it properly....

Thanks so much for this info, I was hoping you would chime in on the subject. It makes perfect sense that an enamel/lacquer blend wouldn't get me what I'm looking for. With conventional lacquers, do you have a particular wet mil thickness you shoot for in one "three pass coat?" Similarly, is there an ideal dry mil thickness I should wait for before buffing? I figure estimating my dry mil thickness would be simple enough if I know my lacquer solids % and could hone a reasonably consistent spray technique. Thanks again!
 

Silverface

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Similarly, is there an ideal dry mil thickness I should wait for before buffing? I figure estimating my dry mil thickness would be simple enough if I know my lacquer solids % and could hone a reasonably consistent spray technique. Thanks again!
Unless you have and know how to use a wet film thickness gage (an inexpensive tool, but one where timing and coordination are critical), and know the equation for calculating spread rate based on theoretical film thickness/solids by volume (of he products in use) AND have the experience to know how much loss you will have based on your application method, spray equipment settings, and have both measured dry film thickness of past applications (which takes a very expensive gage fo use on non-ferrous substrates)and past experience to ensure reasonable consistency coat to coat and so on you'd be wasting your time.

The most common DIY method is to apply (after sealers, fillers etc) enough properly applied color or toner coats for consistent appearance, and 4-8 coats of properly-applied clear to have enough for a good reflective gloss and to avoid buffing burn-through.

Learning film thickness is part of intermediate application for professionals - experienced pros can judge film thickness as they've had inspectors check work enough times not to get burned - and also not to cost the company money.

It's a difficult and costly prospect for most DIY's - not measuring wet film thickness to get a feel for it, but measuring dry film thickness on wood. I still have a gage for non-ferrous surfaces I bought 25 years ago that cost around $1500.00, and they have not gotten less expensive.
 

eallen

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I picked up a conflict in your process. You said your goal was s thin sunken finish. Correct me if I am wrong, but I assume you mean sunk into the grain.Then your process stated grain filling. Unless you are using a grain filler that shrinks grain filling removes the sunken finish look. You might try partial grain fill leaving some grain exposed.
 

Silverface

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Unless you are using a grain filler that shrinks grain filling removes the sunken finish look.
Generally true - but you CAN apply solvent based paste wood filler/grain filler (I normally use Mohawk, and tint it to the "sunken" color) thinned down and get 1)a decent fill so the following lacquer coats don't disappear, and 2) Enough of a "sunken" look and feel for most purposes.

I still apply clear sanding sealer both before and after the grain filler for more consistent color. And because I generally perform at least 3-4 grain fill operations at various thicknesses depending on the job I can vary the "sinking".

I've tried the same thing with Aquqcoat and a few other waterbased fillers with less satisfactory results.

BUT - No matter what materials are used it takes 6 or more practice applications of the ENTIRE coatings system on scrap pieces of the same wood - from prep to buffing - to ensure it's going to work out.

Just jumping in on the guitar is a sure fire way to end up with a blown project.
 

Beebe

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Will a flash coat that you don't polish added as your last step do what you need?

Here is one I did with Shellac, but it should be similar with nitro. I tried to grab some pics that show the satin like finish. I think fender finishes their "closet classics" with a flash coat.

I polish by hand to the point where it's not perfect, but shiny. Then flash coat (diluted clear to about 50%) dissolves or hides any swirl left over. I spray it on pretty dry with a little higher pressure than normal from about 2ft away... Just misting it.

PXL_20220528_162058503.PORTRAIT.jpg


PXL_20220427_115308257.PORTRAIT.jpg


PXL_20220427_115340594.PORTRAIT.jpg


PXL_20220427_012610150.PORTRAIT.jpg


PXL_20220427_012651217.PORTRAIT.jpg
 

Beebe

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And here are a few things that helped me with rubbing through.

Use cork blocks and erasers as sanding blocks with sand paper not wrapped but taped to them with double sided tape.

Lubricate paper with artist oil like water washed linseed oil.

Spray coats as you are leveling. Nock down the peaks and fill the valleys as you go.

Don't just fill the grain, but level the surface with shellac/sealer/primer early on.

Edit:

I also missed the "sunken."

Here is a pine one that I did not grain fill properly. I ultimately leveled the clear, but you can still see where the color coat sunk in. Shellac.

PXL_20220627_223625521.MP.jpg


PXL_20220627_223655665.jpg


Here is a knotty pine one on which I used steel wool instead of sandpaper. Garnet Shellac over Pine Tar.

PXL_20220627_221745850.jpg


PXL_20220627_222349525.jpg
 
Last edited:

Silverface

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Then flash coat (diluted clear to about 50%) dissolves or hides any swirl left over.
Conventional lacquer thinned 50% will run right off a vertical surface - and spraying "flat" is no-go. You can't get the fan to spray evenly on the surface - closer areas get high coverage; further away is thin. It's also a great way to create "waves" in the coating.

50% thinning is almost the viscosity and solids content of blush remover. It would have to be "fogged"at a 180 degree angle far above the surface and allowed to "drift" down. If sprayed directly at any angle it would very likely create waves, variations in mil thickness and other disfigurements in the existing surface - unless applied by a VERY experienced applicator. It's not something for a beginner to try, and it's something very tough to set up as a "practice" surface.
 

CodyGleason

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3 words: Prep prep prep
Sand the wood only with flat sanding block, paying attention to how level you can get your surface. Fast forward to wetsanding, and use the same block and technique. If your surface is flat, you shouldn’t burn through the Edges. Pay attention to your technique.

There are a hundred other suggestions that could apply here for improved results, but this is the fundamental groundwork for creating a thin, beautiful finish.
 

oregomike

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Uh-oh!

Please understand that his book is ONLY applicable to Colortone lacquers and a few others that are blends of lacquers and oil-based enamel. They are NOT conventionqal nitrocellulose or acrylic lacquers and have an extremely long DRY time.

Please note - "DRY time".

Dan talks about "cure" time - and that is completely wrong unless you are working with chemically or light reactive lacquers - which you do not find at Stewmac or most paint stores.

LACQUERS DRY ONLY BY EVAPORATION OF THE VOLATILE COMPONENTS - SOLVENTS, SURFACTANTS (FLOW INDUCERS) QAND A FEW OTHER MINOR COMPONENTS.

One properly applied coat of CONVENTIONAL lacquer - Mohawk, Valspar, Sherwin Williams, Cardinal, Rust-Oleum and most others found in bulk` (gallons) and aerosol form - dries in 30-60 minutes. If recoated before it's dry, you trap the volatiles and get blushing, blistering, weird colors, or a soft coating that never dries properly.

Unless using oil-based stain or paste wood filler, you can do complete job - opaque, semi transparent, sunburst, whatever in 2 days and play it, put it in a case, on a guitar stand - it's dry and hard.

With many of the Colortone lacquers, Deft lacquers and a few others (recognized by "alkyd resin" and/or "naphtha" - or mineral spirits- on the MSDS) you may need to wait hours or day between coats and at LEAST a few weeks for full dry.

You're applying it much to heavily IMO and not allowing enough time between coats. "Dry to touch" is irrelevant - almost any lacquer will "skin off" andf FEEL dry in a few minutes. And you absolutely NEVER want to blow air across a coat that is still drying, as you will "force feed" the skin-dry feel - meaning you are deceiving yourself that it can be recoated.

Sanding sealer is applied in a single coat; sanded; and if absolutely necessary a second coat applied.

But this is only true if a "coat" does not cover completely. And it shouldn't, with pigmented sealer. Clear sealers can be applied as one light coat made up of 3 VERY light passes - then sanded, because they contain clear pigments (yes, some pigments are clear) and fillers of different sizes that seal the grain when sanded.

Pigmented primer/sealers may require two coats. If they are extremely blotchy after two coats either your technique is off or the grain should have been filled after ONE coat - and you fill it now and apply one coat of sanding sealer afterwards.

They may not cover or flow when two coats are applied - because they shouldn't. You don't WANT them to - your coverage and flow (coalescence) shouldn't occur until the THIRD color or toner coat. ANY sooner and you're "painting" - not applying lacquer.

And lacquer ain't paint. The single most common error in lacquer application is "over-application", i.e. trying to get one or two coats to cover and look smooth. It doesn't matter WHAT type of lacquer you use - full coverage/flow in one or two coats is TOO THICK.

You don't need mist coats, you don't blow air EVER, and there is no such thing as a "medium" coat. Clears are applied the same as colors and you shoud not get smooth flow/gloss until the third CLEAR coat as well! ALL lacquer coats are applied the same way except - in SOME cases, that are only recognized with experience, the last clear coat MAY be one to two "passes" heavier. But hardly ever.

And with conventional lacquers, you're done. As soon as an hour later, buff away - and if you applied everything properly it will but out smooth & consistent (and always buff using vertical cotton wheels - one CLEAN wheel per each type of stick (usually 2-3 different grits - at most - are used).

Notice I did not mention sanding - see below-

But any heavier application with earlier coats - conventional or "lacquer/enamel" blends - and you have a system doomed to early failure of some type - sticking to cases or stands, "sticky" feeling necks, inconsistent color, blistering, gloss that cannot be buffed properly....

And you never, ever sand unless it's to remove a tiny run. Sanding between coats is a sin to experienced applicators. Lacquer coats are SO thin (each coat around .001" when dry) that- unless you hosed the stuff on too heavily -

- you'll both sand between coats (which is impossible to recognize unless the types are different, as lacquer dries into ONE cohesive "coat") and you will contaminate the surface with abrasives stuck in the lacquer and micro"pebbles" of abrasives with lacquer on the surface, making buffing a difficult to impossible task.

And no "wet sanding", "surface smoothing sanding", pre buffing sanding" or whatever is required UNLESS there were errors in application - orange peel, waves, dimples and other defects - all of these are eliminated in your technique when you practice applying the ENTIRE system on scrap before touching a body or neck.

And you NEVER EVER sand between coats. If the color coats are fouled strip it, practice more and start over. Trying to sand it smooth will foul it up even more!

Work out all the issues - get your "3 pass" per coat method down to where flow/coverage just begins to start at the 3rd coat, Apply 3-6 coats of color or toner, ALL the same way and allowing the manufacturer's recommended dry time between coats. And DO NOT spray at an angle on a body laying flat - your thickness will be all over the map!

Parts need to be suspended so you spray at a 90-degree angle (and without curved "golf swings").

And to repeat - conventional lacquer and lacquer/enamel blends DO NOT CURE. They dry ONLY by evaporation.

And ONLY use the Stewmac book for general reading unless you are using Colortone products, follow recommendations for dry time (Dan calls it "cure time" - but he didn't work in the technical side of the coatings industry for 37 years, and teach union painters how to apply lacquer with HVLP units, either!) ONLY with their products, and ignore the weeks or month or whatever "cure time" is recommended unless you applied the stuff too thick and don't want to do it properly....
This is great info and I now understand where I went wrong with the couple of bodies I've painted so far. The end result was okay, but I did a lot more work than I needed to. Mainly, trying to get too much coverage in too few passes and trying to correct issues between coats.
 

jay4321

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If I can toss this small thing in based on my own experiences: if you're painting nitro for yourself, as in you don't have an impatient customer waiting on your work, spread it out over a year. I've found that the sinking lacquer and lots of small problems are minimalized if you put the bulk of the lacquer on, let a few seasons pass, and then return for final coats. I always have a few on going projects so it's easy for me to be patient.

But I do try to shoot for hyper-thin finishes and I don't do relic jobs, and I do everything by hand now, no buffers. With sanding I stick to 320 during any phase that has more lacquer shooting ahead of it, but once the very last coats are on it will see nothing but quality 600 wet/dry or finer soaked for several hours and I proceed up through 3m polishing papers with the very last steps with pure cottonballs (not "made with" 100% pure cotton, but just all pure cotton) through a couple polishing compounds.

It's tedious and sand-throughs are assured your first couple of attempts but that's really the only way to get a feel for how thin you can get away with. I recommend something like sonic blue (no clear coat) for a first attempt or two, it's pretty forgiving.

Tape off your holes when wet sanding and do those as dry as you can stand. Don't use high tack tape and stick it to your shirt first before applying to guitar.

The end results though are a finish that's pretty thin and will wear easier than normal, you will naturally relic faster. Although it's still, you know, a completed finish to start with.

I would also suggest alder for early tries, I do water-wet and sand back a couple times first. Alder doesn't need it in the way that open pore woods do but I do a little grain fill work with the clear water based stuff. There's always something with the wood, a rough spot or whatever. I just use straight lacquer to seal instead of sealer.

Once I'm at a point where I can barely get coverage and sand flat with 320 with no burn-through, even if semi-opaque in a couple spots, I will hang it and leave it. When I eventually get back to it I inspect it and see if it needs any sanding touch up, then apply several more coats. If these are clean a few weeks later I will start wet/dry and generally never sand a hard edge until I'm into the papers beyond the green. You're not going to have any issue missing some grits on the edges, you will have no problems sorting them at finer grits.

I generally avoid any sanding at all if I can during the lacquer stage, this is possible with good paint application. I'm not always perfect or in the perfect conditions to avoid contaminants but I try as best I can. I will absolutely recommend that any time you do ANY sanding, that you air blow all holes and cavities completely and use naptha to clean anything off the body. Even small contaminants can be a big headache. This is something you can't be lazy about particularly with some color finishes. Some options you will not be able to sand at all prior to clear, they simply have to be right. You really have to assume that every speck of dust and every flying bug personally hates you and your project.

To be clear this is excessive. Certainly a good, reasonably thin nitro finish can be done with an experienced person and good gun or even not that great a gun with a little patience and care. This is just what works best for me, it started with the best way to bury a headstock decal longer-term and sort of became a challenge.

This BIGGEST problem I see with thinner finishes is having too aggressive a coating schedule. If you're not in a hurry there's no rule that says you need 3x coats a day 5 days in a row or whatever a given schedule says. I like slowing that down and getting air and some time between sessions.

And then finally, on a nice warm summer day you can be out on the back porch for a few hours at the cotton stage and finally see your hard work polish up. It's very rewarding and whatever may become of the final project (I don't keep many the guitars I finish in the long run). Even if you sell it or mess something up at assembly you will always know that you did your part trying to add some magic to it.
 
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jay4321

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And as Koko Tele pointed out, factory nitro finishes aren't generally aren't perfect. Be kind to yourselves on your first couple of tries and remember it's just a guitar.
 

stratisfied

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The 20 coats of sealer and finish you propose is a long way from a thin finish. Fender experts can chime in, but the "thin finishes" on vintage guitars are more a function of the deterioration of the lacquer and the loss of volatiles contained in the finish. In all likelihood, these finishes were never wet-sanded and polished to the degree of modern finishes on day one.

The satin finishes showing off all that texturizing are just improperly applied finishes, the texture being the result of "dry-fall" or as more commonly referred to, overspray that lands in a near-dry state on the painted surface and does not flow out from having been sprayed at high temps and from too far away. You can mimic a satin or matte finish by misting the lacquer (or polyurethane for that matter) into the air over a smoothly painted gloss surface, but you wind up with that pebbly texture that is pictured from the droplets, in varying stages of drying, "peppering and cratering" the paint surface. Properly applied satin or matte lacquer flows out smoothly and dries like matte glass without the pebbly texture shown.
 
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Freeman Keller

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I have Erlewine's book on finishing, and have found it to be full of useful information.

Uh-oh!

Please understand that his book is ONLY applicable to Colortone lacquers and a few others that are blends of lacquers and oil-based enamel. They are NOT conventionqal nitrocellulose or acrylic lacquers and have an extremely long DRY time.
I don't want to get bogged down in this swamp but I will make a couple of comments.

Erlewine'd book on guitar finishing (I have the second edition) was printed at a time when both he and some other finishers were pushing so called "water born" or "waterbased" finishes. StewMac was selling something they rebranded and Dan is very specific in the demonstration of a "martin-style finish" and his recipe #13 that he is using water based finish. Dan does discuss other finishes including solvent based lacquer, but the specific step by step instructions are for the so called water born stuff.

Likewise, StewMac gives both a nitrocellulose and a waterborn lacquer schedule. I pretty much follow the nitro schedule and I have had very good results.

Second, for me a " thin, vintage-style nitro finish" would be what I would expect on a pre war Martin or maybe Gibson. The guitar body would be made from one of the tropical tone woods (all most all of which are porous) with a spruce or cedar top (which is not). I've used various pore fillers over the year and have experimented with some different water born finishes, I come back to using Zpoxy finishing resin for the filler and plain old nitrocellulose lacquer. I've used several different brands of lacquer including Cardinal, Behlens and Colortone with equally good results, I use the manufacturers recommended thinner for reducing it.

On an acoustic guitar after leveling the pore filler I'll shoot one or two coats of vinyl sealer, 10 to 15 coats of lacquer on the backs and sides, the top will get 8 to 12 with no filler. I level sand to 320 every 3 coats, the last coat is highly thinned (about 3:1). I shoot flat and don't have any problems with coverage or any of the other issues. I typically put the guitar away for a couple of weeks to dry, maybe I don't have to but it doesn't hurt.

Most of the time the final coat will require very minimal sanding and buffing - I can often start with 1200. I'm removing almost no finish - just a little bit of sludge before the buff. Here is an archtop I just finished, the mahogany back and sides got a dozen coats plus the flash, the top got six for the burst followed by three clear and the flash. I consider this a nice thin finish, the guitar does not look like it was dripped in plastic. Best part, it sounds good

IMG_7367.JPG


IMG_7369.JPG



ps - I don't do satin finishes
 
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Silverface

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Second, for me a " thin, vintage-style nitro finish" would be what I would expect on a pre war Martin or maybe Gibson
Ditto. NOT what you find on a typical Fender, for example.

The other tricky part is Stewmac has changed some of the Colortone finishes yet again - No naphtha or alkyd resin on most of the MSDS sheets, so they've cut down on the oil based enamel/nitrocellulose blends.

If you're going to use that finishing guide as a reference, like Freeman DO NOT use it as a "set of directions". Refer to it, read - but use procedures SPECIFIC to the products you are using - not some semi-generic set of directions in a dated book.

AND - please remember Mr. Erlewine still insists in his videos on referring to "cure time" for lacquer. "Cure time" DOES NOT EXIST for nitro, acrylic, nitro/acrylic blends (most commercial lacquers), alkyd/nitro blends etc ad nauseum.

"Cure time" is only applicable to lacquers that harden through chemical reaction - which most of the stuff discussed in this forum do NOT do - they dry by EVAPORATION. As a result, if they are applied to "cover". or in "flow coats (i.e. too thick) the solvents and other evaporatives can't evaporate.

They dry on top - and stay soft underneath. Or blister, bubble, wrinkle, alligator and so on.

Apply them thin - and apply practice systems until you can do the WHOLE thing where it dries hard in an hour.
Most of the time the final coat will require very minimal sanding and buffing - I can often start with 1200.
I don't sand at all. If you apply thin coats it's often faster than thicker coats - and you go straight to the buffer!
 

Silverface

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I did a lot more work than I needed to. Mainly, trying to get too much coverage in too few passes and trying to correct issues between coats.
This is the most common error - treating it like paint. And it's NOT paint.
ut I do try to shoot for hyper-thin finishes and I don't do relic jobs, and I do everything by hand now, no buffers. With sanding I stick to 320 during any phase that has more lacquer shooting ahead of it, but once the very last coats are on it will see nothing but quality 600 wet/dry or finer soaked for several hours and I proceed up through 3m polishing papers with the very last steps with pure cottonballs (not "made with" 100% pure cotton, but just all pure cotton) through a couple polishing compounds.
One other common error - sandind betwen lacquer coats - it's unecessary (lacquer is self leveling once 3-4 coats are applied - at least top the point that buffing removes all orange peel, waves etc.

All sanding with 320 or even finer between coats does is increase the chance of contamination - grittiness and/or an *uneven* - not even - finish.

An hour after the last coat is properly applied you can buff it with stuck buffing compounds using clean vertical wheels. About 10-15 minutes of buffing and you're done. Polishing papers or cotton balls (soaked in what????) are a complete waste of time, money and do more damage than good.

Apply thin coats, 30-60 minutes apart for conventional nitro, acrylic, or blended lacquers) do NO sanding between coats of after you're done with application - then buff it out.

Once you've practiced enough and have completed 5-6 projects finishing a solid guitar body takes no more than 3-4 days; 5-6 if paste wood filler is needed.

It's not that hard, but the problem is most DIY finishers are in too much of a hurry and will not take the time to practice on scrap wood FIRST. They want to learn on their first guitar body by asking what to apply first - and how; then what to do next and so on.

Practice doing it right and the final job will take LESS time.

There is absolutely NO reason to wait months or weeks between coats, or to do final buffing. And the only sanding required should be to fix small runs, if any.
 




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