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Sorry if this question has been asked, I did a quick search and didn't get the exact answer I was seeking.

Stewmac recently released their video series with the Driftwood guitar guys on how to get a professional looking finish using aerosol cans. The series was really well done, and easy to follow.

Freshly inspired to give it a try, I set out to finish my recently completed acoustic guitar using their guide (obviously skipping over the paint step). I followed the steps they laid out and was able to get a gloss finish that I'm very proud of. The obvious (to me) drawback of this process is the time it took from start to finish. Per their instructions, you should only spray up to 3 coats of lacquer per day, all with at least 1 hour in between coats, for a total of 14 coats of clear.

He talks a lot about the VOCs that are used in aerosol cans and that they need to properly gas off and that is the biggest reason why you should only do 3 coats per day. My question is this: Are the VOCs only a product of aerosol cans and if so, can the process be sped up if you elected to spray the lacquer using a HVLP system? (of course assuming you've taken all the proper safety precautions associated with spraying lacquer)

Thoughts?

No. VOCs (volatile organic chemicals) are present in all nitrocellulose lacquers, as well as most other finishes. Finishing with an HVLP system is no quicker than aerosol cans. There is no short cut to a quality finish. Did you know that lacquer continues to off-gas VOCs for several weeks?

I spray nitrocellulose lacquer 3 coats a day with light sanding every day with a HPLV sprayer. I reduce the lacquer 10 percent or so depending on conditions. Each day I lightly sand (to 320) to level before the next three coats. This is pretty much the manufacture's recommendations for most brands of lacquer (I shoot Behlens and Cardinal). I guess my feeling is that after putting so many hours into building a guitar why would I want to push the finish. I usually shoot one highly reduced flow coat at the end and wait two weeks before wet sanding and buffing.

One thing that I have not verified is that a regular poster on another forum says that he can put on the coats much more frequently and wet sand almost immediately. He says that Colortone lacquer contains naphtha in its solvent mix which makes it dry more slowly and that is why SM recommends the longer drying time. I just follow instructions. SM has their finishing schedule on their website.

That's a bummer

I did know that it will continue to gas off for several weeks. I sprayed my final coat of lacquer on my acoustic and let it set a month before coming back to it for the wet sand and buffing. The month was mostly because of a vacation though.

It is possible to apply the lacquer more quickly with a spray gun by double coating. You apply the first coat, allow it to flash off and apply a second coat behind it, and then allow them to dry. You could do three double coats in a day, sand the next morning, then apply three more double coats. Spraying lacquer with a spray gun allows you to spray a mix with more "solids" than aerosol cans usually have, so six double coats should give more build than 14 aerosol coats.
But I still wait a couple of weeks before level sanding and buffing. With finishing the phrase - "The Hurry-er I Go the Behind-er I Get" applies.

How long do you allow for the lacquer to flash off?


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I found that prep is key sealing fillng sealing and spray
you mus be careful too much thinner will break down the lacquer. Also warming it helps lower the viscosity.

I use HVLP sprayers and depending on the humidity and temp will adjust the thinner and retarder. Too much build can cause trouble. I stopped the double coating. I am doing 4 coats about 1 1/2 hr apart. I also have a spray booth so that helps with the venting. I still allow ample cure time but the biggie is that not all sand paper is the same. I switched to assilex paper and never looked back.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Matt - finishing is the longest procedure in guitar making. Unless you are shooting some kind of plastic finish, that's just the way it will be.

A hundred years ago, Model A's only took a day or two to produce. Hand painting (with brushes) on the vehicles in shellac took WEEKS.

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"Act your age, not your shoe size" - Prince

It can be as little as 5 minutes or as long as 20 minutes depending on the conditions. As John mentioned, the amount the lacquer is thinned also makes a difference.
Until you have worked with the lacquer and the spray gun you are using, single coats may be safer and will still generally build the finish quicker than aerosol cans.
You will gain more experience by rushing the finish, because by doing that you will get to do it over several times.

Sounds to me like I just rinse wash repeat what already worked. Thanks all

I was in a bind and used Mohawk pre-catalyzed lacquer in an aerosol can.
I don’t recall how many coats I used, but I was able to buff it in three days with good results.
I now use it for touch-ups.
It was expensive $25/can.

I continue to spray regular nitro with hvlp because of the cost savings, even though it’s a long process.

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wah
Wah-wah-wah-wah
Wah

I have never used the spray can stuff, but the layup schedule you quote is pretty much generic, as in works in most situations. Don't forget the environment you are spraying in is a huge influence on how many layers you can do in a day and how long between coats. Ideal conditions for me are 85+ degrees and -40% RH. If I have those conditions I do 5-6 coats a day starting at 1/2 hour between and adding 10 minutes per layer. (With Cardinal, the sealer should be sprayed and then recoated with a second coat within 15 minutes. I give a total of two sealer coats, with the lacquer going on 15 minutes after the second coat.) I do 5-6 coats on the second day, level sand the day after. Then level sand at a week. Let it rest for 2-3 weeks, do a 400 grit level sand then on up to 800 grit and buff. Conversely, you will need to add time between coats and less coats a day if conditions are poor. As in -70 degress and move than 49% RH. I use Cardinal luthierLac

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Joe Beaver
Maker of Sawdust

I have found that if you lay too much on too fast you will have adhesion issues. The VOC were changed and it takes about 2 hr to gas off. Since I went to this schedule I have much better adhesion and finishes level better. I used to be of the school pile on and take down. I changed that opinion . I no longer lay out .016 in thick I do about .008 to .010 level then shoot 2 coats and a finale 3rd with a touch more thinner and retarded usually you can get on it in a week or so
I was using Mohawk but now use the same laqguer Martin is using.
AZKO martin is also using sherwinn williams .

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Has there been an article or post written that I can read that talks about how to deal with varying weather conditions when spraying? My current setup is just one of those Wagner pop up spray booth tents, setup inside my garage. I keep the garage door open, turn on a box fan to blow the over spray, and I have one of those jet dust extractors that I turn on (got it for free, not convinced it does anything ever lol).

Matt,
The first place to look is on the finish manufactories web site. I do that before I buy the product. Besides layup you will need to know what pore filler and Sealer to use and how to use it. The manufacturers typically have Product safety sheets and info on using the product, including layup info. The Stewmac site should have some info on usage. I know Cardinal does for their luthierLac.

Another good source of infor is Luthier/Finisher Extraordinaire, Ron Howard. I haven't visited his site in a while, but he did have an extensive library there on how to finish a guitar. And here on the forum. If you are not sure ask the question. There is a wealth of knowledge here.

Good luck.

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Joe Beaver
Maker of Sawdust

I think the books and instructional videos from Jeff Jewitt are great. The best guitar-specific information from Jeff is available on the O'Brien Guitars website. His lacquer finishing video course costs a little money, but I think it is worth every penny.

Were you referring to Brian Howard (not Ron)?

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Steve Smith
"Music is what feelings sound like"

Joe's been watching to many "Happy Days" reruns.

Steve wrote:
Were you referring to Brian Howard (not Ron)?[/quote]

Yes, Brian Howard. Definitely too much happy days.

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Joe Beaver
Maker of Sawdust