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Idle curiosity only, but after spraying and level sanding... and spraying and level sanding... and spraying and level sanding... and sanding and buffing... I got to thinking that I put nearly a third of my time into the finish.

I just can’t imagine a factory spending so many man hours on that. And yet many factory finishes are near perfect. At least on major name makers. I know they use UV cured poly to speed up cure time, but that doesn’t address all the hand work involved.

How do they do it?


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I recently took a tour of the nearby Paul Reid Smith shop and it turns out they have just one guy who sprays every guitar (a lot of theirs are made in Asia, so not "every" guitar). I bet he makes it easy on the guys with the power sanders.

Ed

Machines and lots of practice.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

That's what 50% of the price of a PRS or Gibby is.... the finish. There are no shortcuts beyond what can be done with UV cured coatings. You can cut out the dry time but the labor it takes remains the same.

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Brian

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

https://www.howardguitarsdelaware.com/

LOL! I know exactly what you mean. I have to tell people that it takes me about two weeks to construct a guitar and two months to finish it. It's what I actually hate about guitar building and can totally understand why some builders contract that out. If I could sell guitars at such high prices I'd probably do the same.

It is rewarding when it's done right but in every single case I always find flaws in my finish work and it drives me nuts. You spend 2 months trying to perfect a finish and a $500 Yamaha looks better. Of course I know there is more to it then that, we strive for acoustically thin films but still...

And don't even get me started on, when you get the finish just right then ding it doing the final set up!

The differences between small shop and factory building is something that is discussed regularly in the shop where I usually work, and the consensus is that guitar factories refine finish operations such that they become routine, low-risk events which can be accomplished as quickly as possible. This is the case for every step of the building process, as factory builders usually see labor as a cost which may be reducible by improving process, controlling environment, automation, or outsourcing. Factory builders have problems, but those generally are related to what happens before and after their instruments are built, while most problems small shop builders deal with are related to the actual process of building of their instruments.

Hobby and small shop builders have far fewer finish cycles in which to work through improvements to the finishing task, but you may still be able to make some changes to reduce labor:

1. Consider eliminating those 2-3 additional cycles of level sanding, and do just one after all coats are applied. Standard instrument lacquer does not need sanding between coats to encourage burn-in, and some other finishes (e.g., Enduro-Var; some polyurethanes) have 'no-sand' windows within which additional coats may be applied without sanding. See comments below if your sanding is primarily related to surface quality flaws due to environmental or application method issues.

2. Research the finish you are using and determine whether alternative application schedules are working for other users (understand that finish manufacturers do a lot of testing and know their product well - make sure your alternate finish schedule is not just some untested piece of Internet 'whizdumb')

3. Where temperature, humidity, dust, or other environmental factor is adding labor to the process (e.g., sanding out dust, pollen, etc.), control application environment

4. Where your equipment is interfering with your ability to apply a smooth, consistent finish, consider upgrading gun, air source, etc., or if hand-applying, consider faster, more consistent spray application.

5. Outsource your finishing to eliminate the labor and material cost variables, and use those labor hours on another instrument or to add value elsewhere.

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We have become a civilization that elevates idiots, prostitutes, and clowns. Am I still to defend it? Yes, for its principles. Yes, for what it was. Yes, for what it still may be.

-Mark Helprin, The Oceans and the Stars: A Sea Story, A War Story, A Love Story (A Novel)

What Brian said. Taylor has a robotic buffer and I think Martin is using one now too. That cuts down on one aspect of the finishing labor. Taylor also uses a robotic system to apply the finish using an electrostatic transfer that improves the efficiency of the material application. Even with those leaps in innovation, the guitars still have to be leveled with a human and that's one aspect of finishing that just takes time/labor. You can't rush the love there.

For the small or independent guitar builder, finishing can often derail the whole experience. The sum of not getting enough finishing experience (time between builds) to materials being used beyond proper use dates to the expense of all the necessary equipment to safely and efficiently do the finish can discourage even the most skilled craft person but there are still may that can overcome those challenges.


Until the market dictates that flat and shiny, full pore filled guitars are no longer the standard, it's a challenge that will test guitar builders again and again.

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jw ( o)===:::

It's either time or money, just like everything else.

Taylors finishes used to be horrifically thick, up to .009. But they were glass smooth.
SCGC finishes are fairly thin. Incomplete pore fills and laquer pops are pretty normal.

I agree that it takes almost as long to finish as it does to build. With the drying times, longer.

T

Threads like this are so helpful. It soothes the message of "this takes way too long, I must be doing something wrong" that is on constant loop in my head. There are no shortcuts, stick with it!

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Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

Back in the Model T days it was no different. The car was made in days, the black shellac? WEEKS.

Also, the popularity of flat finishes on guitars sped up finishing times - and builders were grateful.

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

Martin uses a robotic spray booth
filling is done by hand
then the sealer is applier like the finish in the booth
after cure the finish is level sanded by hand
they have this mastered and can do 4 to 6 guitars per hr.
they also have a clean room that can cure finish in a few days
the auto buffers work will and there are 2 on line.
some hand buffing is still done but the man hours is down compared to what is was 20 yrs ago.

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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

But the actual hours needed to finish remain virtually unchanged. Buffing takes a few hours no matter if it is done by a robot or a man.....

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Brian

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

https://www.howardguitarsdelaware.com/

I seen a few videos where once the finish is sprayed (and it is usually polyurethane or 2K finish of some kind) they use an air sander with 600 grit and just spend probably maybe 10 minutes to sand the ENTIRE finish. They do this DRY, no wet sanding at all (seems to me most manufacturers do not wet sand, the reasoning being it makes a huge mess and can ruin woods). Then they use a big buffer with a very aggressive compound followed by a fine one. Taylor uses a robot for the whole operation. Bridge is always glued in after finishing, not before.

For small builders I would make the following recommendation:

1. Epoxy fill everything. This takes care of all grain, pores, defects, etc. that can come back and bite you later on. Epoxy does not shrink as it cures so you have a stable platform in which to work.
Something BIG like swamp ash maybe use a colored paste filler before epoxy.
2. If using lacquer, spray the necessary number of coats. DO NOT sand between coats unless you have something major happen. It wouldn't do you much good anyways because the finish just burns in and undo all your sanding. If using 2K finish, follow its recoat instruction but I found (at least the ones I have to work with) you wait for the finish to get sorta sticky when touched, then you recoat. Do it all in one go, spray a coat, wait 15 minutes, spray another coat, wait 15 minutes, until you built up the level you wish to have. Then STOP, clean your gun, no more coats. Let cure for a couple of days then go onto buffing.
3. Sand DRY with something like 600 or 800 grit paper, use a good no load paper and make sure the finish is completely cured. Any uncured finish will load your paper up badly. If you are daring or adventurous use a power sander for this step, this speeds things up but if your finish thickness is low you run the risk of going through. Perhaps this is why people like Fender have such thick finish.
4. Use a cut compound followed by a finish compound. Menzerna P204 followed by GW16 or even P175 will work (whichever one you can get cheaply in your area, P175 costs an arm and a leg where I'm at).

I've only used nitrocellulose before and I'd say it takes me about a day of labor to do, but it really takes more than 2 months because the finish takes so long to cure. 2K will reduce this time to a week.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

If I understand the OP's ask, there were two asks - one explicit and one implied: how do factories accomplish finishing at an affordable cost, and how may a small shop reduce labor hours related to finishing? The first ask was well covered by most respondents, and the second touched on lightly. Beyond a search back through old threads on finish application schedules or Mr. Proulx's and a few other's excellent threads here and on the MIMF re: catalyzed and UV cure polyesters, the OP might consider opening a thread on optimizing finish schedule and process.

A few calendar time data points:

- For instrument lacquers (which I understand may not be available in some countries), drying time runs 10 days in our forced air drying box or three weeks in still, shop temp & RH air. With pore filling (either paste wood or epoxy - we do both), finish application, and drying time (shellac and nitrocellulose lacquer dry; poly, oil varnishes, etc. cure), we can run as little as 2.5 weeks to 'finish complete' or as much as a month in terms of calendar time (assuming no interruptions, and there are ALWAYS interruptions when a shop does repair work).

- We consume about the same amount of calendar time on an Enduro-Var finish as on lacquer, due to the 21 day cure cycle

- Our average labor on finishing is about 1/3 of what averages out to be about 60-70 hours of total building time.

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We have become a civilization that elevates idiots, prostitutes, and clowns. Am I still to defend it? Yes, for its principles. Yes, for what it was. Yes, for what it still may be.

-Mark Helprin, The Oceans and the Stars: A Sea Story, A War Story, A Love Story (A Novel)

There’s a pretty good chance that people in factories are quite a bit better at level sanding than your average home builder just due to experience. If level sanding and buffing was your only job, you’d likely get better at it pretty fast.

As Tai mentioned, using a power sander with dry paper will cut down on your sanding time a LOT, like a lot a lot, and will also yield a finish that buffs out with much less effort and time. As well, the buffing machines in a factory will quickly reveal how rinky dink the SM/Caldwell buffers that most of us have access to are.

Back when I did that a lot, level sanding a box and buffing it out perfect in 1.5-2hrs was about right.

The finish will likely be laid on better in the first place too.

So, more experience and better tools will go a long way. That being said, gloss finishes are a PITA no matter how good you are. Unless you contract out:)

I lucked out... so far the few customers I have who commissioned me for a guitar did NOT want a glossy guitar. They wanted satin finish. Makes my job 1000 times easier.

I am going to guess, a lot of low quality, poor sounding (but good looking) guitars have VERY glossy and bulletproof finish. So customers who would want a hand built guitar simply did not want a shiny guitar. Every Cort guitars I have seen are incredibly shiny, like polished polyester.

Every hand built guitars I have seen so far did not have the high gloss bullet proof finish. In fact all the very glossy guitars I have seen have been rather bad sounding, poorly made, essentially mass produced. The Martins I have seen have a shiny finish, but you could tell the gloss on a Martin is not the same level of gloss as say a Sigma (a very badly made Martin clone, made in China, costs only around 700 dollars). In fact you could tell a Martin had a real organic looking finish.

I saw a hand made guitar, where the rosette was basically prints of some classic arts. He glued it in and filled it with finish. Problem is he used German spruce and it yellowed like you wouldn't believe.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Another thing big factories have at their disposal is process engineers, whose job it is to hone the process for the utmost speed and lowest reject rate. It can be applied to finishing or any other manufacturing process. If they need to put out a product every minute to meet quota, and one step of the process takes 3 minutes, then they might either break the process step down into 3 steps so that each step is only a minute, or the line might branch out to 3 parallel lines so that 3 stations are doing the 3 minute step to turn it into a one minute step, in a sense. The term line balance is used so that the 3 minute step doesn't make the next step wait 3 minutes between products. The end result in a well-balanced line is that no station is empty, every station on the line has something to work on, there are no backups, and product comes out the back end at a steady pace. It's really something to see when it all clicks.

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formerly known around here as burbank
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http://www.patfosterguitars.com

The idea of a well-engineered factory process always makes me think of this music from my misspent youth:

https://www.youtube.com/watch?v=w3FCRr3t9WU

It is time consuming.
I just checked back and it's taken me 4 weeks exactly to get from my first coat of epoxy through to buffing 2 guitars in gloss (Enduro Var)
Just glued on the bridges and one of the necks today, and for me that's good going.
Panic's been setting in with the event coming up, so it's been up to 10/11 hrs a day most days, with just a few necessary days off.
So maybe a week to 10 days to do the rest (basically level FB, fretting, tuners, nuts and saddles. then set-up) I might just make this for the exhibition!

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Good luck!

The first time I heard of spraying all the (lacquer) coats without leveling between was from Filippo back in the day. I love the idea, just not sure how to gauge where to drop in order to get that .003 film thickness. Gauging that film thickness before scraping off a chip of the final product to measure remains a mystery to me.


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I sand between each cross coat of lacquer so I don't apply more finish than I need (satin finishes). If I skipped the intermediate sanding, I wouldn't know when I'd applied more lacquer than I needed. Sure does eat time, but the process doesn't get out of hand for me. Once a sanding shows no shiny spots, I know I've got a filled and leveled surface, and the next coat is the last coat. Worked for me so far and satin finishes don't need buffing.

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Peter Havriluk

I often wonder if some of the overseas factory perhaps do need all the man hours, but labor is so cheap they just get an army of workers to each do a guitar. So a guitar may take the normal amount of man hours (perhaps a process engineer would reduce this too) but since 100 people are doing it at the same time, they can output a lot.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Pros tend to be very good at consistent application of material, getting a perfect wet coat every time. This wet coat is of predictable thickness, and if the solids ratio of the thinned finish is known, it is a straightforward process to calculate the required number of wet coats to build to a specific final dry film thickness.

When I started spraying, one of the early exercises was making up two dozen 3mm x 15" x 5" meranti marine plywood test panels with scrap spruce handles attached and filled with epoxy pore filler (scrap ply from a boat-building project - nothing went to waste). I sprayed these panels in vertical orientation with thinned instrument lacquer of known mix ratio, then measure the wet film thickness on each panel using a wet mil gauge (see link below). A few panels were intentionally sprayed very wet, and a few done using a double-coat method that builds finish very quickly. The applied film thickness was the measurement of the last wet tooth plus 0.5 mil (0.001").

Mohawk Classic Instrument Lacquer (solids content): 13% by volume

Thinning: 70/30 by volume (solids 9.1% after thinning)

Wet film thickness (desired): 4.5 mil max (yields .41 mil dry film thickness per wet coat)

Desired dry film thickness after 21 day drying cycle: 0.0035" top; 0.004" sides/back/neck

Number of wet coats to be applied: 8 to top; 9 to back, sides, and neck (sealer coat adds remaining thickness)

Sanding removes between 0.5 and 0.75 mil, so final thickness after sanding and buffing is targeted at .003" top and .004" sides/back/neck.

https://www.amazon.com/82-479-Film-Gaug ... B01BM7MU02

_________________
We have become a civilization that elevates idiots, prostitutes, and clowns. Am I still to defend it? Yes, for its principles. Yes, for what it was. Yes, for what it still may be.

-Mark Helprin, The Oceans and the Stars: A Sea Story, A War Story, A Love Story (A Novel)

this coming guitar is going to be my first 2K finish, and my usual method is going to have to change to maintain the same finish thickness. 2K as far as I know have a huge amount of solid, like at least 50% by volume, since once the solvent flash off it just chemically cures.

I did a single session of 3 coats, 15 minutes between coats and I'm building the same finish thickness as 3 separate sessions (a day apart), 3 coats per session, 15 minutes between coats with nitrocellulose.

It's not polyester/epoxy thick, but I gotta watch it or else I can end up building too thick of a finish.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com