Official Luthiers Forum!

I just started finishing last year. I've been able to get a pro finish on several guitars. I started out with a Wagner HVLP rig and a few months later invested in a compressor, guns, etc. Some people dread the finishing process. I almost can't wait to get to it. I believe the reason for that is because of Nitro. It takes a little bit of learning on the front end but once you figure out what works for you, it's a very convenient finish that yields professional results without too much hassle. And obviously it doesn't take long at all to learn as all I had ever done prior to that was Minwax poly from the can with a brush. Never on a guitar, just on random projects.

I made a little booth with a box fan and furnace filter at the end of a funnel type structure. It works great. I was skeptical about the idea of it at first but after reading a great article by Michael Dresner (renowned finisher) in one of the wood magazines, I figured it must be safe.

_________________
"I'm not going to say that perfection has never been achieved. However, if it has, it probably went unnoticed due to it's lack of character."

Yeah, you and me both......I've got three coming to finish stage in the next few weeks, so i plan to spray, not with nitro, but pre-catalysed lacquer. I reckon, from past experience, that I can coat the three in about 15 minutes, if I'm slow. An hour later, again, etc, etc...One week cure, level, then 3-4 more coats, and a 3-4 week cure and buff out. I think my first--french polished--probably took 2-3 weeks of the same time investment.

PLUS----- BIG, BIG, BIG PLUS------ that's what most customers want. OK, I'll do it, and take the time to learn to do it properly.

For better or worse, the big makers have taught folks that the more shiny a guitar is, the higher the quality. It'll be a rare buyer that says "I don't care what the finish is, as long as it sounds great. " They all(or mostly all) want the mirror finish, so they get it.....

What is the advantage of pre-catalyzed lacquer?

Chuck

_________________
_________________

Todd has it dead nuts on about the reasons to sand vinyl sealer...and also for sanding between coats..

also, if you are doing a thicker finish schedule (for backs and sides let's say) it is 'wise' to wait a week between 5 coat sessions...this means a scuffing of the finish is required

as far as burn in, when I have doubts because of the time passed between coats, I will spray the first new coat with about 10% more reducer for that coat only...and will also spray that coat thinner than I normally would...the extra reducer softens up the previous coats...

Back to the original query, it is all in customer attitudes.

When people see a lighter hand finish, they think one of two things. Either 1) Amateur/weekend warrior, even if said hand finish is harder/better/more impressive than a spray, or 2) cheap guitar - many manufacturers use a non-gloss on cheaper guitars to lower the price point, and anything not shiny tends to give that impression.

Whether there is any real veracity to these notions is irrelevant, but if someone wants to explore an alternative finish, they need to spend some time to explain why they do it and why it creates a superior product. If a major builder can successfully make his case, then the rules of the game can change. Until then, you need shiny and hard to look truly professional.

+2 on Todd's scuffing points. Consider the benefit of knocking debris off the surface that would just get buried in finish and become much harder or impossible to remove once you have established your final film thickness. That and the piece of mind from a mechanical "tooth" for the following coats to grab.

If I were finishing my own guitars without the prior experience with auto and industrial finishes, I would certainly choose nitro lacquer. So forgiving, easy to learn and aside from the solvent content, relatively safe on your body with the proper safety equip.

_________________
jw ( o)===:::

Glen H wrote:
"I use nitro because I don't like blue guitars. Not to mention it is so easy and quick to apply. Full burn in. Finish can be thin. Not as "toxic" as some other finishes."

I don't know where you get the idea that nitro is not 'toxic'. From what I've been told, the least toxic stuff in lacquer thinner is toluene, and that's toxic at a concentration of 1/10 of what you can smell. The esters and ketones that are actually dissolving the nitrocellulose are worse. That's one reason why most locales have pretty strict regulations regarding spraying the stuff. Sure, most of us work under the radar, but that's to our cost. After years of spraying nitro with inadequate facilities, I'm so sensitive that I can't open a can without becoming ill. Go scope out the regs some time. As far as I can see, the _only_ advantage of nitro is the short term one of speed.

Funky Kikuchiyo wrote:
"When people see a lighter hand finish, they think one of two things. Either 1) Amateur/weekend warrior, even if said hand finish is harder/better/more impressive than a spray, or 2) cheap guitar - many manufacturers use a non-gloss on cheaper guitars to lower the price point, and anything not shiny tends to give that impression."

The manufacturers took up nitro because you can build a level finish that has minimal shrinkage fairly quickly and reliably, and, in a manufacturing situation, it's not overly expensive to meet safety and environmental regs. That surface is impressive if you don't think too much about it: many of the manufacturers use much more finish than I'd want to put on a guitar, and, as has been said, it's the thickness of the film that ultimately counts most. Over time that slick look has become 'the standard', and now we're expected to meet it (admittedly, there's a bit more to it than that, but I don't have time right now...).

It's possible, if more difficult, to match that surface with almost any material/technique, if you want to take the time. Probably the most work is oil/resin varnish. One reason is the longer time to re-coat, but, more importantly, it's the nature of a reactive finish as opposed to a solvent release one. Once the solvent has gone out of the lacquer, it's not going to shrink much for a while (until the instability of the finish itself takes over). Varnish can spend several months curing, and shrinks the whole time. Although I've found that the number of man-hours it takes to get a good finish is pretty much the same no matter what material I use (with the exception of French polish) there's no getting around the long lead time with varnish.

In return, varnish offers more 'depth' than most finishes, and can be both flexible and tough: that is, it can dent easily, but be hard to scratch, and can wear very well. The flexibility may well be _better_ for tone in the long run. Because of the chemistry involved, good varnish is very solvent resistant, and much more stable once cured than nitro ever dreamed of being. In that respect it approaches old (but not new) shellac, which gets better with age, as opposed to nitro, which gets worse.

The chemistry is, of course, why varnish does not 'burn in' well, and that's one of the biggest drawbacks, aside from the shrinkage.

At any rate, if you think about what the finish is there for, we should not have to apologize for thin finishes that allow the grain of the wood to show through. The fact that we do is a marketing issue: we have not educated the customers about the many costs that come with a slick finish, and we're paying for it.

A few years ago I built a 19 th century Terz Guitar. It was a development model and therefore I felt free to use whatever finishing method that i deemed appropriate. In actual fact I decided to do a scraper finish on the whole body - soundboard and the Maple Back/Sides, pretty much using the methods that good Violin makers use. I messed about with the actual finish a few times but ended up brushing some shellac/spirit varnish mix on it. That turned out fine but still appeared to be too glossy. I tried wirewool to dull the gloss. Of course it worked but left micro scratches in the surface. I then became a little fed up of the whole thing and decided that I would wax on top of whatever I had. You could still see some of the tiny scratches but the whole feel of the finish was very attractive with the wax. Probably the nicest finish that I've ever done. I sold the instrument to a friend and occasionally still see the Guitar. The finish has shrunk and now you can see undulations to the figure of the Maple on the Back/Sides. The soundboard has that reeded appearance and you can feel the slight texture. I can't but help feeling how cold and utterly boring highly flat, glass like Guitar surfaces have become. I don't think you will win many people over using my approach though. For one thing, flat and high gloss looks impressive - at least it does for a few seconds. Pretty much like looking at a Steinway Piano. Looks incredibly impressive but becomes awfully uninteresting very quickly. . . but it's that first look that really impresses people. They equate it with quality. They equate texture and subtle undulations with lack of skill. The violin folk have been educated into seeing the Cremonese finish as the pinnacle. The factory flat glossy Violin is seen as the cheap, inferior alternative. You could almost say it's the polar opposite of the approach to Guitar making. Years ago, young and naive I used to think that Violin makers were very good craftsmen but were terrible at varnishing.

Thanks, Michael: somebody gets it...

Several years ago I had a student who was a study in ADHD: he wanted to do all sorts of fancy stuff, but couldn't seem to stick with it long enough to get it right. When he made mistakes they never got fixed right, so the guitar ended up pretty rough around the edges in some ways. He was, however, very good with lacquer, having made a living painting motorcycles at one point. He took the guitar home, got himself a case of rattle cans from Stew-Mac, and put on the best lacquer job I've ever seen. Up to that point I used to think that you couldn't hide anything under a clear finish: now I'm not so sure. The mistakes were still there, of course, if you looked for them, but very few people ever got past that surface.

To me, the look of the violin is the proper 'craft' standard: asymmetry, a few tool marks, and a scraped rather than sanded surface, all show the hand of the maker. It's NOT 'sloppy': I'd love to make 'mistakes' that were as good as Strad's, but it's not the totally uniform 'factory' look either. A fine violin is a work of art; Martin and Taylor are factory productions. Why in the world have we allowed ourselves to be tied to the factory standard?

Of course, in the highest craft traditions a fine finish counts for a lot: Strad is still known for his varnish, after all. But the best evidence is that he didn't rub them out, and was not overly concerned with shrinkage either. The guitars I saw in Spain in the early '70s, when French polish was still the norm, were not totally filled: they were only just starting to fall into that trap then. Shrinkage that left the grain, and the structure of the rosette, plainly visible, was considered a sign that the finish was not so thick as to impede the sound. In some cases they'd leave the shops pretty 'dry', and get the polish built up over the years as they came in for adjustments and repairs. Even the pianos I've seen that dated from before the introduction of nitro didn't have 'piano' finishes as we think of them.

Several years ago there was an exhibit of guitars as works of art in Boston. It was pretty easy to see when Martin switched over to nitro: the ones made just after the change had finishes that were in much worse shape than the ones from before the switch. That's not that long ago. Why would you want to use a finish that doesn't hold up as long as your guitar? Or, if you like that look on a new instrument, why not just accept the fact that it will need to be renewed every once in a while? This business of treating a modern mass produced guitar with a nitro finish as if it was a 300 year old varnished violin is absurd: nitro is an industrial coating, Strad's varnish was part of the artistic intent.

Sorry for the rant. I understand that 'slick' is the accepted standard for guitars these days, and put in the work to meet it as best I can, given the limitations of the finish, but it ticks me off. Factories live by that sort of unimaginative 'flawlessness', but it's a luxury, and a very expensive one, for a hand craftsman. By holding us to their standards, and not just in finish, they distract the buying public from the things that we can do that they can't. We ought to be trying to get them to play by OUR rules.

Prreach it Al! Can I get a witness?

_________________
Pat

Amen!

_________________
A man hears what he wants to hear, and disreguards the rest. Paul Simon

I would just like to point out a few things....First, shellac and varnish were the industrial finishes of their day.The old timers used them because that's what there was and until something better came along.....well nitro was the first of those something betters. That has been supplanted by polyester based coatings like amino alkyd conversion varnishes, pure polyester in a UV cured form And many other acrylics and polymers like urethanes etc..

Second, they call it sanding sealer for a reason. It is generally meant to be sanded prior to the top coat application. Sometimes the coating needs that mechanical anchor, nitro doesn't readily melt into vinyl all that well. The vinyl sealer provides a bit of float between the wood and the acrylics as well as sealing the wood and providing a base for the coating. The float is needed to help prevent cracking and crazing in modified lacquers that do not expand and contract as well so they can keep pace with movements in the wood.

Third, Inter-coat sanding (Beyond sanding the sealer or leveling shaders) is really only useful if you want an off the gun finish. If you are going to level sand and buff at the end it is a waste of time. You will never save all the time on the final level sand that you put into the sanding and then cleaning in between coats so you will spend more time doing this than is actually needed. Then there is the cost of the extra abrasives and the extra material you always wind up putting down because you are sanding 30% of each coat back off rather than 15% of the total film at the end. And in the end there is no visual or functional difference if you do all your sanding at the end. It is a common problem in woodworking that people start sanding too early, sand way too often and sand too much.

Well that's my two cents for the day, now I'm broke again.

_________________
Brian

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

https://www.howardguitarsdelaware.com/

I spray a few coats then sand level with 220, spray a few more, sand level with 1500.

If I waited until the end and sanded with 1500 it would take a LOT longer than sanding once with 220 and once with 1500.

If I waited until the end and sanded with 220 then 1500 I would likely sand through in spots.

That's my argument for intercoat sanding.

The rest doesn't bother me, I like shiny hard finishes as well, as long as they're thin enough. My customers don't mind the reedy look that my soundboard gets because I've explained to them that the sound they're hearing is partially due to the thin finish, and they "get" it and explain it to their friends when they ask.

_________________
Old growth, shmold growth!

My sanding schedule for buff out stats at 400 as well. Then I use every grit up through 1200 and then buff. This really does not change much with sanding between coats.like Filippo said, maybe start at 600. So I maybe save 10 minutes there but spent an hour or more sanding between coats and cleaning the surface for the next coat.

_________________
Brian

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

https://www.howardguitarsdelaware.com/

I find it quick and easy to sand the first time with 220. The next round of spraying levels out all the scratches, and if I get a good flow leaves it practically ready to buff. So I start with 1500 and that's all I need and it doesn't take super long.

My schedule is based on the fact that I used to use rattle cans (15 years ago) which didn't build very fast, and so I would sand through frequently even if I started at 600 grit, so I started to just go for the 1500.

I started doing my first level sanding with 220 after watching Bob Benedetto's archtop video.

Finishing is not my strong point, but why the sarcasm?

_________________
Old growth, shmold growth!

Great thread.

So Todd, you're shooting un-thinned. Four coats, sand, four more on top, five on back/sides.

Filippo, you're shooting six straight. Also un-thinned, right?

I love this forum! The articles complaining about customer desire for flawless shiny guitars made me feel less alone in the world.
I am an amatuer repairman, but my friends and I play our guitars a lot at rough parties. What I have learned how to do in finishing is this: I can take an old nitro guitar that has been to five hundred rough parties plus been horribly broken and repaired wrong, and rescue the situation so that it plays right and only looks like an old guitar that has been to five hundred parties. We all love that look. It's easy to get with nitro and transparent dyes. I love the deep look of a colored dye over a slightly different color layer. Looks like beautiful old guitar to me.
I've never tried, but I suspect that it would be much harder to do this kind of finish repair with modern cross-linked finishes. I've used a lot of good superglue in model airplanes but not much on guitars. I would be happy to hear from someone that repairing modern finishes is not that hard. I'm talking about stuff like taking a broken headstock fixed with wierd color wood splints, ugly amateur repairs, and making them so it takes a real hard look to see where it was broken, while leaving the guitar looking loved and used hard.

I spray my finishes with a brush.


Sent from my iPhone using Tapatalk 2

_________________
http://www.CostaGuitars.com
PMoMC

What size fluid nozzle and air cap on that brush?

_________________
jw ( o)===:::

It's a 2 inch nozzle with several thousand tips. It leaves a rough finish but I don't mind a bit of sanding.


Sent from my iPhone using Tapatalk 2

_________________
http://www.CostaGuitars.com
PMoMC

That's a Super High Volume medium pressure setup I believe.

_________________
jw ( o)===:::

Cool. Thanks, Todd. I'm spraying Cardinal, but I'm going to try this on the guitar I'll be finishing in the next week or two.

Spraying finishes with a brush has definite advantages. It's cheap. Don't take up much room. Zero maintenance. If you break or lose one of those tips it doesn't really matter. You can shellac your fingernails with one. I'm sure there are numerous other advantages.

Simple dings and chips get the CA fill. You can pad it onto larger areas. But for a headstock like you mention I usually will refinish the neck with a two part urethane. This is almost mandatory if you need any color other than clear for the repair.

_________________
Brian

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

https://www.howardguitarsdelaware.com/

That is correct. That must be why your finishes are so good!

_________________
http://www.CostaGuitars.com
PMoMC