Getting A Good Lacquer Finish

[justinj]

Just glued the neck on my first mandolin build, so I'm getting dangerously close to applying a finish. I've decided to just spray a lacquer finish instead of going through the whole varnish/french polish rigmarole.

I did a search of the forum and could only find disparate snippets of info on the subject, but basically, what steps do I need to take to get from in-the-white to a nice finished mandolin using lacquer?
I have access to spray equipment (although not a whole lot of experience/skill), so I won't have to resort to aerosols.
Any advice would be much appreciated.

[sunburst]

Practice on scrap.
Sand some scrap wood exactly like your mandolin and go through the finish process to see what problems you have (hopefully none, possibly quite a few).
If you are going to apply stain (dye) decide how you will do that (rubbed on bare wood, sprayed on bare wood, sprayed over sealer, etc.)
You'll want a sealer of some sort to improve adhesion of the lacquer. I use blonde shellac, many manufacturers of lacquer recommend vinyl sealer (and usually their own brand), but whatever, apply the sealer and follow the directions for timing if it is a vinyl sealer (the amount of time between vinyl sealer and first coat of lacquer can be critical to good adhesion). Now, your surface is prepared and the process of applying the lacquer begins.
Simply, put, spray two or three coats, wait overnight, sand, repeat. The sanding of the first spray or two needs to be very light; just a brush over withe sandpaper to knock off the roughness of the surface. As you build film thickness, eventually you will be able to completely level sand the whole surface. Spray once more and let the lacquer cure for buffing. A week is OK, two weeks is better, longer may or may not be better still.

[Marty Jacobson]

Amen to everything John said... also, resist the temptation to re-spray too soon. Leave it at least an hour or so before spraying the next coat. Lacquer is pretty forgiving because it "shrink-wraps" dramatically. A drip or run which may look huge when you are spraying may almost completely blend in once it has set a bit. But the closer together the coats are (meaning, only minutes apart), the more likely they are to add up and cause problems. Recoating too soon, too thick can cause very bad orange peel, though that's a bigger problem with sprayed shellac than lacquer.

Buy an HVLP rig and learn how to use it! I have used both conventional and true-turbine-based HVLP extensively, and my DeVilbiss conventional guns just sit there as pretty decorations. HVLP is the way to go. I can spray strong tinted lacquer less than a foot away from other instruments.. no overspray or bounce-back. Less grit on the floor, less "sand" under the fretboard extension, just better, IMO.

[sunburst]

Buy an HVLP rig and learn how to use it! I have used both conventional and true-turbine-based HVLP extensively, and my DeVilbiss conventional guns just sit there as pretty decorations. HVLP is the way to go.

Here's a disagreement. I've used both, HVLP and conventional, and I spray with conventional guns. Why? It's what I have, it's what I'm used too, and it works just fine. The big advantage to HVLP is material saving and less overspray. The quality of the surface is up to the operator, thought it is dependent on having a good tip/nozzle combination, but that can be had with either system. With the amount of material (lacquer, etc.)that I spray, I would never in my lifetime save the price of converting from my conventional spray equipment to HVLP in material savings. As I see it, HVLP has been oversold. For a large industry it makes a lot of sense because of the saving in material and the reduction in overspray, but for one guy, like me, working in my own shop, the only advantage would be less overspray, and since I don't have a problem with overspray, well... that doesn't leave much advantage.
So anyway, if you are setting up a new system and need to buy all new equipment anyway, consider HVLP. If you, like me, already have conventional equipment, use it.

[Graham McDonald]

Depends on whether you want to have a coloured/stained finish or just a clear lacquer. In either case lots of sanding to get all the scratches out. On maple to at least 180grit and spruce 280 grit. The important thing is to have the surface you are going to put lacquer on as flat and even as possible. Look for gaps around the binding and/or rosette and fill them before you start to spray as the lacquer is just going to sink into them. Under just a clear lacquer on light coloured timbers like spruce and maple the most un-noticable filler is a mix of lacquer and fine sanding dust (of the wood you are filling). It needs to be left for a week as it shrinks back, and two applications is usually necessary. Then more sanding. There is always more sanding.

For a solid coloured tint or a sunburst there are others better qualified to give suggestions, and there are various approaches of methodology.

Once I have a flat uniform surface to put the lacquer on my routine is three double coats half and hour apart the first day, repeat that the next day without sanding and then leave for a week. Sand back quite aggressively (like 180grit) to get an even flat surface. and then put on another three double coats and leave for a couple of weeks. If your preparation was good enough it should be ready for final cutting back and polishing.

If, after the 180 sanding, there are still shiny patches these can be filled with thickened lacquer (a small amount left in an opened jar until the thinners evaporate to the consistency of honey) and another three double coats applied, left for a week and sanded back and then the final coats applied.

The 180 grit sanding might be a little risky if you have colour coats under the clear, as you do NOT want to sand into the colour.

Alternatively wipe on a couple of coats of shellac and then some drying/buffing oil such as tung oil or what is sold here as Danish Oil.

cheers

Just glued the neck on my first mandolin build, so I'm getting dangerously close to applying a finish. I've decided to just spray a lacquer finish instead of going through the whole varnish/french polish rigmarole.

I did a search of the forum and could only find disparate snippets of info on the subject, but basically, what steps do I need to take to get from in-the-white to a nice finished mandolin using lacquer?
I have access to spray equipment (although not a whole lot of experience/skill), so I won't have to resort to aerosols.
Any advice would be much appreciated.

[Jim Hilburn]

If you do 6 coats you may want to do 4 then 2 instead of 3&3. Then you have more to work with on the initial sanding. I use micro mesh with mineral spirits but if you do soapy water stay away from the tuner holes or the water will get under the lacquer and split it. I assume there's ways to avoid that but staying away from water is the best.
I use a very nice hvlp gun and highly recommend it even though there are some things to know about it. I seal like John with a touch up gun at high pressure because I use a premix dye that will dissolve if too much lacquer hits it at once so mastering light early coats is important or you can use water stain but that's another whole subject. I've found that I can turn up the pressure on the hvlp and it will mist the fluid much like a conventional gun for the early coats and then dial it back to 25 lb for the final coats
I have a friend who's making cigar boxes and he's doing pretty well with Deft rattle cans.

[Graham McDonald]

There you go, four people who spray lacquer, four opinions

I just noticed a typo in my previous post. I spray three coats half an hour apart but I live in a really dry climate and lacquer flashes off very quickly. Somewhere more humid in the summer will have the lacquer acting differently I suspect.

One of my colleagues on the ANZLF has posted a couple of videos an lots of other relevent info on lacquer spraying here He is a specialist car repair sprayer in his day job and a very tasty builder of ukuleles the rest of the time. Good practical information and he lives in a seriously humid part of the world. There are few tutorials and how-tos by him on the site.

Just remember at worst you can sand or scrape lacquer off and start again!

cheers

[justinj]

I forgot to mention, I will be doing a hand-rubbed sunburst with alcohol-based dyes. About the dyes, I bought them a while ago and two of the colors started leaking out of the bottle. I threw those out, but are the others still good? Do these things have a shelf life?

I plan on using Behlen Stringed Instrument Lacquer as I can get it at Woodcraft and it does recommend using a vinyl sealer. Is there any advantage to using shellac instead for the sealer coat? What cut of shellac do you use? The directions on the lacquer also recommend sanding after the sealer coat, but I wouldn't trust myself to not sand through and mess up the stain.

What does a good HVLP system cost? I will be using my father's rig as he is an experienced sprayer of paint, but I don't know exactly what equipment he has.

Graham, I watched the video in the link and he reduces his lacquer. Do you know if that is for the type he is using or just in general? I'm assuming lacquer thinner would be used for that.

[sunburst]

-The dyes are probably still good.
-I think shellac looks better; clearer without the slight "cloudiness" I see with a vinyl sealer. I use approximately a 2 lb. cut, but I'm not exact about it.
-Sanding the sealer must be a very light sanding. Just a quick brush over with sandpaper to refresh the surface.
-HVLP systems range widely in price. I haven't kept up with brands and pricing, so others will have to fill in that blank.

[Jim Hilburn]

To me the issue of sealer is more about protecting your color from being compromised than lacquer adhesion. I've only recently begun sealing with shellac and have done quite a few instruments with lacquer only. I learned long ago the hard way that a very wet coat can disturb your color, basically re-liquify it. But another aspect of that is that I spray my sunbursts which means the dye is sitting on top of the wood more than soaked in like when you hand rub it.
my only experience with vinyl is that it goes on like lacquer and could be just as much a problem as straight lacquer as it goes on. A hardware store option is Seal Coat shellac so you don't have to mess with mixing your own.
The advice I got from Mike Kemnitzer in 1981 when I was going to start doing lacquer was to get a good touch-up gun that could be used for both sunbursting and applying lacquer. I still use the gun I bought then for coloring and also for the shellac sealer coats but it's asking a lot of it to move enough material for top coats so that's what I have the Sata for. But if you are hand-rubbing the color then just a bigger gun would be what you need. My Sata was pricey but there's a lot of imported guns that are very inexpensive like so much of the imported stuff we get. Oh, yeah, the Sata is also an import but from across the Atlantic.

[sunburst]

I, too, got away with spraying lacquer for many years without a sealer, and I started sealing to help "lock" the color in place, but as I read and listened more, it started to get through to me that lacquer doesn't have very good adhesion to wood, so the sealer is recommended by lacquer manufacturers so that their product doesn't peel, flake, blister, or otherwise have adhesion problems. I figure; if the maker's say it improves adhesion and it doesn't hurt anything when I use it, I'll use a sealer even when there is no color.

[Darryl Wolfe]

Not to derail, but do you have the minijet Jim?. I just got a minijet 4 Sata and have not used it yet

[Austin Clark]

The 180 grit sanding might be a little risky

As it is your first time, I would strongly suggest you stick to 320 or 400 grit because it will be difficult for you to judge how much finish you are or are not applying. It is waaaaay too easy to sand through to your color. On that note, make sure you keep some of your mixed dye around after sunbursting to fix your sand-throughs.

Also, for de-nibbling your seal/dust coats, I would use 600 and a very light touch. You are not really sanding here, just knocking down the raised grain and dry grains of finish.

[j. condino]

Great finish work is by far the hardest part of making instruments; there are no fast and easy shortcuts. The best thing you can do is find a mentor nearby who can show you the ropes. If you are going to mix handrubbed dyes with a solvent based finish, I'd use water base for the dyes or you may run into more problems....

I had about $1500 in traditional guns, sold them all because everyone told me I had to get an hvlp setup, spent a lot of money and bought the SATA and a couple of other guns, and gave every one of them away in frustration. A nice Devilbis 503 touch up gun and an Iwata airbrush will give you some of the most beautiful, fine quality 'bursts on the planet and will last a lifetime. For me, finishing instruments is about finesse and delicate precise work, and has nothing to do with high volume. Don't buy into the hype!

Ask ten more luthiers and you'll likely get 15 more responses....

j.
www.condino.com

[justinj]

Should sanding between coats be done wet or dry?

[Marty Jacobson]

If your dad sprays paint (latex house paint), then he may have an airless paint sprayer. Do not attempt to spray lacquer with an airless rig. It will just cause havoc to the rig and do a Jackson Pollock number on your instrument.
He may also have an HVLP rig for spraying trim. If that's the case, then make sure you install a #1 air cap and 1 to 1.5mm tip with matching needle.
If your dad sprays cars, then whatever he has will probably work with lacquer without any major changes being needed.

I have a Turbinaire HVLP I got for $150 on Craig's List, it's 20 years old but takes a lickin' and keeps on tickin'.
HVLP units range from $2500 (Binks/Capspray) to around $500 (Earlex).

Whatever you have access to will work, as long as it's not an airless sprayer. Learn to use what you have access to, and all will be well.

[justinj]

He mostly sprays metal (ornamental ironwork), but also wood furniture and boats. He says he has the capabilities to do lacquer, but I don't know specifically what system he's using. I'll have to ask him next time I see him.

[Jim Hilburn]

Darryl, I got a 2000 Sata digital and you can paint a Camaro with it. I'm sure the mini jet would probably been a better choice but this was what Grizzly had at the time. But it is very versatile and can work as well on a mandolin. Over in the thread about my 62 construction is a video I made of me doing a lacquer coat but be sure to turn the sound off so you don't have to hear thee compressor.
Before that I used a Sharpe 975 conventional. Learning what the difference is is what got me in trouble. When you spray at 25 lb the sata is basically shooting out much larger globs of material than a conventional which mists it more. That's what causes the overspray and waste of material. So the Sata can lay down a nice coat as all the bigger particles coalesce on the surface but those individual particles can also re-liquefy your color more easily.
Water stain is a great way to avoid this problem but it doesn't spray well and raises grain. Hand rubbing a nice sunburst with it is the pinnacle of a beautiful finish IF you have mastered it or it can be a blotchy mess. look at Gilchrist or Mowrys work to see how great it can look. But it's not something I've mastered. The alcohol colors I use seem more vibrant than the water dyes I tried although there were a lot of options to try that I never got to.

[Rick Lindstrom]

A word about the Behlen Stringed Instrument Lacquer:

I've been spraying a guitar over the past couple of weeks with the Behlens, using conventional spray gear. I checked the suggested spray schedule on the can, and if I interpreted it correctly, they suggest doing the initial coats at full strength, and the final coat thinned by half. I was suspicious of this because I'm used to thinning lacquer for spray, but decided to give it a try since it's been, conservatively, 25 years since the last time I sprayed lacquer, and things may have changed Anyway, I gave it a try, and definitely did not like the results- orange peeled, pebbly coats. I thinned by about 25-30% and tried again. Thinned, the coats flowed out and leveled nicely just like I remember from way back. You might say it's my decrepit technique, but I found that spraying is a little like riding a bike- you don't forget. After the initial passes with the gun, it all came back to me.

Anyway, my suggestion is to be leery of the instruction not to thin. And by all means, practice on scrap first.

[Jim Hilburn]

Trying adding photo with ipad.
Anyway this is about what's good about lacquer. I'm putting #15 back together after being taken apart several years ago to reset the neck. This is 14 year old lacquer after polishing with Novus. Its probably quallac or sherwins. This is from an era when I was using an old craftsman gun from a pawn shop and sprayed in the garage. There's a lot of ultra blush, like little bubbles but mostly still looks pretty good.

[sunburst]

Just for reference, my first real spray gun was a Sharpe model 90. I bought it to paint my Sunbeam Alpine (that's a car, for those who don't know, I had a Craftsman gun when I painted my '49 Ford before that) and used it for spraying instruments (and everything else) for years after that. Eventually, it became "obsolete" and I could no longer get parts for it, and finally cleaning and reassembling it no longer got it working well.
I had a severe finish problem on the back of a certain guitar a few years ago, and ended up using fish eye eliminator to solve it. All the conventional wisdom says 'use a separate gun for fish eye eliminator, don't let it contaminate anything else, keep it under lock and key in a separate building' and so forth, but the tech on the phone (at McFadden (remember them?)) said all you really have to do is rinse the gun with lacquer thinner and it's fine after that. Anyway, I went to Harbor Freight and bought a $30 gun for the fish eye eliminator and the gun sprayed great! Better than my old, worn out, obsolete Sharpe, so it became my main gun. (The tech was right, I rinsed the gun and it worked fine afterwards for everything I sprayed through it.) One day, I knocked the Harbor Freight gun off of a work bench and it landed on the concrete right on the tip. That ended it's life right there. I could have replace the tip and nozzle if I could have found the parts, but it was a $30 gun! I tried to get another like it from Harbor Freight, but they didn't have that one anymore so I got a different $30 gun. It's still working fine and spraying fine finishes.
When I worked at a cabinet shop many years ago, I sprayed cabinets with and Apollo HVLP system. When I sprayed banjos (and other instruments) for a manufacturer, I used a Binks 602 (I think...) set up for pressure feed with a remote "paint pot". That was the best! No paint cup on the gun so I could move it as fast as I wanted without sloshing the material and introducing air bubbles, I didn't have to lift the weight of the finish material to spray, turn it at any angle, so surging, no bubbles... That one became obsolete too and I got a Binks 2001 to replace it (never liked it as well). (They've since gone to HVLP there, and had lots of problems with it.)
Then I left that place of employment and went back to a conventional gun with a paint cup. I'm in the process now of setting up a new spray room and I will once again install a pressure feed system with a conventional gun.
The point is, as long as we have at least decent equipment and learn to use it, we can get a good finish. I'm sure I would appreciate the performance of a high dollar system, but it just doesn't seem to be necessary.

[sunburst]

Anyway, my suggestion is to be leery of the instruction not to thin. And by all means, practice on scrap first.

I second that. Lacquers today are formulated with lower solid content; "ready to spray" or whatever. But unless you can spray them heated or can really spray high volume with good control, adding a little reducer sure smooths things out. I reduce to a viscosity that I like, though I don't measure it with a viscosity meter, just watch as it runs and drips off of the stir stick, and that requires adding a little reducer. (I'm currently spraying Mohawk lacquer.)

[dunwell]

Lots of good advise from many others. I'll just add three things that over time I've found to be very important for me:

- There are a lot of good lacquers but when I went to using the McFadden lacquer it was day/night good for me, I'm using an Acuspray HVLP conversion gun. I could push on nice wet smooth coats and it would level and cure out w/o runs or orange-peel, etc. shooting about 6" away from the surface. McFadden went toes-up but their formula has been picked up by Seagrave. I just picked up a gallon from StewMac for a guitar I'm finishing right now and it is the real stuff. Expensive now though but to me worth it.
http://www.stewmac.com/shop/Finishin..._Lacquers.html

- It is hard to judge the thickness of finish by saying X-Number-of-coats since coats are relative. Before you begin spraying but after you have your prep and seal coats on, use a vernier caliper of micrometer through the sound hole (A-model) or F-hole (Fstyle) and mic the thickness of the raw wood. Pick a spot that you will easily remember the location of. The shoot on about 4 cross-coats and let dry over night. Mic. Smooth sand, mic again. Record all this on your build sheet. You are going for ~ 8-10 thousandths of final with it rough smoothed but not cured out yet. I sometimes will shoot one more cross coat to sides and back after I have the top thickness, it doesn't hurt to have that just s scooch thicker just for protection. Let hang for at least 4 weeks, depending on your climate, and then do your smoothing wet sanding back down to ~6-thou on the top.

- Micromesh for wet sanding. Again, lots of good papers out there, but I've gone completely to MM for my finish sanding. After I start shooting lacquer I don't touch it with anything coarser than 1800mm and that only for scuff sanding between coats and the initial level sand. Then 2400mm and 3200mm for my final level and smooth and then to the buffer.

FWIW,
Alan D.

[justinj]

In the video Graham posted, he is reducing to 50-50. Is this too much reduction for Behlen? Also, do the reducers and retarders have a shelf live? Will they expire before I use them up?

Also, what's the deal with micromesh? I'm not familiar with that product.

[Dr H]

Also, what's the deal with micromesh? I'm not familiar with that product.

http://www.rockler.com/product.cfm?p...FQZyQgodwVAAjQ

While I am not a pro like some of these guys, I have done a fair amount of finishing, so let me just add a little caution about micromesh from my own experience. You want to be careful not to oversand too soon.
When I got my first set of micromesh pads, I went nuts with them. Diligently applied, you can in many cases sand bare wood to an almost glossy surface with these things.

And that's what I did to couple of projects I was working on (not instruments). What I discovered is, if you get the wood too smooth before you apply finish, a lot of finishes won't adhere well. I ended up with a laquer "finish" that pealed off like cellophane tape. Had to strip off all the finish, rough-up the wood a bit with some 320-grit, and do over. That finish stuck.

Once you have the finish built up, though, these things are great on the final coat.