Behlen's Instrument Lacquer

[mandomanmike]

Looking for some experience here. I'm wondering how many coats I can do before I need to scuff sand the Encore Brown lacquer I'm using. Is it helpful to sand lightly and then resume with additional coats? And then, do I need to scuff sand between the brown and the clear coat? Anyone?

thanks

[sunburst]

I normally apply two or three coats, sand, then apply two or three more, repeat until done. You should sand after each session of applying lacquer, when it is dry enough, then apply again. (Daily applications are normal, but you can wait longer in between.)

[Jim Hilburn]

I try to apply about 7 total coats. The first coat is very light to seal my color. So I do 4 coats before sanding.
No matter how well you've final sanded there will be a texture from the wood, especially the spruce that follows through every new coat. You need enough build to be able to level all that texture without any risk of cutting through to the wood.
When your wet sanding (some do it dry at this point) you will create a dull surface with shiny spots which are the lowest area. You want to get down to those spots but with extreme care. It may be best just to leave some of the deepest for the next coats to fill.
When you spray the final coats you'll see they go on flat and smooth since they're laying on the leveled surface you created with the first sanding.
So the idea is to build enough to safely do an intermediate sanding and end up with enough to fine sand and buff but still be as thin as practical.

[mandomanmike]

Great explanations Jim and John--exactly the information and detail I was looking for. I should have asked what grit of sandpaper for the sanding between coats. Assume pretty fine, and I know when I get to the final sand I will be looking at around 2000 grit

I really appreciate the info!

Mike

[mandomanmike]

oh and one more---I know this varies and I know I will just need to pay attention to the flat and smooth as Jim described. But just curious about the total number of coats it usually takes.

thanks again!

Mike

[Michael Lewis]

The number of coats depends on how well you have prepared the surfaces.

Once you have achieved the density of color you want go to the clear coats. 320 grit between coats should be good. Sanding with 800 grit before spraying the final coat is plenty fine, some don't use finer than 220 all the way through except for the final sanding and buffing. There you need 800 grit, or finer if you like.

[Lefty Luthier]

Over the years I have found that spruce tops usually required 12 to 14 coats of lacquer in total. I normally spray 2 coats about 1 hour apart and then let it cure for 2+ days before sanding. I start off with 320 grit water sanding and then at the 10th coat, go to 600 grit water sanding. Before the final coat, I buff well with a water/0000 pumice paste and then after the final coat, give it a good coat of polish and vigorous buffing.

[Jim Hilburn]

I try to keep lacquer very thin and I generally shy away from 320 and just put in the extra effort with 1500 micromesh.

[Jim Hilburn]

I just happen to be spraying some lacquer right now and thought I'd add a little to what's been said.
The question of how many coats is pretty subjective because what I call a coat and what you call a coat may not be the same thing. Depends on how the lacquer is thinned, what gun you have at what pressure, the fluid to air mix, and how fast or slow you make your passes.
So what's important is still getting an adequate build to be able to sand without cutting through to the wood. If you want to be able to go after it with 320 and get the job over with in a hurry, then a few extra coats may be in order.
This photo was taken right after the 4th coat went on. You can see that the spruce lines are still there because the softer wood between the annual lines sands away more than the hard annuals during the final sanding. So you have to build enough finish to level the lacquer without hitting the top of any of those annual lines.
So to achieve a thin lacquer finish you should be getting close but not going through. Then once you get a level surface by sanding the first set of coats you can add just enough topcoats to sand away the orangepeel and leave enough for buffing.
For the factory finishes of the 50's through the 70's they didn't fool around with trying to get that thin finish, they just piled it on so they could buff away any imperfections.
So with that I'm going to go do one more coat and I'll be ready to start sanding in 2 days.

[Michael Lewis]

You always do nice work, Jim.

[Jim Hilburn]

Here's an update about sanding lacquer.
In this shot I've sanded the recurve area flat but still have to work from the other side up to the f-hole. I used 1500 Micromesh lubed with mineral spirits with a little mineral oil in it.
In the same way that the original lacquer coats continue to show the wood texture, now that it's leveled the next coats will go on just as level with some orangepeel from the way it splatters on.

[Mario Proulx]

I generally shy away from 320 and just put in the extra effort with 1500 micromesh.

You probably already know this, Jim, but for those who aren't aware, 1500 micromesh is equivalent to regular 400 grit.

[Jim Hilburn]

To be honest I can't say I did know that, but I know it's the flexability that keeps it from being too aggressive. I do the major area's with the foam block and the tight area's with my fingers.

[Mario Proulx]

Oh, okay, well, here's a chart to help out with converting the other MM "grits".

[sunburst]

Interesting how different people work. I look at that and immediately think 220 grit, and I think stiffer paper helps keep me from being too aggressive. Folded 1/4 sheet of "freecut" 220 and light pressure, dry sanding. I feel like I'm more likely to sand "contours" into the surface with finer grits and with less stiff paper. The aggressiveness of 220 makes it cut faster so I spend less time sanding, and thus have less time to screw up! <g>

As usual, it's the results that count, not the methods, and from what I've seen, Jim's results leave nothing to be desired!

Thanks for the chart, Mario, I'm keeping that!
I think it's worth saying, however, that the scratch pattern of micromesh is finer than that of sandpaper of equivalent grit size because of the softer backing and because of their method of affixing the grit. In other words, one can sand a finer, smoother surface with 1500 grit micromesh than with 400 grit paper even though the grit size is similar.

[Tony Francis]

This is a really great thread thanks everyone.

Jim, once you have sprayed your build coats and then leveled like you show here, when you say you spray the next coats, are those coats the same mix as the build coats or do you do a really thinned flow or flash coat? And once you spray your last coat how do you proceed with buffing?

Also, You mention sanding with minderal spirits and mineral oil. Why do you prefer this over water sanding? I always found it clogged my paper more than water sanding but it seems lotsa folks (and way better finishers than me from whom I want to take advise!) use spirits for sanding.

Mario, Thanks for that chart its really a great help.

John, what kind of sanding blocks do you like to use or any at all?

Best,

Tony

[sunburst]

I seldom use sanding blocks, but when I do I use rubber ones; the 3M type that take a 1/4 sheet strip of sandpaper. I use them for the front and back of the peghead. I almost never use wooden sanding blocks because I have too much arthritis in my fingers, mostly from over use and mostly from sanding! I also seldom use orbital power sanders because the vibration from them is so hard on finger joints.

I cut a sheet of sandpaper in half, then cut each half in half so I have 4 rectangles, not strips. I fold those in half both ways, tear along one crease to the center and fold into a piece that is four layers thick. (The tear makes it so that no grit-coated surfaces are touching when the piece is folded.)
That folded piece is stiff enough for most work, but I can put a piece of cardboard (like a cereal box) in the fold to stiffen it more, or a pre-approved credit card or old hotel room door "key" if I need it stiffer still.

[Mario Proulx]

My favorite sanding blocks are large pencil erasers; good and stiff, yet just enough "give". I buy packs of regular size ones and cut some up into odd shapes for reaching into corners, etc... And if you can find one of the huge novelty ones, grab it! Mondo handy....

Glad y'all like the chart' I have one printed and stuck on the shop's wall; around here, "P" rated sandpaper is sold right alongside, and often seemingly randomly interchanged with, ANSI rated papers. I'm forever referring back to the chart to see what the heck I'm actually using... And now we have micron rated papers, too!

Something that I think bears repeating in this thread is Michael's post, and that is that how much finish we need to apply depends greatly upon how well we prepped the surface. We've just had a good thread over on the MIMF regarding raising the grain which covers this issue. I was surprised at how many didn't know to raise the grain, or why.

I think the scratch pattern of micromesh matches the equivalent grit size, but the difference is that the micromesh is much more uniform, and unlikely to have a random deep grit. The stuff also lasts and lasts! I got away from using it these past 7-8 years; may be time to go back and revisit that fine product...

[Jim Hilburn]

I use the same jar of lacquer all the way through and I'm pretty bad about how I go about thinning. I just do a dollop of thinner in McFaddens. I know it's sold as spray ready but I like it a little thinner.
Water sanding is fine until you get to your tuner holes and suddenly you see splits in the lacquer where water is working it's way under the lacquer. The best sanding mediums are kerosene or some automotive paint cleaners like Prep-sol but to keep the peace at home ( my shop is in the house) I've found mineral spirits to work very well without the smell. It does slurry up but I wipe it off often to inspect my progress anyway.

[Tony Francis]

Good info here thanks everyone.

So after the coats are leveled and you spray a couple more, then allowing for cure time, do you progress straight to your fine paper before buffing or still working up through the grits?

Is there anywhere you can buy micromesh as individual sheets like the regular 50 pack automotive places sell? StewMac or LMI only sell the kits but I know Dick tools in Germany sell it by the roll.

Thanks again,

[Mark Franzke]

International Violin sells it by the sheet. I bought the kit and then some extra 1800-2400 sheets, because they do the bulk of the work. I also use the little square pads. They do a great job.

[Jim Hilburn]

Thanks for the link to International and the individual MM sheets. I just drove into the heart of Denver the other day to get some at Rocklers. I called first and they assured me they had it so when I got there there were 2 sheets of 1500 left. It looks like they're letting there supply run out.
The great luthier D.W. Stevens told me he never touched his final coats with anything less than 1000 long before MM was available. I've been starting with 1800 and moving on to 2400. On F styles I do the scrolls through most of the grits since I don't want to hit the ridge with the buffer. Same with some of the tight spots and around the f-holes.

[Jim Hilburn]

according to Mario's chart 1800 MM is the same as 600 W/D but there's no way they sand the same. 600 seems much more coarse.

[Mario Proulx]

Equivalent, but not the same. The scratch pattern is definitely nicer with micromesh.

There's also a great deal of quality control variation between brands of papers, also, with the cheapest ones way too often having stray grits that are larger than specified, so you're scratch pattern with a no name Chinese 1000 may have random scratches as deep as you would have had using 220. Go with the better brands, 3M and Norton being my faves.

Tip I read someplace years ago is that of 3M's abrasives in 800 grit and higher are made in a separate plant from all the rest; their 800 grit, therefor, should never have even one stray grit that is larger than specified. Since learning that, I've began at 800 after the final coats; never lower. Seems to work....

[Martian]

Facinating info folks, but I wonder if I could have a few things cleared up in reguards to Behlen. When you folks are speaking of light coats is that literally light ,or thin? And in reguards to thin coats (wash coats, flashcoats),what thinners do you recomend ,for instance, lacqour thinner, paint thinner, and other thinners,and to what mixing percentages? as in 80/20, 60 40? I hate to seem ignorant on these issues, but I just left home depot, and realised how many "thinners" there on the market? One friend, who has helped me out repeatedly on this forum had even said that humidity on any given day will dictate to how much thinner he would use. Any input?

[Jim Hilburn]

Lacquer thinner. The Home Depot stuff will work fine.
You really just have to go through it to get the feel of how lacquer goes on. But I really recommend getting some of the finishing video's Stew-Mac sells. They explain it all very clearly and you get to watch them do it.

[sunburst]

I use the "Home Depo stuff" for a cleaner. For real lacquer thinner I have to go to specialty places, and I usually use the slowest thinner I can find. When the humidity is high, I add retarder.
Of coarse, Jim lives in Colorado and I live in Virginia. It just might be that he never sees humidity like I can have for weeks at a time in the summer, and he can probably get away with using faster thinners than I can.
"Generic" hardware store lacquer thinner is usually "wash grade". Automobile paint stores...some of them...still carry different grades (speeds), some paint stores, and some better hardware stores, but high quality lacquer and products are getting harder and harder to find, and mail-order is getting to be the best way to get stuff, even though the haz-mat shipping charges suck. Sometimes I think I'll just quit bothering with it and varnish everything... especially since folks will pay quite a bit more for varnish on mandolins!

[Mario Proulx]

When I was still shooting nitro lacquer, like Jim, I just used hardware store lacquer thinner, but like Jim also, my climate is a lot drier than John's and others', and blushing has never been an issue I had to deal with, so the fast, generic thinner was fine. Paint thinner is not lacquer thinner, so don't even think of trying to dilute lacquer with it!

How much to thin depends on everything about your setup and climate, so you can't go by anyone else's recipe. My rule of thumb for thinning, be it a mandolin, guitar, or a car/truck, is to only thin as much as necessary for my gun and I to shoot a smooth coat. You need to play around a bit to find what your gun wants, often tweaking the amount day to day, as well as for how -you- spray.

To me, a light coat is an almost dry coat, where it isn't quite "wet" looking yet. Hard to describe, but the opposite is easier to describe, and that is a heavy coat, which is wet and glossy, and nearing the point of wanting to run or puddle. I've always leaned more to the dry, light coats than the wet ones, even on my final coats, but some guys can do wet coats so perfectly they get away with fewer. I was never -that- good!

[Dale Ludewig]

I can't use hardware store lacquer thinner unless I add retarder to it. It's simpler to just go to the good paint store and buy the slow drying stuff. I spray fairly wet and around here in the summer I still add retarder. The humidity gauge in my shop is now sitting at about 80. I'm not spraying anything right now.

[Lefty Luthier]

Facinating info folks, but I wonder if I could have a few things cleared up in reguards to Behlen. When you folks are speaking of light coats is that literally light ,or thin? And in reguards to thin coats (wash coats, flashcoats),what thinners do you recomend ,for instance, lacqour thinner, paint thinner, and other thinners,and to what mixing percentages? as in 80/20, 60 40? I hate to seem ignorant on these issues, but I just left home depot, and realised how many "thinners" there on the market? One friend, who has helped me out repeatedly on this forum had even said that humidity on any given day will dictate to how much thinner he would use. Any input?

When I say light coat, I mean that it is just sufficient to flow smoothly. Too light a coat and you get goose bumps, too much and you risk a run just when you have the finish even and smooth. Best method of estimating the percentage of thinner to use is to spray a test piece and check for blush or runs.

[Tony Francis]

When you folks are speaking of light coats is that literally light ,or thin? And in reguards to thin coats (wash coats, flashcoats),what thinners do you recomend ,for instance, lacqour thinner, paint thinner, and other thinners,and to what mixing percentages? as in 80/20, 60 40? I hate to seem ignorant on these issues, but I just left home depot, and realised how many "thinners" there on the market? One friend, who has helped me out repeatedly on this forum had even said that humidity on any given day will dictate to how much thinner he would use. Any input

I like to spray a nice wet coat, but not too heavy or you will get runs. I found spraying dryer coats I was quessing at coverage, but with a 'just wet' coat you can see what your doing. I thin my nitro 50/50 using fast thinners (slow in the summer and sometimes with a splash of retarder), but what Im using down here is not the same as the instrument lacquer like whats available as in the USA. Our Nitrocellulose is old school and designed to be sprayed hot, although spraying cold with thinners is much more common outside factorys. So my 50/50 could be the same as your ready to spray, its hard to tell without one of those viscosity meters. Im still trying to master the process, but its a really high quality finish if you take your time and do it right.

Currently I spray 6 build coats, over three days, wait a week and level sand with 400 frecut. Then spray a flash coat (thinned 75%) and wait three weeks before wetsanding with 800 grit and then buffing with coarse and fine menzerna. This is really thin finish and I always sand through, and touchups are nessesary. A good nitro finish without any primers or sealers is a pretty challenging thing, But im always working on getting better. I really appreciate the help from everyone here.


Thanks again everyone for all the good info and links.

Best,

Tony

[Michael Lewis]

Tony, to help avoid sanding through your color, when spraying your clear coats just make a few extra passes where you are likely to sand through.

[Tony Francis]

Thanks Michael thats a really good tip.

[mandomanmike]

great thread!!!!

and I've got a couple of instruments finished and like the result of all the great advice

one more question

Once you get the final coat polished (1500 grit wet sand, then polishing compound followed by Meguiar's PlastX and Scratch X using microfiber cloth) I get an almost perfectly scratch free finish....almost. Is there a polish that eliminates all microfine scratches? Polishing wheel and compound? Or am I being way too picky. I want to know how to get a mirror perfect finish (not that it will last).

thanks so much to all who made this a rich source of knowledge and experience--I'm thankful for what I learned.

Mike

[Martian]

Just a quick ques. In a couple of posts I have read the terms "runs and blush". Runs I get. What is the cause, cure for blush? Also, I have practiced my test sprays on cardboard, should I be doing this on wood to see if it will blush?

[Mario Proulx]

Blush is moisture trapped within the coating, and appears as a white-ish haze. If not severe, it will often disappear when fully cured, but more often than not, a quick, thin spray with straight thinner or butyl cellusolve will open the surface enough to drive out the moisture.

[sunburst]

That's the explanation we've all been told, but I had it explained to me by a guy who makes coatings, (he is actually a masters degree educated guy who works as a technician at a coatings "factory") and he explained it like this;

When the lacquer is sprayed on the surface the solvents start to evaporate and the surface is cooled by evaporative cooling. If there is enough humidity in the air, the surface will "fog up" from the moisture condensing on the cool surface. The moisture isn't trapped in the surface, but if the fogging happens while the lacquer is still wet and soft enough it clouds the surface. Retarders added to the lacquer evaporate slower so the surface doesn't cool as much and the moisture doesn't condense.

[Mario Proulx]

Most interesting! Thanks for clarifying; as always, there's more to learn!