Opinions on best water based "lacquer like" finish

Thinking about spraying a water based finish over epoxy pore filler. Looking at water based due to the possible health hazards of the nitro. Anyone have opinions about the KTM9 finish sold by LMI, or the Target EM7000HBL sold by Stew Mac, or the EM6000. I also think that Sherwin Williams has a waterbased "lacquer." Any comments from someone who has experience with these products would be greatly appreciated please let me know what you think.

Have not tried any of these on an ukulele. I have had experience with the Sherwin-Williams Kem Aqua on furniture. It's fine for middle end cabinet work, but the rubbing qualities don't make it a candidate for an instrument finish, in my opinion.

Thanks for the response. So you have been using regular nito lacquer for finishing your ukes?

Pono said:

Thanks for the response. So you have been using regular nito lacquer for finishing your ukes?

Click to expand...

Sort of. I may be a bit prejudiced, but having worked for Mohawk for 8 years and having helped develop the finish, I like the Mohawk Musical Instrument Lacquer.

It's not quite a standard nitrocellulose, but as far as it's potential hazards, it would be classified as such.

I have been interested in WB finish myself. They also often have the problem of giving a slight purpluish hue. I prefer the slight amber cast of the old formulae nitro. I'll be checking back to see if anyone can recommend a good WB.

I like nitro much better than waterbornes. Nitro is easier in general, than waterbornes, in almost all aspects. Color wise, it is better. That said, I am not current on waterborne finishes, there may be some decent ones now. My favorite in the past has been Enduro, I believe it is made by General Finishes. It polishes acceptably. I will be using nitro over an epoxy filler, though Will likely also be experimenting with the polyester finishes as I have a project that specs it right now. Go nitro.

I ordered some of the KTM9, EM7000, and Cardinal Lacquer and I am going to try all three on plywood and see how much better I like the nitro and decide from there. Unfortunately I am betting that I will not like the waterborne as much as the nitro and I will end up having to change the setup where I spray. Trying these out should also give me some experience using my turbine system. I will let you all know how it turns out.

When testing out finishes, my suggestion is to use the same wood, with the same characteristics, as you'll be working with. And go through every step from sealer coats and pore filling (if that's what you want) to final buffing. Some finishes will lay down differently while others will sand and buff differently. With my limited experience (three years ago) with EM6000 I found it worked very differently from nitro. Because the water based lacquer doesn't melt into the previous coat timing between coats was critical and I experience some witness lines when sanding. (I seem to recall reading that sanding dry, which has it's own set of problems, eliminated this problem.) The finished result always had a sort of fake look to me along with that slight bluish cast it's known for. (Some people add an amber dye to the lacquer.)
I don't mean to sound discouraging. I really wish more people would try the water based products and get down a schedule that works. The more it's tested, the more we'll all learn. Nitro and all the related solvents is nasty, nasty stuff. I know first hand how bad this stuff is. It can cause severe health problems including auto-immune diseases. My suggestion is that you need to go to extremes in protecting yourself against the vapors, the gassing-off and skin contact. I'm protecting myself pretty well lately, but still, with every uke I spray I feel like I'm trading a little bit of my life away.
Good luck with your experiments and keep us in the loop.

You'll likely find that there's a difference among lacquers, too. I used several gallons of cheapo Parks, which I got through Ace Hardware. I liked it. I like Musical Instrument lacquer from Stew-Mac better, but it costs a lot more. We just tried Cardinal lacquer at Huss & Dalton. The Cardinal people were very helpful but our finish man didn't care for it.

I'm in the same boat as you. I have several instruments to finish and intend to try a few new finishes. So many top flight guitar makers have used KTM9 that its hard to believe it might be inferior. We'll see. Its my intention to get away from nitro, so I'll work hard to make the others successful.

Chuck, that's a very cool picture. I once made a "spray booth" out of plastic sheeting and the static made me crazy. I never thought to try fabric. Old bed sheets maybe? The white light coming in looks very pleasant.

jcalkin said:

Chuck, that's a very cool picture. I once made a "spray booth" out of plastic sheeting and the static made me crazy. I never thought to try fabric. Old bed sheets maybe? The white light coming in looks very pleasant.

Click to expand...

John, my spray booth is a small existing green house (covered with clear panels) attached to my shop. But the interior is actually made from the walls and top of an old "Light Dome" craft tent, left over from my hippie potter days. Very thick vinyl panels with heavy duty zippers and snaps on all sides. Unzipping one panel exposes the bank of exhaust fans on the far wall. The walls let a lot of light in and are easy to clean. I can even unzip the walls and hose them off in the back yard.

Chuck thanks for the reply. Safety and ventilation will be my priority. My plan was to take some cherry or maple plywood panels and pore fill with epoxy then finish all the way to buffing and then compare. Do you think that the cherry or maple plywood will be a good enough match the way this will work for Koa?

The pores on those woods are totally different. Whenever I test something I like to do it on the exact material that I'll be using. Unless you have a stack of scrap koa lying around I can understand your reluctance to do so. You'll be OK. Just make sure you go through the entire process. Some people assume that just because a finish goes on well that you won't run into any other problems along the line.
Also, make sure to count your coats and measure your thicknesses, both wet and cured. I use yogurt cup lids to block my sound holes (backed with a big, fat sponge behind it). During and after spraying it's easy to tell exactly how much lacquer I've applied because it just peels away from the plastic lid.
Also make sure to test for adhesion. For me that's the most important test of any finish.

If you are doing the experiment as your first time, for practice also, try something with edges. Flat surfaces are far easier. The corners are where you are likely to burn through. Maple and Cherry are completely different. Cherry is open enough to definitely need a filler. Maple is more closed, a filler is not as necessary, though with just a little time pssage, the structure of the wood will telegraph through the lacquer much more than if an epoxy filler/ sealer is used. . Mahogany would be a good practice wood, if Koa is not an option. Koa will be very different than Cherry.

Sounds like you are working toward a full polished lacquer finish? If so, my 2 cents say, spray carefully, make sure the corners are coated sufficiently. The epoxy fill coat needs to be perfect, what you leave there is what you will end with, essentially. Sand it carefully, and fully 'flat'. When doing the final 'flat' sanding of the finishing prior to buffing, treat every sanding stroke as a 'cut', in other words, be careful and patient. Time spent earlier in the finishing process, getting things right, is more efficient than trying to fix issues it the final stages. Take the time to be sure your edges are 'broken' exactly as you like at finish, prior to the epoxy filler, and zero flaws in the wood.

If the lacquer is not laying flat easily, either adjust the fluid needle more open, add thinner (acetone) or both. If lacquer is building too quickly, reduce the fluid. Watch buildup on the air nozzle, this can also impair layout, though on a single uke, buildup should not be an issue. The orifices on the air nozzle are precision, caution with metal in this area... Strain your lacquer always unless you are ok with the possibility of fluid born contaminants. Be aware of ALL temperatures, and relative humidity.

All good tips Chris.
And don't forget to use retarder if needed (I always use 3% to 5% for my conditions.)
Sanding is not a time to let you mind wander. Whether by hand or with a power sander, it requires focus.
You are also correct about the surface being perfect being shooting your first coat. Don't use lacquer as a filler or to hide your imperfections!
And yes, all corners get hit twice.

Just as I'm glad to not have to repeat my teenage years, I'm so glad I don't have to learn finishing again. It's probably the reason I stay with nitro.

Also, on your coats, you want full 'wet' coats, not just kinda wigglin the gun around building up lacquer droplets like sand drip castles, feeling satisfied cuz it is not running... You want the lacquer to 'hang, right before the point where it sags, or runs. You want it wet... wet is good! You knew that already.... nevermind.... When you finish spraying, you should be able to inspect, and feel this warm fuzzy feeling looking at the perfect sea of glass you have just layed down., with zero imperfections...... If not, don't worry too much, someone else has likely also not sprayed a perfectly glassy coat, you are not the first..... Spray methodically.... you will develop a feel for the length of time between coats, depending on a lot of factors, possibly including your mood. If things get out of control, let it dry.

Just remember that the main ingredient of water borne lacquers has so far been wishful thinking...

I had a very expensive custom made and sprayed with a water based finish...in a few days to a week, it started
deteriorate and peel.. I am sure the builder did a great job and did not contaminate the surface before spraying.
he had to re sand and learned his lesson and changed back a NC finish....you know at first he had the first thought
and concerns as you, but after he had to redo my uke, he quickly changed his mind..

Thank you for the advise. Wet coats just before it sags, I will try to find some mahogany with corners to practice on (had not through about that but makes sense), I will use some retarder, sand thoroughly when pore filling, perfect surface when I begin finishing, focus when sanding, and think wishfully that the water borne finish will work better than the nitro so that I don't have to deal with all the solvents and nitro. I am looking for a full polished lacquer finish. I have about 5 bodies and necks ready to pore fill and finish so I am chomping at the bit to get practicing so that I can develop some skill and decide what finish to use. Built a knockdown spray booth yesterday like the one in Jeff Jewitt's book and I have a Fuji Q3 on the way along with some finishes to try. Hopefully I can get some instruments finished by the end of the summer.

wet coats til it flows

If I were to go back to spray-booth-less finishing, I'd go with brushed Epifanes varnish over epoxy or for open pore, TruOil or Waterlox over epoxy, or do a great epoxy and maybe shellac job sealing and leveling job and send it out for topcoats and buffing. There's nothing like a full pro setup for doing good looking gloss finishes. I'd rather see a good satin or TruOil job than a bad gloss finish...of which you can see many at Healdsburg-like events...