Laquer Finish Problems

[Pappy]

I sprayed the finish on the bar I have been working on today. The shellac base coat on the cabinet and the Waterlox gloss for the bar top went on with no problems. When I applied the laquer I had problems with bad blushing in the corners. Humidity was around 50% so that may have been the cause. Varying the pressure between 40 and 60 psi didn't help.

Is there any way to rub out the blush without destroying the finish coat? After the first coat I wiped the cabinet down with a rag dampened with the reducer. That worked, but left streaks in the finish. If I have to do that again I will pick up the recommended retarder to add to the next coat.

The laquer is I'm using Gemini L93-4 Furniture finish.

[cabinetman]

Don - first I'll try to help you figure out what is making you blush

The major problem with spraying may be in your set up. Many different parts of the system can be a cause. Understanding the process may help you to get better finishes. An air compressor is basically an air pump. When running it is pushing hot air into a container (tank), which fills under pressure. The air going into the tank is hot air. This creates condensation in the tank and water, and other matter gained in the air in the process will store in the tank. This is why you should drain the tank regularly. I do it under tank pressure in order to blow out all moisture and whatever sludge builds in the bottom.

Next in line to check is the filter. It is fairly useless to have the filter mounted right at the tank where the regulator is. You should pipe the filter as far from the tank as possible. The reason for this is that at the location of the regulator, there is hot air under a lot of pressure, that blows by the filter some moisture and debris. If you don't have a long run to where you want to spray, pipe up as high as you can with a drain below to catch the moisture. If you have no room to take off at a 90 degree from that high point, just create a large "U" turn and come back down. What you want to create is to travel the air so it will cool, and get as much moisture out as possible. Remember, just moving the air will warm it.

Ideally, any line you set up from the compressor is more effective if it rises in height until your spray gun, with drains along the way.

Next is your spray gun. I've always used one of those bulb filters that screw on the the handle of the gun as a final filter. Try it, you'll see a difference.

Next is a little discussion on finishes. I'm a proponent of using like materials from start to finish. If I'm using lacquer, all the steps in finishing will be acetone based (lacquer thinner), such as a sanding sealer, and then finishing lacquer. If a stain, or dye has dried that has been applied to bare wood, your steps in the lacquer finish should be fine.

Where you have a problem is when ingredients from different bases have the chance to dance around together. Most of the compatibility problems I've had were due to preparation, rushing, or not being ready with the next step.

Now for blushing. The start of blushing can begin at the point of the tank, If enough moisture is carried out to your line and gets blown past the filter (it doesn't take much), it will merge with the air that enters your gun and...voila...blushing. Or, any moisture that collects in the line to the gun, that should be caught by that neat little filter I already told you about, but wouldn't be if you don't have it.

The mixture of how much air (to the gun), and the air/fluid mix (at the gun), can contribute to blushing, if the air mix is much greater than the fluid composition. Ideally, a lacquer finish would be almost problem free if you could get it to the workpiece without any air. If your air pressure mix is too high, the spray will cause a "drying" before it gets to the workpiece. So, depending on the type of gun you use, it's playing with the fluid/air mix. You do want the mix to atomize sufficiently, so that runs will be less likely.

Next, If the humidity is fairly high, as you spray, the spray pattern shoots through the air to your workpiece collecting moisture that's in the air. I've seen it so bad that mid air I saw the blushing occur when the lacquer carries the moisture to the workpiece. It's like it grabs a little cloud and transfers it .

So, the answer I found to help in the spraying end of all this is to add retarder to each cup. Even if the humidity seem low, it makes the lacquer flow much better. As a mixing note, in general terms, acrylic lacquer thinner can be used in both acrylic lacquer and nitrocellulose (NC) lacquer. Don't use NC lacquer thinner in acrylic lacquer. The term "acrylic" lacquer has nothing to do with water or latex. Furthermore, there are different drying speeds in lacquer thinner. If you're buying from a supply house that carries industrial products, you can buy a "slow" lacquer thinner, that will flow better than a faster dry.

Now for the fixes to your problem. You can mix up some lacquer thinner and 20% retarder, with a small addition of lacquer, like maybe 5%, and spray over the blush. It's much better to catch the blush while it's still wet, or hasn't cured. Pure thinner and retarder at that point may resolve it. If it is really bad, you may have to wet sand and respray.

I have since been using water based polyurethane, which has fewer problems, less of a health risk, and finishes off very nice. I get a very good finish with it. If you haven't tried it yet, it could be like a whole new adventure.

[downtheroad]

Working in the furniture touchup/repair field, our shop uses König touchup supplies designed for the professional. They are great products imported from Germany. They have a moisture/bloom eliminator in an aerosol that works great. It has saved us from lots of extra work many times.
http://www.konigtouchup.com/BuyNow/m...eandbloom.html

[JimD]

I love Resisthane. A water based pre-catalyzed lacquer. Available from Hood finishing for about $35/gallon delivered. I do not know nearly as much as Cabinetman just said but I have not been unable to mess up Resisthane. It can be used as a sealer so you do not need anything else. You can also brush it if you want for touch up on on small parts. It dries so fast you may have difficulty brushing large stuff. I am using white Resisthane currently on plantation shutters. I previously used clear gloss. Both work for me. I know the clear is rated for kitchen cabinets, I don't know about the tinted but that is probably not what you are doing.

Jim

[Pappy]

Sorry for the delay in responding. Thanks for the info and suggestions. C-Man, some of what you said I knew but a lot I wasn't aware of. The plumbing aspect will get taken care of in the new shop. For now I run a 50' hose from a portable (20 gal) compressor. I do run a filter at the end of the hose with a final 12' hose to the gun.

I suspect my trouble was a combinatio of humidity and pressure/mixture. Just going to take some practice and experience to get it right.

Tony, I stopped by the store to get some retartder for the next coat and wound up with a product like you linked to. Worked like a charm!

[cbrown]

I love Resisthane. A water based pre-catalyzed lacquer. Available from Hood finishing for about $35/gallon delivered. I do not know nearly as much as Cabinetman just said but I have not been unable to mess up Resisthane. It can be used as a sealer so you do not need anything else. You can also brush it if you want for touch up on on small parts. It dries so fast you may have difficulty brushing large stuff. I am using white Resisthane currently on plantation shutters. I previously used clear gloss. Both work for me. I know the clear is rated for kitchen cabinets, I don't know about the tinted but that is probably not what you are doing.

Jim

I am interested in white Resisthane for a cabinet project. I have found the Hood site but no application instructions online. Have you been using their primer? How many topcoats for coverage?

Thanks,

Chris

[JimD]

On the first set of shutters I did not use a primer. I had to cut the completed shutters, however, to fit them to the opening. I primed the cut with Kilz - the latex kind, not the original - only because that is what I had on-hand. I then put a couple coats of Resisthane on top of the Kilz. It went fine. I am working on the next shutters now and will prime the louvers and frame with Kilz before applying the Resisthane. Resisthane is very thin - like lacquer is - so it does not help hide any imperfections in the surface. I think priming first will result in a smoother final finish but I am not far enough long to know for sure.

I would not be afraid to use Hood's primer but my experience suggests which primer is not critical. The instructions on the can say you can apply Resisthane over any finish that is completely dry. Clear resisthane is recommended to be used without sanding sealer but primer is recommended under tinted resisthane. The tinted resisthane is not as tinted as normal white paint. It will not "cover" with one coat. Most of my louvers are mdf and the first coat of resisthane did not make the mdf white. Three coats did, however. One coat of primer makes them white.

Jim

[cbrown]

Clear resisthane is recommended to be used without sanding sealer but primer is recommended under tinted resisthane. The tinted resisthane is not as tinted as normal white paint. It will not "cover" with one coat. Most of my louvers are mdf and the first coat of resisthane did not make the mdf white. Three coats did, however. One coat of primer makes them white.
Jim

Thanks! I don't suppose you have pictures of your shutters you'd like to share?

Chris