Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum some lacquer spraying questions...

Yes, My mistake, going too fast I should have explained that one better. Orange peel is caused by the surface drying prematurely without having the product flow properly previous to it setting on the outer surface. Usually this happens during hot weather and to slow the drying time butyl cellosolve is used.

Yes if the atoms dry before contacting the board most will bounce away but some will attach as you say and feel like sandpaper. Sometimes this can happen with over spray if a fresh board is left close to the spray area…

Pre cat nitro is lacquer with a catalyst already in. This causes the lacquer to be more brittle when dry. There is also nitro where you can add the cat manually, but too much cat will cause cracking in the finish later; not checking or crinkles but long cracks like pond ice.

Pre cat lacquer for brass instruments is a lacquer for metal which is slightly different than furniture lacquer. I use that for the continuous hinges, pedals, and other dress metal components.

Thanks, Dan but my guess is that Nitro is just drying, at air contact without any catalyse.

catalyse is for polyurethane, polyester, 2 active composants.

Now may be I do not get what mean catalyse. (may be air/solvents or other products contained in the lacquer create a catalyse)

I just read that with a good spraying setup and product, some of the extra mist is just absorbed by the surface and mix with the rest.

With HVLP guns (on a real compressor) the distance for spraying is short, around a non extended hand, really small.

This is to make obtain some force of projection, as it level the spray.

Also there is an air cone around the spray (which is what drives the paint) and the force of that air is not strong, the shape of the spray nay easily deform if too large distance is used.

There are very good informations on how to calibrate and verify the "brush" shape with HVLP or other guns, on the SATA Web site.

They even propose to use sampling the spraying test at a given distance, on an adapted surface, served me well to detect if my gun and product where correctly prepared.

A gun with integrated manometer is the best, but even a small one on the air entry helps a lot, as pressure lower in the tubing, and a really precise one is necessary for the effect to happen.

Nitro had to be diluted 0-15 % under hot Conditions. But with a high grade solvent (something against moisture is in the solvent).

It is amazing that even on cars, that look very shiny, when you look closely the lacquer is more textured that what could be allowed on a piano.

(even on some polyester high gloss some spraying texture is visible).

Possibly lacquers that can be polished are better for high gloss 'mirror finish'

Mr. Silverwood, Mr. Oleg, it was very kind of you to explain all these details.
I too learned a few things, and got some information reinforced as well.

Best wishes-

Hi all - After reading this thread from beginning to end about all the trials and tribulations of applying a sprayed on finish, all I can say is thank God we brush on every finish we apply. One 1 1/2" brush, 1 can Minwax gloss, 1 can semi-gloss and 1 can satin, and it's a done deal. More elbow grease, to be sure, but far fewer headaches. And no drips, runs or orange peel.

O.T., Bernard, congrats on the Hawkeye win today (assuming you're a football fan) - good luck to the Hawks in Ames next week. If you happen to be going to the game, stop by in Boone - 14 minutes from Jack Trice stadium, and see an example of the finish we put on in our shop.

Best wishes, all. Chuck Behm

What is the Humidity level ? Nitrocellulose has a danger zone above 65%. My spray booth is climate controlled, 400 sqft of filter area with two 48 inch stack fans but even if there is high humidity outdoors I still wont paint if the humidity is above 70% .

Bubbles could be a problem from an improperly sealed surface and you may have to add some blush retarder if you get any grey hues along with bubbles. Shellac can be used as a sealer too and will seal over silicone impurities.

An electric HVLP set up could cause issues in that they use hot air to propel the material. I use 3 main guns at the shop. One older dinosaur Turbinaire ( Canadian) 3 stage HVLP which is great in that you can spray lines down to 1/16th of an inch wide but we use it for Acrylic Enamel only

The other is a Earlex which is non adjustable ( Primer only)

The third is a Devilbiss top cup air gun. I use a digital meter at the gun set at 23 - 28 psi with 120 lbs of line pressure. I think there is 200 feet of iron pipe between the air hook up and the compressor with 3 different moisture traps and I can still be the Mad Scientist to get dialed in on certain nights.

I do all my painting at night no matter what time of year

You mean you brush shellac and alcohol as a sealer ?

If you spray this is yet a mix with cellulose and de waxed, that may accept Nitro more easily.