I've got my spray gun

[Brookside]

You were all very helpful in my selection of a spray gun. I went with the Sata mini-jet which just arrived. I've read the operating instructions and I'm preparing to begin my finishing journey. I just wanted to throw out a couple more specific questions regarding technique. I do intend to experiment but some general starting points would be helpful.

There are three adjustment knobs. The first is the "Infinitely variable round/flat spray control." Any suggestions with where to begin with this setting would be appreciated.

The second is the "fluid adjustment knob." Probably hard to describe how you set this, however, if you have any input I'm all ears.

The last is the "air micrometer". Maximum to minimum; any thoughts?

I'm using the spray laquer from the Luthiers Mercantile. How much do you cut it and with what exactly? Any tips on spraying technique? How do you spray under the fretboard extender and in the tight scroll regions?

Thanks again to all who responed to my spray gun selection questions. I know I've got a good one, it's just a matter of getting good at using it. I'm sure that will come with practice.

[sunburst]

You will not want your spray pattern round. Try starting out with a slightly eliptical pattern, almost a line, not almost a circle. To see what your pattern is, put some kind of paint in there and spray a short blast at a scrap surface without moving the gun. The shape of the paint spot is your spray pattern. You'll have to see what exact pattern works best for you through experience, but that should give you a starting point.

The fluid adjustment knob controls the amount of fluid (paint, lacquer) that comes out. Too little and you have a dry, orange peel like surface, too much and you have sags and runs.

Tha above adjustments are all dependant on the viscosity of your fluid, so put the amount of thinner in that gives you the correct viscosity. I realize that's pretty nonspecific, but hopefully someone will chime in that can tell you what you need for your set-up (tip size etc.) and how to measure with a viscosity meter.

As for the scroll and extender, the tradition is to pretty much ignore those areas and let whatever dusty finish that makes it in there be.
I try to shoot some in there by spraying quick bursts from a rapidly moving gut at close range before spraying the rest of the top. That way, I can see where the finish has accumulated on the top and avoid those areas as I spray the rest of the top to get an even coat. If I wait to spray those areas until after spraying a smooth coat on the top, I'll likely get sags or runs, or at the least, areas of thicker finish on the top.

I use a slow lacquer thinner, and usually a little retarder. It's humid here a lot of the time, so I got the retarder to help control blush, and I find that it lets me spray smoother, thinner coats by letting the lacquer flow a little longer.

I assume that the "air micrometer" is your air control. If so, it adjusts the amount if air that you get with the triger pulled all the way. Experiment, you'll figure it out.

Good luck, have fun!

[Jim Hilburn]

I've found you can hand paint lacquer with retarder in it down in the scroll and under the extension, and you can melt in some of the overspray, but it will still be lumpy, not as smooth as where you can buff it, just not as crystilized.

[Michael Lewis]

Cut out a piece of plywood or something similar in the basic shape of your mandolin, and practice on this. #Let it dry and scrape off most of the build up, sand it and do it again, and again, . . .

You will develop a feel for what you need to do. #About the spray patern, as Sunburst said, make it an oval, not round, and use it like you would use the wide side of a brush and place strokes on your "target" by making a pass, then come back and put the center of your spray pattern on the edge of what you just sprayed. #Continue this pattern of overlapping passes until you have covered the "target". #Always try to spray on the "wet edge" to keep the surface smooth and even. #Just practice a bunch. #Once you get it it's pretty easy.

[thistle3585]

I'm a woodworker and spray a lot of laquer on furniture, but have never attempted an instrument, so I'm no expert there. I do suggest working on your "technique".
Always keep the the spray gun perpendicular to the surface. When moving the gun back and forth keep its path parallel to the surface and not in an arc. Don't use your wrist, use your arm. Your arm should remain perpendicular to piece. This will prevent irregular spray patterns.
When spraying, trigger the gun before moving into the piece and untrigger it once your off the piece. Most people want to trigger it where they want to start, but this can cause build up and runs.
Usually, it is hard to distinguish the spray pattern, or err, on the first coat or two. This is because the substrate is soaking up the material. Technique will be more critical as the surface builds.
There is lots of reading on spray gun technique.
Good Luck.

[Brookside]

Thank you gentlemen. I was just nervous. I soon realized that it would be hard to make a huge mistake with this spray equipment. Once I got into it I started to feel pretty good about it. Seeing the colors jump out at me was one of those magical moments in lutherie.