Very true. Temperature, humidity, and thickness of application may
have as much to do with your finish as anything, but fine tuning your
tip for actual use is just as important. You can spray with the wrong
tip (say the 2mm for lacquer) and get away with it. Likewise, you can
shoot a low color saturated latex with a 1.2 tip and get away with it
if you thin enough.
If it were me, and sometimes it is, I would hit that 2# shellac one
more time and cut it about 20 - 25% depending on the weather. The
hotter, the less I would thin. I prefer a smaller tip and use a 1.2
mm on my gun, but doubtful you would find any difference. I like to
shoot it thin, just thick enough to hang onto a vertical surface. The
finer tip will put out a finer finish.
As for BIN, I shoot that unthinned out of my gun with a 1.5 tip, and
have shot it with my 1.2 tip as well. A call to Zinsser revealed that
they put in some kind of agents that make it more viscous in the
application than homemade shellac, and they told me that it was
formulated with the knowledge and intent that it would be gun
applied. It is one of the few materials I just pour in the gun and
It's easy. The preferred application thickness for almost all top
coat clear (including shellac) materials sprayed is 3 mil. Odd, but
it holds true for just about anything I have ever seen. You can apply
more if you want, but 3 mil is the standard. So what does 3 mil look
like? Pull out a dollar bill and check out its thickness.... right at
So spray some finish on a test board, take a razor blade and cleanly
scrape away a side so you can see a profile and compare it to your
dollar. Personally, I have never even used a gauge.
You can shoot most latex finishes thicker, and certainly 5 mil is
within that range. For that, I use my 2 mil tip, and during our hot
summers I shoot that unthinned. For more moderate weather, say the
70s, I thin latex about 20%, then shoot it with my 1.8 mil tip. Even
though you don't have to thin latex with a 4 stage turbine or a CAS
gun, it works better for getting a finer finish.
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