Tip Sizes for Mini Spray Guns

A few observations on spray-gun tip size equivalancies (it's the viscosity that most affects nozzle choice). December 15, 2005

Question
I am thinking of switching from my Astro (full-sized) HVLP DX series gun to a Sata MiniJet. I am using a 1.3 and a 1.5 tip with the Astro (for Fuhr and Target WB lacquers) and getting excellent results.

My question is: What size tip would be equivalent on a mini HVLP gun? This is for spraying stringed instruments with a smaller compressor, and I don't need a full-size gun. In fact, I'd actually prefer to go to the mini for the lower air consumption and the potential for finer detail work.

Forum Responses
(Finishing Forum)
From Paul Snyder, forum technical advisor:
The size of the needle/nozzle is based on the viscosity of the finish and whether the spray gun is siphon feed, gravity feed, or pressure feed. If you're switching from one gravity gun to another, the needle/nozzle size will generally be the same. It may be slightly different based on the atomizing ability of the gun. The manufacturer should have a chart that recommends the needle/nozzle size for their spray gun based on the viscosity of the finish you're spraying.


From contributor D:
It's a little hard to answer your question and doubly hard since waterbornes vary so much in viscosity. The mini Astro with the 1.2 should do the job just fine and the Mini Astro with the 1.0 might do the job depending upon the viscosity of the waterborne that your using.

Generao Finishes' Pro Acrylic goes through the 1.0 just fine. Fuhr's waterbornes are a bit too thick for it and require the 1.2. Lacquer is lacquer, but with waterbornes there is so much variability. The beauty of the Astro however is that extra needle/nozzle sets are not very expensive. Nobody has ever said that for the SATA.

A new development on the MiniJet front is that SATA has released a 1.4mm nozzle set for the MiniJet 4. I'm using this to paint urethane bumpers on cars as it puts out a fair amount of paint.

The best recommendation is to measure the viscosity of the material and then call DanAm (the American SATA distributor) and provide them with that information and let them make a nozzle recommendation.