Adjusting the Spraygun for Pigmented CV

Finishers discuss good pressure for a spraygun, how to dial in a good setting, and how to adjust chemicals for better results. March 16, 2015

Question (WOODWEB Member) :
What do you all recommend setting my spray equipment at for spraying pigmented CV paint? I have an air assisted pump with HVLP pistol. I've been running on average 25-30# fluid pressure and 30-40# air. I thin my mix to get a good flow rate and it looks great but it feels like it is just too much pressure, too much overspray, etc. When I back it all down then it orange peels easily, and I only go down a few pounds. What does everyone else spray at?

Forum Responses
(Finishing Forum)
From contributor C:
An average air assisted pump puts out 10 psi per 1 psi of air so at 30 psi to the pump you will have 300 psi fluid going to your gun. You should be using an AAA gun and high pressure hoses. HVLP means high volume low pressure. For a pressure fed HVLP gun I use less than 10 psi for fluid pressure.

From the original questioner:
I am using a Binks AA1500 pistol. When I try to lower the fluid pressure to below 20 I get lousy results. It orange peels or at the very least takes a much longer time to spray one door. Also I am using a 114-01310 Binks tip.

From contributor C:
Set the fluid pressure to 35 psi. Turn off the air supply to the gun and pull the trigger. You will notice two tails on the spray fan - turn up the air until the tails disappear. It should be around 20 psi.

From contributor N:
What ratio is your pump? The answer to this question makes a world of difference; for instance if you have a 10:1 and you have the air to the pump set at 40lbs that's 400 psi at the gun, a 20:1 at the same 40lbs would be 800psi at the tip. The same doesn't hold true for the atomizing air to the gun what you set at is what you get (remember to set the pressure for what you want with the trigger pulled, that way you know what you have under working conditions). Generally speaking in my experience most finishes are sprayed between 400-800 psi fluid and 15-25 psi atomizing air. But really the best way to set this is to forget the gauges and just slowly turn the fluid pressure up until you have a fairly well developed spray pattern but with defined tails and then slowly add atomizing air until the tails are gone.

From the original questioner:
Thanks for the help. I will check my pump ratio for sure. That makes sense to me. I do set up by feel more than I do by-the-numbers, but I noticed to get a good flow using conversion varnish I felt like my numbers might be a little too high. I get a good finish this way just puts out a lot of product. I am accustomed to spraying with electric airless pumps atomizing at 1500 psi so this is a learning curve for sure.

From contributor S:
I'm not familiar with Binks orfice size on their tips but if itís in the realm of a standard size and not to small then you should be able to spray your CV at around 300 psi depending on your pump ratio and 10-15 psi on the air side. Taylor your chemicals to do the rest. Do you just need to reduce with butyl acetate a bit to get it to flow or do you need to slow down the initial flash off a bit with butyl cellosolve at around 5% or a cocktail of both? Get your standard setting and use your chemicals to make it lay out like you want. Temperature, humidity and air flow all effect how your coating will act.

From contributor U:
Itís not so much the pressure as the reduction and the proper reducer. I spray all ICA for paint and I usually thin 100% with a moderately slow reducer.