Cleaning Guns When Spraying Waterbornes
Hot soapy water, then alcohol or acetone for drying (and don't let it stand around). October 14, 2006
Question
I am spraying waterbased wood finishing products with a Sata HVLP KLC finishing gun. What is the best way to clean the gun? I am new to using waterbased products.
Forum Responses
(Finishing Forum)
From contributor A:
As soon as you've finished working, empty the spray gun, rinse with hot water, then warm, soapy water - which you should spray through the gun - followed by a plain water rinse. Use a final rinse/spray with either acetone or 90% isopropyl alcohol to dry out the gun. If you're spraying waterbased materials, you should be using a gun with 100% SS wetted parts, such as the needle and nozzle - I presume the Sata is. I usually disassemble the wetted parts – needle, nozzle, air cap - and inspect the internal wetted passages, and check if they are clean. Build-up of many waterbased finishes in internal passages can be removed with epoxy thinner or a special waterbased materials gun cleaner usually available from the spray material manufacturer. Waterbased materials can be difficult to remove if left in the gun very long. I also find they tend to build up on the nozzle during spraying, and can clog the small atomizing jets in the air cap. I keep a damp sponge or cloth handy during spraying to remove this build up while working.
From contributor B:
Your gun is a gravity feed, I believe. Although contributor A’s regimen is very thorough, I’d say it's overkill. I have several different types of guns including pressure pot, cup, and gravity feed (three are SATA). The wetted parts must be stainless steel or aluminum or plastic (the cups). You must clean your gun as soon as you're done spraying. I don't even let finish sit in the gun if I'm just taking a break of a half hour or more. This is more important with a remote pressurized pot. With my gravity guns, I empty the remaining finish then flush it all with warm water. I take everything apart and flush and brush all the orifices. Don't use abrasive pads (similar to the "un" steelwool pads) on the cup or you'll just provide a rough surface for finish to stick to. If I get dried finish on any part of my gun, I use Lacquer thinner to soak it off. Then I use soap and water to clean, and water to rinse. When I'm all done, I blow out all the orifices with compressed air. This last step may be a bad idea as there is the possibility to contaminate the gun with compressor oil.
From contributor C:
I would only add that I use ammonia and water to clean the gun with. I use a #10 Accuspray gun with Enduro finishes and am happy with it.
