Keeping the Gun Clean with Waterborne Finishes

Easy routines to keep your spraygun from accumulating dried-on finish at the tip. December 23, 2014

Question (WOODWEB Member) :
Iím having a problem with water based finishes collecting and drying on the air cap while I spray. Iím new to water based finishes and pretty new to finishing in general. Has anyone else had problems like this before? Iím using a kremlin 10.14 pump and a MVX gun and spraying General Finishes Clear Poly. Iím also having a hard time removing the dried finish from the gun, nothing really seems to break it down. Does anyone know of a good solvent? Iíve heard a lot about these ultrasonic cleaners. Has anyone ever tried to use one to try to clean your gun and tips?

Forum Responses
(Finishing Forum)
From contributor K:
The Ultrasonics work great! If youíre getting material build up on your tip itís going to be a bad O ring allowing material to come out through your atomization holes. Take the cap off and replace the white O rings (thereís one on the fluid nozzle and one in the spray tip).

From contributor N:
I've gone over to the pot and gun for WB's.That very frustrating dried blob on the tip happens way less, you get less micro bubbling and a more attractive finish as well IMHO. As for cleaning your gun during and after use I've found Dirt-Tex (ammonia cleaner) works great. Spray it on and wipe it off at noon and the end of the day and your gun will look like new. I also use it to clean the needle, nozzle, air cap and fluid passage when I break down the gun for a thorough cleaning.

From Contributor H:
On my HVLP turbine gun I find it necessary to sometimes flick off crud which might have dried on the tip of my gun in order to keep spraying and I do use General Finishes. I recently bought some spray gun cleaner made by Krudcutter cleaner on sale and that stuff is totally wonderful. I used to use lacquer thinner. I have found that a big box of strainers from Harbor Freight and the dipping the tip of my gun into a small container while propping it up is sufficient to get amazing results.

From Contributor P:
I'm having these same cleaning problems as I only spray water based lacquers. The clear isn't too bad to clean up but I am much more frequently having to clean my gun when spraying the pigmented stuff. Is anyone using a mixture of ammonia and water? I read on WOODWEB in some older posts that a 20% ammonia to water ratio should work well. I've been trying it on this current job in my shop and find its working only as well as methanol which is what I normally use. I've been thinking of bumping it up to 40% but the 20% ratio has already caused my air cap to go from shiny silver to a grey metal colo, and there is a plastic retainer ring in the air cap that I'm not sure how well it will handle stronger ammonia. The nice thing about ammonia is it is much cheaper than methanol. I'm using a Devilbiss gravity cup Trans-Tech gun for clarification - a beautiful finishing gun.

From Contributor P:
Just a little update - I decided to try a 30% mixture of ammonia and it must have been over the necessary threshold because the water based finish lifts off of the gun parts in this 30% solution much easier. Who'd have thought there was so much to be gained from an extra 10%. Iím still not certain if this is safe for all or some of the guns parts. If anyone that can shed light on this I would be grateful.

From Contributor P:
Update on the ammonia: After a few days of using it I have switched back to alcohol. The ammonia trashes the appearance of the gun and I went through a set of seals. Maybe a coincidence, but Iím betting not.