Cleaning a Spraygun when Changing from Solventborne to Waterborne Formulas

Advice on cleaning an air-assisted airless spraygun before converting to waterbornes. April 16, 2010

Question
I'm switching back to waterbase products after a few years of spraying solvent precat. I've got Fuhr 380 coming to the shop soon and I would like to get my Kremlin system prepped to spray it. I figure a good flush with lacquer thinner, a gallon or so, and then change out all filters I can get to, run denatured alcohol through, and then flush with a lot of water would be good. Any advice on what tip to use? I think I have the smallest tip available in the gun now. If anyone has done this can you please give your schedule for doing it?

Forum Responses
(Finishing Forum)
From contributor G:
I would go with acetone in place of the alcohol and then use some water cut with the Fuhr universal cleaner. Your tip size should be about the same. Just make sure you watch for build up as you spray, I keep a brass brush handy to knock the build up off. Then you should be good to go. Also, for what it’s worth, I really like the 345 finish, especially the dull. It has a wax component that is very close to a solvent look. I've been spraying Fuhr exclusively for about a year and a half now, I will never go back.

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From contributor C:
I too use FUHR, nearly six years now. The 380 is a near water clear, the 345 does have the wax feel and is very clear as well but I think for the clear over the 9200 use 380. Check with your supplier for the tip sizes but the products do act very similar to solvent as far as spraying goes. I have had reason to use solvents and clean with thinner and flush with water and no problems.

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From contributor D:
I flush mine with lacquer thinner and then run hot water through it and it’s ready to go. A gallon of thinner seems pretty wasteful. Just pump it all dry on low pressure, flush it with a half gallon, open it up and flush the filters and it’ll good to go. I do this sometimes three times a week.

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From contributor W:
If switching over from solvent-based to water-based, flush your pump, hoses and gun with the corresponding thinner that is used to clean out the solvent finish that is currently in the system. Follow up with denatured alcohol, then warm water. You should then be good to go.

I use a 11/1000th tip set in my MVX gun, with the Kremlin 10:14 pump set at 20psi on the fluid pressure and 20psi set at the atomization pressure when spraying Target coatings EM6000 Lacquer. Move up to a 14/1000th if you plan on spraying their EM2000wvx. Keep the same settings. Shoots like glass.

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From contributor O:
This always worked for us:

Solvent to water: lacquer thinner, acetone, water, coating

Water to solvent: water, acetone, lacquer thinner (probably redundant) coating.

Fuhr told us their cleaner will cause fish-eye. But if you're cleaning regularly you shouldn't really ever need to flush with it anyway - just soaking the gun etc. Kremlin makes a "Bubble Buster" tip specifically for waterbornes.