Gun Cleaning Solvents for Waterborne Finishes

Finishers recommend cleaning solutions that will cut waterbornes. March 26, 2009

Are there any experienced general finishes users out there? What is the best solvent (regardless of toxicity, but still readily available) for clean up and flushing my gravity feed cup gun (Fuji-true HVLP with an aluminum gup)? It's a good little gun for switching between different finishes like when making up a sample. I normally use either lacquer thinner or acetone - but I'm still getting some contamination unless I take the whole thing apart. It mostly happens when I go from their white (tinted) acrylic to their clear poly.

Forum Responses
(Finishing Forum)
From contributor A:
Waterborne products are usually pretty easy to cleanup unless they are catalyzed. We usually just use a water rinse followed by denatured alcohol. Occasionally we will run acetone through the gun. Thatís every waterborne we've ever used. Diluted ammonia should tear it up pretty good as well. I would stay away from lacquer thinner, it may have enough oil in it to contaminate.

From contributor B:
When switching between water and solvent-based coatings do this:
1. Flush with water
2. Flush with Acetone
3. Flush with Lacquer Thinner

Your gun should be clean and ready for use on your solvent-based jobs. To go back to waterbased, simply reverse the procedure.

From contributor T:
General Finishes Brush & Gun Cleaner for waterbase products. Flush and clean equipment follow with hot water.

From contributor A:
I don't understand the lacquer thinner before spraying solvent borne. I agree after spraying. The acetone shouldn't bother anything it's about as clean a solvent available.

From contributor J:
I always rinse with warm water, gets rid of everything if done right away. If it's been in the gun awhile (a day or more) I'll break the gun down and give it a better cleaning. I went to waterbase to avoid spraying solvents. It seems kind of backwards to use them to clean up after? Although I do admit once in a great while I give the guns and cups a good bath in lacquer thinner to get any build-up off.

From contributor W:
I flush my equipment with water and denatured alcohol at the end of every workday. I also soak my air cap in a sealed jar of denatured alcohol. These two procedures keep my lines clean and running free. If you use a high pH cleaner such as a "Gun Wash" ensure that you rinse out the lines with a fresh water/alcohol solution. High pH cleaners will create problems if not flushed.

From contributor A:
I think it is unrealistic to completely eliminate the use of solvents when using plastics to coat wood. Switching from mineral spirits, lacquer thinner, acetone, naptha, and occasionally some proprietary highly toxic concoction to H2O and denatured alcohol seems like a fair compromise.

From the original questioner:
Iím kind of surprised that no one mentioned any of the "exotic" solvents like eyxlene or M.E.K. The reason I asked specifically if any "general finishes" users had any thoughts was because I had a bit of a bad experience recently. I started spraying some GF white undercoater and needed to thin it down a bit so I used some denatured alcohol (which I read about on this forum and used successfully with some wb clears). It actually coagulated the undercoat into a gelatinous blob in a few minutes!! Quite the mess to clean up Ė Iím just glad it wasn't in my airless! It got me thinking about using d.a. for clean up which I've been doing with my clears (non GF).

From contributor N:
Almost all waterborne finishes are sensitive to basic solutions. A.K.A Ammonia. Water and 20% household ammonia will rip through almost all waterbornes I've ever come across.

From contributor F:
We use a product called Acrastrip. It's actually a paint stripper that is cut 1 to 1 with water. We buy if from Sherwin Williams.