Cleaning a Neglected Spraygun

      Advice on salvaging a spraygun that is all gunked up with dried-on polyurethane finish. April 21, 2008

My brother used my HVLP gun and returned it last week with latex white poly still in the cup, and the gun must have sat for at least a month uncleaned. Does anyone have advice for reviving this gun? I put the turbine on and nothing comes out (no surprises there).

Forum Responses
(Finishing Forum)
From contributor B:
Soak it in alcohol or lacquer thinner.

From contributor C:
Is it latex *and* white polyurethane or latexwhitepoly?

From the original questioner:
It is Enduro white polyurethane. Does it need a rebuild kit or just selective maintenance?

From contributor C:
Soaking it in methlene chloride - 90% and methanol - 10% will loosen and remove the urethane. Let soak overnight. Remove any aluminum parts if possible - cup, etc.

From contributor E:
Does methlene chloride have a trade name that someone at a paint store might recognize, i.e. MEK or epoxy thinner, etc?

From contributor C:
You can just buy methyline chloride stripper for paint - Kwick Clean, or other. If you do, make sure you run toluene through it after it's clean to get rid of any wax that's in the stripper. Do it a few times and then wipe all the parts with lacquer thinner. Let dry, re-assemble. I used to buy straight MC and methanol from Sherwin Williams industrial paint stores. That way I did not have to worry about the wax. If you do that, make sure you keep the bucket covered to lessen evaporation. Wear gloves also - nasty stuff!

From contributor G:
I've also found straight methylene chloride at the plastics shop. It is used to bond sheets of plastic.

From contributor P:
Remove the air-cap, air nozzle, and fluid needle from the spray gun. Try to clean the fluid passage in the spray gun using a tube brush (one should have come with the spray gun) and lacquer thinner or acetone. Run the brush through the front of the gun as well as the pick-up tube. You may need to remove the pick-up tube from the spray gun to get the brush to go all the way through.

Fill the spray cup with solvent and let it soak. Then use a cloth or paper towels to clean it out. If the finish hasn't hardened completely, lacquer thinner or acetone will work. If the finish has hardened/cured inside the fluid passages or cup, using a liquid paint and varnish remover that contains methylene chloride is a good idea.

But since the spray gun has a plastic body, it may not be a good idea to soak the whole thing in any solvent. More than likely the manual recommends disassembling the two halves of the spray gun and removing the metal fluid section and soaking it separately. Be careful not to lose or damage the thin rubber gasket pieces that seal the two halves of the spray gun.

From contributor J:
My advice would be to not loan tools.

From the original questioner:
Thanks for the tips. I'll start the cleaning process this weekend. Luckily I have two other guns to use. By the way, contributor J, my 6 year old daughter offered up the same advice you did. Glad to see good advice spans the generations. ;)

From contributor D:
I have an accuspray #10. Take screws out, spilt gun in half, take all rubber gaskets off, soak metal parts in liquid paint remover, not semi-paste, wash with lacquer thinner.

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