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Paint gun cleaning and disposal

coffeeguy

Well Known Member
I started my build priming with Stewarts waterbourne primer. It worked well for what I needed it for and I could use it in my basement in the winter. I've switched to SPI expoxy primer for some of the exterior pieces and it's not as easy to use, but not that bad.

My question is how exactly do you go about cleaning the gun afterwards? With the Stewarts it was water, a good brushing and finish with running some water thru it with the air hose connected. For epoxy I've been using Lacquer thinner, but I've heard of people using acetone. Also saw and EAA hints for the homebuilder that suggests shooting carb cleaner into the gun.

The mechanics... Take the gun off the hose, maybe a little paint left in the cup. PPS cups, toss? let dry? On a bench, on the garage floor? I don't want acetone to soak into a wood bench. Run the some acetone or lacquer thinner thru the gun, take it apart. What about the stuff that runs out? do you clean it out in a plastic or metal pan/bucket? reuse any acetone for the first clean?

I've got a can of paint and thinner leftovers from earlier cleaning, but not sure I want to use it for anything other than to capture stuff coming out of the gun. detailed cleaning -anything special? Do you shoot thinner thru the gun with air? At what? I have big cardboard sheets, but shooting a flammable liquid on cardboard and keeping them in my garage even short term seems unsafe.

These questions are ones that no one talks alot about, advice or pointers to youtube videos are appreciated too. It's probably not as complicated as I think it is, but want to make sure I get my gun clean and keep it that way.
 
For cleaning the gun internals lacquer thinner, acetone, or MEK will all work. Currently I’m using lacquer thinner. I fill a spray bottle with thinner then spray into the top of the gun. Dirty thinner will come out the fluid tip and into a 1 gallon empty paint can. Keep spraying and working the trigger until the thinner comes out clean. Take off the air cap and clean the inside. Pull the fluid needle and make sure it’s nice a clean. Spray thinner into the top again. Spray some thinner on the outside and wipe with a rag or paper towel.

Used pps cups sit on the counter until they harden then get trashed. The 1 gallon can I put my cleaning waste in I use until it’s about 1/3 full then it gets to sit until it hardens. If I have a larger amount of paint waste it gets poured into a 55 gallon drum and a waste company picks it up when full.
 
The spray paints that I'm using include etch primer, epoxy primer and 2K polyurethane top coat. Any leftover paint or thinner from cleaning gets tipped into a slops bucket that is part filled with sand. I put it outside to evaporate/dry and will take it for disposal eventually.

First step after painting is to put some gun wash in the cup and swirl it around to clean the cup. Tip this into the bucket and wipe out with a paper towel. Then some more gun wash in the cup and pull the trigger over the bucket so it dribbles out and starts to run. Then hook it up to compressor and spray outdoors onto newspaper. The gun wash comes from the paint store and is a blend of solvents intended for that purpose.

Once initial cleaning out is done I put some more gun wash in the cup and let it sit a few minutes and then drain through the nozzle. This doesn't require air. Finally, I disassemble the air cap, needle and fluid tip and clean out the chamber with gun wash and the cleaning brushes that came with the gun. Then I put it back together and spray some clean gun wash through and leave the lid off the cup to dry out.

It takes about 20 minutes to clean up. If the gun is not properly cleaned then the next time that it gets used there can be contamination in the spray that ruins the job.
 
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I use lacquer thinner. Run some LT through the gun for initial cleaning then fully disassemble gun and clean all parts with LT in your mixing cup. When using high build primer, be sure to clean the internal areas of the gun itself else you will get undesired buildup. This is why the pros tend to have a second gun used exclusively for high build primers. I just dump the LT in an area of the yard with no grass. It is not that flammable and evaporates very quickly.

Larry
 
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Cleaning

Like Larry ^ says.
The only way to get a gun completely clean is diassembly. The fluid might come out clean but there's stuff inside just waiting to cure and ruin a paint job. Must be the name. :D

Here's my process.
3M PPS or similar eliminates cleaning the cup.
A few old cans are handy.
Mark the controls and count turns to repeat settings.

Disconnect air
Flip the gun and pull the trigger. It allows paint to run back into the cup.
Remove the cup
Fill the gun with a solvent. Acetone or Lacquer thinner.
Grab a stack of Q-tips and use one to slosh the paint loose
Trigger to release into a can.
Repeat.
Disassemble the nozzle, tip and needle. Place in a clean can. Add solvent to soak.
Finish cleaning the gun with q-tips and an acid brush then wipe with paper towel with solvent.
Clean the parts in the order they get reinstalled. It's important to clean the inside of the tip carefully. Paint builds up in the tip and a flush won't remove it. Inspect each part before reinstalling it.
Pour in solvent and blow it out.
Install a fresh cup and set the controls.

I use rubberless syringes to suck paint out of the can and to measure chems so the cleaning solvents make a pass through the paint syringe to clean it before going into a bucket of cat litter to evaporate. Always use clean solvent for the last pass.

3M PPS cups have a cap. If I expect to need the paint for touch up in a day or two, I collapse the cup removing air and cap. It's only good a couple days. Then I pour cat litter in the cup and leave it uncapped to set up. Dispose properly.
 
Thanks guys, Not too far off from what I've been doing on my first few batches of expoxy. Appreciate the help.
 
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