View Full Version : spray gun cleaning
04-06-2007, 01:00 PM
I've read the gun cleaning as outlined on this site, and I have a few questions.. If I use the cup liners with my Dev plus gun, when I'm done if I remove that liner and then put thinner in the cup and spray until the thinner runs clean, and then do it again, and then remove the air cap and do it yet again, then soak the air cap in thinner, then blow compressed air through and around all those little holes in the air cap, then reassemble and blow more thinner through it for good measure, then run the gun dry and blow some more air through it, why does it need to be disassembled? It seems to me that anywhere the paint could go, the thinner will also go.. Is there really a need to take it apart all the time? Seems to me that I will put a lot of unneeded stress on o-rings and seals if I pull it apart all the time.. PLEASE comment.. Mike
04-06-2007, 02:25 PM
It may seem like its more trouble to take apart but the way your doing it uses way more thinner than i would and also taking it apart just insures me that theres not a speck of anything left in there to fly into my paint. I would rather take one apart then to keep running thinner through it many times. You might get away with the base but I would def. do a tear down when it comes to primer or clear..... Just my opinion.
04-06-2007, 03:17 PM
Just do the test. Spray some primer or urethane, then do your spray cleaning...then take it appart and you will see that there was stuff left in there.
I know alot of guys that simply run thinner through a few times then put some thinner in the cup and then leave the air cap in the cup, in the thinner until the next day. Their gun is always wet this way. In a production shop, you might not want to take the time to dismantle everything all the time but in my custom painting context it pays to do it.
It's a drag to have one little piece of silver metalic, even minute being spit in the middle of a black hood...
Dennis N. Schmidt
04-06-2007, 04:13 PM
You disassemble in order to be able to brush off residue. Serge hit the nail on the head. Do it your way after you have shot basecoat or primer and look inside of the fluid tip. You will find it coated with either the basecoat or primer. These will only come off it you brush them off using mechanical abrasion (a nylon brush).
04-06-2007, 06:59 PM
I took my gun apart an hour ago, and inside was a thin, very thin layer of red paint!! Just a touch with a soft nylon brush and thinner and it came off. As always, thanks for the advice... MikeP
04-06-2007, 07:01 PM
While I agree that the gun should be disassembled after each use for a proper cleaning (I do so myself), and once you get into the habit, it becomes a quick easy routine.
Having said that, one thing you can do along the way to help in the cleaning process, is to "percolate" some solvent through the gun (I'm sure a search through the archives will turn up plenty of discussion on the matter, and I'll leave it at).
But, basically, after you've sprayed what you need and poured out any excess, you do the following. Turn the air PSI to the gun way down (5 is enough), pour in just enough solvent to fill up the head of the gun, so there is just a hint of it at the very bottom of the cup (assuming you're using gravity feed). Next, place a paper towel over the head of the gun (covering the fluid outlet, and air cap orifices if you like). Aim the gun away from you or anything you don't want to risk getting splashed (you can opt to replace the cup lid, just be sure the PSI is down or you're likely to launch the lid). Pull the trigger and let it percolate in the gun (bubbling and boiling). Remove the paper towel from the nozzle, shoot some remaining thinner straight, and repeat a few times.
Now, taking it all apart is the surefire way to gurantee you've got everything out...but if you perform this step beforehand, you'll be that much closer, to easily getting a quick spotless gun head interior...same technique works if you happen to get things setting up in the gun (some of the higher solids 2K primers may under the right / wrong circumstances).
In the past, I've always used lacquer thinner. Mainly, because as far as cost for a solvent goes, it's on the low spectrum. Evaporation rate is tame compared to other solvents, and it's an odor that is tolerable as well, probably a slightly lower flash point to.
That aside, in actual terms of "solvency", lacquer thinner is medium on the list. I've been playing w/ epoxy resins lately, shooting them, and the solvents that work to thin it, also happen to cut through the cleanup pretty easily. You figure if it breaks up resin that's starting to kick and has already begun gellation, it'll sure work dandy on less tough materials (unmixed components of epoxy resin can be roken down quite readily w/ orange goop or even white vinegar). But, xylene and MEK are great solvents (just have lots of downside in terms of odor, flammability, etc...bottom line, is avoid inhaling any solvents, even the "lesser" is still bad enough...I'm in the habit of donning a plain old charcoal respirator when I mix the paint or clean the gun).
Playing around w/ experiments causing resin kicking in the gun, it was nice to do this. It was at the point where the viscosity was too much to move things, so a quick percolation, and things were clean and flowing (I was pleasantly reassured at just how well a job it did, as there were no remnants of the epoxy in the internals...I know, cause I was using pigmented resin, and nary a reminder).
Perking is good in between base and clear but if you really want to clean the gun you need to expose the parts to brushing and rinsing. We use tools specifically designed for this purpose AND a squeeze bottle similar to a mustard bottle. We use about two or three ounces of thinner (at most) to clean a gun and that baby is really clean.
We've tested several bottles and found one that worked well with thinner for cleaning and with compound for buffing. We purchased a case of them so if you want one or two (they're pretty inexpensive) click on the link below.
04-07-2007, 09:54 AM
well, once again thank you for the discussion.. My gun is all nice and clean now. I had trouble getting the fluid tip out, it was in very tight, had to use super care not to let the wrench slip, I'm thinking the threads had some paint on them, acting like locktite. But, I'm good now...
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