Cleaning Airless Spray-Gun Tips
From Paul Snyder, forum technical advisor:
I have an assortment of those needles for the fluid tip and they do work when needed (I need a magnifying glass). A lot of times, I can clear the tip by spraying lacquer thinner back into the bucket. It takes a minute or two sometimes, but almost always works. I turn the air down and the fluid up when spraying the lacquer thinner back into the bucket. Check your fluid filter, also. Usually, if I get a clog in the tip, the filter needs cleaning as well.
Get some spray gun cleaner and soak them for an hour or two. This will dissolve the junk that collects in the tips. Put the air cap in, as well. I have the cleaning needles and they will only do so much.
In my opinion, lacquer thinner can almost contain any variety of solvent. Get a closed can with a tight lid and soak them in acetone, which I pick up from the local Sherwin Williams store. That should do the trick. Also, a cheap alternative is to buy some sewing machine needles - they have a bigger end to hold onto.
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Comment from contributor G:
If material is building up on equipment through long periods of use, take a break to brush the gun, etc. down with appropriate solvent. Breaktime, lunchtime may require soaking gun in container of solvent (may not be the best practice in the case of really hot solvents) or even cleaning the entire system (lines, (airless) pump and gun) depending on material being sprayed (most particularly fast-setting epoxy, etc). Some hardening finishes may require periodic cleaning due to "boundary layer hardening". Essentially, the fluid in the lines etc. that is immediately adjacent to the line does not move. The material flow is through the center. The boundary layer is incredibly thin but will eventually harden in the case of fast-setting type materials and the hardened layer will get thicker over time. Not a problem for most materials in that once or twice daily cleanup will remove the very slow build-up.
As regards cleaning spray equipment in general, salvage any un-sprayed material as best possible (short of running an airless sytem dry). Set up a small container of solvent that will be wasted. The amount should be at least equal to the capacity of the system. For example, in an airless system, you would need enough of this waste thinner to fill lines, gun and a little extra for the initial flushing of finish. Start running that waste thinner through, directing output to another container to collect any nearly pure finish that is being pushed out and the initial bit of very dirty thinner. After the initial bit has run through, let the output be recycled through the system to thoroughly clean the lines, gun, etc. Loosen nozzle and other fittings a bit to blast clean the threads. In the case of airless, this past step would be done without the tip, but you would now replace the tip, reverse it, and blast it, too. For airless, all of the line cleaning, blasting, etc. can be done with the gun underwater in the solvent using pressure and trigger control to avoid making a big mess.
Then repeat the above process using another batch of clean thinner. When you're done, the clean thinner will not be totally clean, but it will be just what you need for the next session's dirty thinner, first wash. Even with 100' of airless line, you can get waste thinner per session down to about one quart. After flushing the equipment, a little brushing and wiping with clean thinner should finish the job. Now's the time to make sure parts are moving properly, etc. and consider wiping down with oily rag. Proper cleaning of the equipment should be part of the process in the case of professionals, and will eliminate your problem in the future.
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