Keeping AAA Tips Spraying when Using Waterborne Finishes

Tips on keeping your tip clean (waterbornes will skin over with even a short pause in the action). April 19, 2011

I'm having a heck of a time keeping my AAA (CAT) tips spraying properly. I've tried every way I can think of between sprays to keep the tip clean but none seems to work consistently. Brushing off the tip with water and leaving it seems as effective as any but I still have problems with inconsistent spray patterns and can often be frustrated cleaning and cleaning again to get it right. Any suggestions?

Forum Responses
(Finishing Forum)
From contributor B:
I store my tips and caps in a small glass jar filled with Denatured Alcohol. I just toss them in the jar if I'm taking lunch, shutting down for the day, or for extended periods of time. They are permanently stored in the jars. If I need a quick clean up during spraying session, I'll use water and a tooth brush, unless they are really bad, then I turn to the DNA. I have no problems with clogging or uneven spray patterns.

From contributor F:
Water based build up on spray tips is a pain with any spray system. I gave up on using AAA for water based finishes because of this (and micro bubble issues that I could not resolve.) Now I use a Graco Triton diaphragm pump with an HVLP gun for all water based finishes and leave the AAA for solvent based only. Problem solved for the most part.

From contributor B:
I have the CAT H20 AAA and Bobcat gun with the newer opti tip installed which is specifically designed for waterborne materials. You may want to give their new tip a try. I've had little to no problems with build up or micro bubbles.

From contributor E:
I have a plastic 2 liter can that is half filled with solvent gun wash and keep the gun head cap down in that. It sounds incompatible but I just shake off the gin and keep a rag handy to wipe drops before spraying. It works just fine. Keep a small linear brush to scrub the tip from time to time. This is with waterborne.

From contributor J:
I am spraying with the same outfit as you including the new tips. The problem seems to come from finish that starts to dry in the area between the end of the needle and the tip of the tip. I have thought of Contributor Dís solution but not tried it yet. I think I will and see if that helps.

From contributor A:
We also had problems with tips clogging. It was back when we sprayed at a lower fluid pressure, like around 350 to 400 pounds. Now we spray at 500 to 550 and we don't have the problems near as much. Seems the lower pressures couldn't clean off the drip that forms between some of the longer spray intervals.

From contributor H:
Are you sure that your needle seat isn't leaking? Once you release the trigger, no more material should be weeping out the tip.

From contributor P:
I have that setup, too, and see the same problem sometimes. Certain products/tip combos seem to be worse than others (Agualente + .09 tip, for example). You just have to stay on top of it. I use a really stiff brush plus water (looks like a toothbrush but stiffer). I also submerge the gun head in a bucket of water. If you pull the trigger part way (or pull the little pin behind the trigger), it activates air only and will blow the excess water out of the head. I jack up the fluid pressure. Atomizes better, gets rid of the tails, and clogs less.

From contributor O:
I get the same thing through my CAT AAA with the bobcat gun and previously I had an Asturo K20 pump with both the Asturo and the bobcat guns and they all did it. There is just a drop of fluid that gets past the needle and it dries in the tip after ten or so minutes and requires cleaning.

I talked to the tech at CAT and was told to make sure the white plastic washer behind the tip is in good working condition and to seat it by tightening it without the cap first. That didn't work for me at all so i just keep a tip cleaner handy.

On a side note - for those of you that are using WB finishes, the best cleaning setup I have found is to get one of the 40 gallon parts washers they sell at Harbor Freight, Grizzly etc and then fill it with a 10/1 solution of Simple Green. You can use this to wash out all of your spray guns (I have a bunch running PPS cups that I use for paints, primer, spray stains, glazes, etc.) and I just dump the gun in that overnight and in the morning scrub it a bit with a toothbrush and it is good as new. I also soak the AAA tips in a cup of simple green that I leave on the tray in there and they are ready to go in the morning. I also soak the AAA pump parts in it on occasion as well as the pickup tube and the hoses if they start to get buildup on them. Rinse with clean water when done and they are good to go. Simple green is the best/most cost effective cleaner that I have ever run into for WB equipment.

From contributor R:
I have sold 1,000's of AA guns for water based coatings. The big problem is people take the air caps over and then just let them soak in solvent or water. The coating is in the tip itself. It needs to be blown out of tip with water. At the end of the day, flush the pump and gun, which includes the tips, and then wash them off.

I do not sell ultra sonic cleaners, but a small clean filled with Jam Stripe will completely clean the tips if you do not want to flush them with water. You have to clean the inside of the tip to keep it clean. A second solution is to use a Microfilter instead of the standard tip o ring. But you still have to keep the inside of the tips from drying out.

From contributor Y:
The big problem isn't what happens at the end of the day but what happens in the 5-10 minutes or half hour between spraying when the finish hardens on the end of the tip causing you to clean it before resuming IME.