Micro-Bubbles with an Air-Assisted Airless

Compared to a cup gun, an AAA spraygun might shear the fluid and introduce gas that creates tiny bubbles in the wet coat. Here are some suggested work-arounds. April 19, 2011

Question
I am having trouble with micro bubbles when applying agualente with a Kremlin AAA. I checked the Knowledge Base and found that adding denatured alcohol would solve the problem. I called my sales rep just to be sure that this would not void any warranties. He claimed that this would reduce the open time and not solve the problem. He suggested spraying lighter coats or using their flow enhancer. I switched to a cup gun using the same batch of lacquer and it laid out beautifully. My question is how do I get the same light coat with the Kremlin not having the same control that I have with the cup gun? What tip, air, and material setup are you waterborne guys using on the Kremlin? Any other tips involving technique to get a thin coat?

Forum Responses
(Finishing Forum)
From contributor J:
I have usually seen that problem associated with AAA sprayers. The solutions that I have seen have been to use a larger diameter pick up tube, a larger diameter fluid hose, a filter with larger mesh, etc. I know that Cat Technologies has an AAA that is designed specifically for WB and it has the above modifications.



From the original questioner:
I was afraid of that. I'm hoping to not have to buy a new setup.


From contributor J:
One thing I would try to do right away is to experiment with a few different tip sizes and change the filter in the gun to the next bigger size. That is a fairly inexpensive thing to start with. The next thing I would try is to hold the gun farther away from whatever you are spraying. If you are at 8" try 10-12 inches instead and see if that works. I know for me it has made a difference with some of the WB's I have used. Keep me posted on if any of that works. If not I can try some other pointers.


From contributor P:
Do a search on shearing here on WOODWEB. There is lots of discussion on this topic. I think I read that Kremlin had newer tips specifically for waterborne. Also, make sure your pump has no air leaks, and that it's primed thoroughly before putting the tip on the gun.


From contributor W:
The flow additives really do work with waterbased finishes. I have been spraying Aqualente with a Kremlin for about two months. I actually like it better than the other waterbased finishing I have used. I am using four ounces of XIM latex extender to one gallon of Aqualente. I buy the extender at Sherwin Williams. Iím sure the ML stuff is just as good or better.

I am using a 09-114 tip with fluid pressure set at 25 psi, with the atomizing air set between 20 and 25 psi. I keep these as low as possible, but still get a good pattern. It does go on with a bit of micro bubbles, but they are gone within 30 seconds.



From the original questioner:
Thanks everyone for the good advice. I will call my Kremlin distributor on Monday. I spoke with them when I switched to waterborne and they said I was using the best setup they offered but that was over a year ago.


From contributor U:
Be careful when stepping outside of a particular products family. Not all products are intermixable (SW with MLC) and you could have problems, if not immediately further down the road. Also, keep in mind if you have problems with the finish, where do you go? Sherwin will say it's the MLC and MLC will say the problem is the addition of someone else's product. That's a bummer. A larger tip would be most important for your gun. CATech might have a tip that you can swap out to "upfit" your Kremlin. Don't add alcohol because it will speed up the drying- not good. Flow enhancers/lighter coats will be best.


From contributor R:
My recommendation is to make sure your finish is not getting too cool and increasing your viscosity. You will want to spray it around 30 seconds in a Ford 4 visc cup at room temp. Add some distilled water to lower viscosity if needed. Also, typically a smaller tip and slightly higher air pressure helps atomize Agualente the best and helps to eliminate any trapped air from your AAA equipment.