Extending Wet Time with Pigmented Varnish
Using an airless air-assisted gun and a pigmented varnish, a finisher has trouble keeping the large cabinets wet to avoid overspray problems. Here, he gets advice about formulas and tip sizes that may solve his problem. December 15, 2005
Question
I somewhat recently bought two Kremlin 20-25 pumps with the new MVX guns. I am in the process of getting used to air-assisted airless spraying because I have been used to spraying with pressure pots through the years.
I have just started using M.L. Campbell's resistant pigmented varnish and am having some problems getting the finish to do right each time. I build and finish big cabinets sometimes (with the backs attached before finishing) and I have to keep the finish wet for a decent amount of time so that I won't have overspray problems. My M.L. Campbell rep told me to add a maximum of 20% flow enhancer #2 to the resistant to slow the drying time and to allow the solvent to escape and to avoid solvent pop. I have done this (adding 20% flow enhancer #2) and I still have problems sometimes with the finish drying too fast and with solvent pop. My M.L. Campbell rep has heard that other finishers were having problems with the MVX spraying the resistant pigmented varnish. So, my rep thinks my gun is the problem.
Do any of you have knowledge of this? I have tried adjusting my fluid and air pressure to different settings according to what my gun salesman and my M.L. Campbell rep have told me. Sometimes the finish lays out nice, but I want it nice all the time. I just need to know what to do, whether it's an additive in the paint or a pump and gun setting, to make it right. I didn't check my viscosity yet, but it was app. 85-90 degrees when I sprayed it with 20% flow enhancer #2 added. Any suggestions would be greatly appreciated. Thanks in advance.
P.S. I was spraying inside my paint booth with the exhaust fan and the air make-up unit running.
Forum Responses
(Finishing Forum)
From contributor M:
Did you try the formula that I gave you when you first asked this question? If not, you should really try it because we use the same equip, the same finish, have experienced the problem and this is what makes everything work out perfect. Where are you located? Different locations will have different climates and therefore cause different needs. We are in the northeast and have found this mixture to work in all situations.
From contributor G:
When we first started with Kremlin, we did the same exact thing - play with knobs to see if it corrected the problem (way you run conv. or HVLP technology). We were wrong - all we had to do with Kremlin was go down a tip size. If you are running 09 tip, go to 06 or 04, Kremlin rep will know what you are talking about. Extremely simple once you get the hang of it, and keeps the production more idiot proof from the Tim Taylors of the world.
From the original questioner:
I appreciate the advice. I am located in Georgia. I asked my ML Campbell rep about the reducer, but he thought that I should just stick to the flow enhancer #2. I just want whatever works. I do spray big cabinets with the backs already attached. Sometimes the base cabinets are eight or nine feet long. So, I need to keep the finish wet long enough so that I can spray everything without overspray problems. If I use the reducer in place of some of the flow enhancer #2, will the finish be kept wet long enough for me to spray the big cabinets with the backs already attached? I'm just not familiar with the reducer. I'm also going to look at getting a different sized tip.
From contributor M:
The reducer allows the finish to stay wet longer. From our experience the flow enhancer really doesn't make a whole lot of difference. I can't understand why your MLC rep would not tell you to use the reducer. It is pretty much standard issue here.
I strongly suggest that you try the mixture that I've posted. Also be careful with the amount of reducer you use, if you play around with the amounts. Too much reducer will change the sheen.
From the original questioner:
I appreciate the information. The tip size that I am using is an 09-094 size tip. I think that is a 13,000's size tip. This is actually the tip that came with the gun when I bought the gun last year. I agree with you about the drying time when using the flow enhancer #2 only. I don't think that it is keeping the insides of the big cabinets wet long enough for me to be able to spray everything without having overspray problems. I am going to try the reducer, like you said. And possibly going to the next size larger tip. At least this is what my Kremlin gun rep suggested. But, I will try the reducer first. Just out of curiosity, what are the biggest items that you spray while using the reducer and are still able to keep the finish wet long enough?
From contributor M:
I hope it works well for you. We spray mostly kitchen cabinetry except for the occasional commercial piece. We can spray a large refrigerator cabinet this way. We've also sprayed very large furniture style islands. Everything is face frame with backs off. This becomes very difficult the larger the pieces become, especially when you add furniture toes, panelized ends, brackets, etc. Sometimes we just end up having to tape things off.
