Switching Airless Rig from Lacquer to Latex Paint

      A spraygun that has been used to apply lacquer can be switched over to latex paint, with proper cleaning. Here's how. October 15, 2010

Question
I build and finish custom furniture and have been spraying pre-cat lacquer and vinyl sealers through a Graco Airless sprayer for the past year. I have not been receiving the results I wanted, so I switched to a pressure pot system and I love it. My question (that no one in Utah can seem to answer) it this: since I have been using my airless system to spray lacquer, is it possible to clean it and then use the same pump and hoses to spray latex paint?

I've asked professional painters and received mixed answers. I've asked the people at Sherwin Williams and they can't answer me. I've asked other furniture builders and cabinet guys and they don't have a clue. Does anyone know the right answer to this question? I'd like to keep the airless and use it to spray latex in my new house, but I realize that may not be possible. Or is it?

Forum Responses
(Finishing Forum)
From contributor B:
That's pretty much what all painters use. When you do use it for interior walls make sure to back roll it as you go otherwise you'll be in a world a hurt for touch up and repainting.



From contributor W:
My advice would be to not run paint and lacquer through the same hose and gun. It takes a lot of cleaning (translate that to time) to be sure that all of the paint is out of the system. It only takes a very few specks of paint that didn't get flushed out of the system to ruin a furniture finishing job. For painting jobs, I used a separate, inexpensive gun along with another fluid hose. I assume that you are placing the container of material in the pressure pot, so it shouldn't be necessary to clean the pot between changeovers, and you can use the same set of pressure hoses.


From contributor J:
Which model Graco do you use? I use the Finishpro 395 for paints and clears with no problems. What do you not like about the finish quality?


From the original questioner:
To clarify, I will be using the pressure pot only for lacquer, and the airless only for latex. If I clean the lacquer out of the airless line, and only shoot latex paint through it, will that work? Do I clean the line out with lacquer thinner and then run water through the line? Or what is the proper protocol to flush the lacquer out so I can spray latex?

I have an old Graco Nova which is about 10 years old. It pumps fine, and I spray with a fine tip made to shoot lacquer, but for some reason I just canít get a super-smooth and even finish. I spray with the pressure almost all the way down, but still it seems like half of my material is wasted in over-spray, and I still end up with a crappy finish. My pressure pot system is still not as nice as an AAA, but I seem to get a better finish with the pot than with the airless.



From contributor B:
The pressure pot has less (far less) fluid pressure than an airless, so a lower coating velocity, and thus, less bounce back of the coating from your part. This really means you have less overspray bouncing off your parts and landing back on the surface after it's skinned over. However, your transfer efficiency has not increased even though it may appear that you don't have as much overspray.


From contributor G:
Yes, it's fine to switch a gun over. Run thinner through the gun, then acetone, after that pull the cartridge filter and clean it out, then run denatured alcohol and finally clean warm water. If you are planning on keeping this machine around awhile it may be worth the investment of getting a new hose and filter for it. Also make sure you get the right tips for running latex.


From contributor I:
The answer is yes. You can use your airless to spray latex paint. You may need to thin it until get the right viscosity according to your airless gun, or you can change the size of your airless gun tip to get the better result. Don't forget to always clean up your equipment after you finish your job. Latex paint when it is dry is hard and very difficult to be clean up.


From contributor U:
I agree with the other posters about it being doable to switch an airless over, or even the pressure pot system. Whether you are doing it once or for good, you have to decide if it is worth the time or possible aggravation. As a rule yes, but when switching from a clear finish to paints, as mentioned, you sometimes for a while, stand the risk of getting a few flecks of the old finish into your spray. I prefer never to do it for a short or small job, but have done it quite often for larger projects. Time you consider the time and cleaning materials required, an extra spray system looks better and better.


From contributor Y:
I have a Spraytech 2305. I run whatever pleases me. I just, as was repeatedly suggested out, clean up after myself. If you've been running lacquer, dump a half gallon of lacquer thinner in a one gallon bucket and drop your pick-up in. A bit of acetone wouldn't hurt for the actual clean up. Pump out of the bucket, with the hose feeding right back in. When you think you've flushed it good, switch to a fresh batch of lacquer thinner (no acetone). If it runs reasonably clear, you're ready to fly for your latex runs. You can save the dirty lacquer thinner for future initial cleans (the sediments will settle and can be tossed).

When done shooting latex, flush, then flush some more (about seven to ten gallons of water). Then fill the hose and pump with mineral spirits, or a non-hardening oil with a little thinner. I like to add a little alcohol too, since it mixes with water and oil. Also, I might throw in a couple teaspoons of lacquer thinner, since it dissolves oil and latex. Water in a pump, even a stainless one, will corrode it. If you go back to lacquer in the future, you may want to flush with lacquer thinner again, as described above. Obviously, a clear lacquer finish isn't going be as tolerant as a latex paint job on a house or cabinet.



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