Advice on Spraying Latex Paint

Success with latex acrylic paints requires an appropriate spraygun setup and a lot of fiddling with the variables. July 11, 2013

Question
I spray a lot of lacquer, but every once in a while I have a customer that wants latex (to match existing). Can anyone tell me the best system to spray latex that won't kill me budget wise? I have a problem when I try to spray it through my gravity fed gun (too thick). Or is it possible to get the lacquer matched exactly?

Forum Responses
(Finishing Forum)
From contributor F:
I stay away from latex but if you have to use it, try a larger tip, and thin the latex. Air assist airless can be bought for a few hundred, but I'm not a fan of that either. Educating the customer seems to work well for me. You can provide a far more professional looking finish that will provide superior chemical, moisture and scratch resistance than latex.

As far as matching, if you have a stickler for a customer, I think it is wise to educate them about the differences in the coatings. A solvent based coating will amber at a different rate than a latex. So if it matches perfect today, it probably won't a few weeks from now. Letting them know that will keep you from having to do a refinish down the road. The accuracy of the match will depend on the talent of the tint specialist at your supplier. If you use a product like Stealth from MLC, it will not amber with age, so if there is ever a shift in color, you can tell the customer that it was the existing coating that shifted in color, therefore keeping you from eating a refinish job.

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From contributor D:
Spraying latex is truly an issue of viscosity, pressure and atomization. Working with either a cup gun or gravity gun will most likely give poor results, since the latex viscosity is too thick to pass through the gun with either suction or gravity... Air assisted pot systems seem to work better because you can directly increase the pressure at the pot to push the paint through the gun. You will need to play around with the settings to get things adjusted properly. You may need to also play around with thinning the paint. I often add a lubricant, such as Floetrol, to the paint to allow it to pass through the gun easier.

You will need to play around with everything; thinning paint, adding Floetrol, adjusting needle and cap sizes, pressure at pot and gun settings, in order to spray latex properly. Even then it will not look like lacquer, period. I have been spraying latex, as well as solvent based finishes, for many years and can get some very good results, but it is a difficult medium to achieve good results with.

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From contributor L:
Use a pressure pot or a pressure cup gun. Home Depot sells a cheap one for about $70 that works well for latex. They never seem to last that long, about 1-2 years with good maintenance. But they spray latex nice with only a slight thinning.

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From Paul Snyder, forum technical advisor:
With practice, you can get decent results with latex paint. Make sure it's 100% acrylic and thin it 20% - 25% with water. The surface won't be really smooth like a furniture finish, but it looks good on built-in cabinetry and millwork.

If your compressor supplies enough air, the Binks Mach 1 HVLP spray gun with a 1.5mm needle and 92 air cap does a good job.

In my area I have 4 major coatings suppliers - Becker Acroma, Chemcraft, ML Campbell, and Sherwin Williams (along with a supplier that has Matthews catalyzed poly). These suppliers can match any paint color using NC lacquer, acrylic lacquer, pre-catalyzed lacquer, post-catalyzed lacquer, conversion varnish, and catalyzed polyurethane. If you want to stick with finishes that you're used to using, you should be able to get them mixed to any color you want; just choose the one that offers the durability you need.