Using acrylic latex paint for sign finishes

By Gary Anderson

Posted on Friday, December 3rd, 2021

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One of the biggest changes in our shop in the last ten years is the exclusive use of water-based acrylic house paint for graphics and finishes. These paints dry slower than some of the other water-based paints designed for sign work, and in the brush, they resemble the feel of enamel.

We had been using acrylic for twenty years on our dimensional signs, but our overlaid plywood signs were done with enamel. The question was: Could we use the same techniques with acrylics on flat painted signs that we were using with enamel? With some experimentation and working with a brush manufacturer to create brushes designed for this paint, the move to water-based paints was painless. Since we only did dimensional and flat signs, we could now do everything with acrylics.

The main reason we switched to acrylics was to produce a longer-lived sign, but we found many other virtues. There are no fumes, we save money and we thin only with water. We were able to use roller covers almost indefinitely by slipping them into a plastic bag after each use. There are no skins in the paint cans, and you can clean your hands or clothes with soap and water. We can produce work faster, yet create a longer lasting product. This is a rare combination—not to mention that water-based paint is a more environmentally friendly medium.

Think about it. House paint is designed to be used mostly by homeowners and protect something much longer-lived than signs. Availability of rich colors used to be a problem with acrylics, but isn’t any longer. The task is to find a good quality house paint that offers good coverage.

Environmental regulations have had a huge impact on the quality and longevity of paint, especially enamel. Nearly all of the most durable pigments have been banned, and that affects all types of paint.

Don’t expect your colors to last as long outdoors as they used to, no matter what kind of paint you use. We are applying more and more water-based UV clear overcoats from Ronan Paint Co., Triangle Coatings and ClearStar to keep primary and pastel colors from fading prematurely. One of the major things we were able to achieve by using these products was the elimination of oxidation.

Working with acrylics Here are a few tips for working with water-based acrylics:

■ When rolling a flat panel, use a 3⁄8-in. nap roller with a PVC core. Store it in a plastic bag for reuse. The finish will actually get smoother as the roller mats down.

■ Don’t overwork the paint or pour on too much paint. Thinning with a small amount of water added is helpful. You will never be able to achieve that high-gloss wet look with acrylic, but I like the softer look better. It also sprays well.

■ On overlaid plywood or any natural wood, round the edges of the material slightly. This lets the paint film flow evenly over the edge. All paint tends to pull away slightly from a sharp edge—leaving you with the least protection where you need it the most.

■ Start with a water-based primer on wood or plywood. When the primer is dry, sand and add a second coat of primer if needed. Follow with two finish coats, sanding between coats.

■ Acrylics are also great for coating pressure-treated lumber. This wood has a high moisture content, and acrylic allows that moisture to pass through the film without removing the paint. If the finish gets nicked, it will not start peeling at that spot.

■ On high-density urethane board, it is not necessary to use primer unless you are using a high-build primer to fill pores. Acrylics are good at filling the pores, but four coats of paint are recommended for a good finish—especially for gilding.

■ Due to recent formula changes in certain gold sizes, I recommend that you apply a barrier coat of an acrylic primer/sealer before applying gold size over acrylic latex paint to avoid failure. I use Chromatic Paint’s TiCote for this.

■ Wait 48 hours before gilding over acrylic paints. This will ensure that gold will not stick to the background. Once the background is thoroughly dry, gold leaf will not normally stick to it. If a stray piece sticks on a humid day, it can usually be removed with a wet cloth.

■ Lettering with acrylics is about the same as working with enamel. You can pre-thin in the can or dip into water and palette. The water-based brushes should be well cleaned and laid out to dry for reuse. Enamel white bristle fitches can be used with water-based paint for pictorials or to paint textured backgrounds on sandblasted signs.

■ Friskets or masks can be used, but once the frisket is applied, a thin coat of the background paint needs to be applied over the frisket and allowed to dry. This will seal the edge and prevent the lettering color from bleeding out under the mask. I use Gerber ScotchCal 220 film.

■ Vinyl application is the same on an acrylic finish as on an enamel one, with a few minor exceptions. Since acrylics come in three finishes—flat, satin or gloss—use satin or gloss acrylic for the background when you’ll be applying vinyl graphics to it. If you have a problem with the application tape lifting the graphics off when you remove it, leave the vinyl on the panel with the application tape on it for a minute or two before removing the tape.

■ One nice thing about acrylic is the removal of vinyl if you have to take it off later. With a little heat, it comes off much easier and cleaner than when on enamel.

■ Glazing is a nice effect and it is easy to do with acrylic. Use a glazing medium mixed with regular acrylic latex house paint to the intensity that you need. Be aware that glazes are weak and will not last as long as full-strength paint.

 

Gary Anderson’s shop, Bloomington Design, is in Bloomington, Indiana.

 

Gary Anderson’s shop, Bloomington Design, is in Bloomington, Indiana. Now retired, he has contributed to SignCraft for over 35 years, and authored two books: Signs, Graphics & Other Neat Stuff and More Signs, Graphics & Other Neat Stuff, both published by SignCraft.