Every paint has three components: a binder a solvent and a pigment. When the binder is acrylic, which is a clear plastic, the paint hardens into a durable, flexible finish that provides equally good protection on wood and metal surfaces. The method of applying acrylic enamel, which is essentially acrylic paint with a gloss additive, depends on the solvent. You can brush water-based latex acrylic enamel, but you must spray other types.
Acrylic Enamel Reducers
The solvent in sprayable acrylic enamel is a volatile, hydrocarbon-based solution that includes chemicals such as toluol and acetone. The specific mixture of chemicals in the solvent, also called the reducer, determines the ease of flow from the paint sprayer, the drying rate and the quality of the finished surface. Spray cans suitable for small jobs come pre-mixed, but when you apply acrylic enamel with spray equipment, you should always thin it with the reducer recommended by the manufacturer. The wrong reducer can lead to defects such as dripping, separating and a bumpy texture known as eggshell.
Unless you are spraying acrylic enamel from a can, you will need an air spray gun and a compressor to apply it -- it is not a job for an airless sprayer. While you will get acceptable results with a siphon feed spray gun, you will get better results by using a high-volume, low-pressure gun, which sprays paint at the same rate but with much less overspray. Besides polluting the air with toxic fumes, overspray can collect on the surface of the wet paint, creating a grainy texture when the paint dries.
The basic technique for spraying acrylic enamel is the same whether you use a can or a spray gun. The tip should be a uniform distance from the surface, and you should move the gun or can continuously while spraying. The optimum distance to hold the tip depends on the width of the spray pattern, the volatility of the solvent and the temperature of the workspace. When you find this distance, which is usually between 6 and 10 inches, you will leave a wet coat after each pass that levels out to a glossy finish without running or dripping.
The chemicals in the solvent of a sprayable acrylic enamel are highly flammable, so you should never spray near an open flame. They are also toxic and using them requires a respirator. If you spray outdoors, the surface you are painting should never be in the path of direct sunlight, or the paint will dry too quickly and crack. Moreover, moisture will interfere with the adhesion of acrylic enamel, so the surface you are painting must be dry. Avoid painting outdoors on humid days or on days when rain is likely.
Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.