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By James Piper
August 2006 -
Maintenance & Operations Article Use Policy
When it comes to selecting a paint, facility executives are faced with a variety of options. Both a blessing and a curse, the large number of choices enables facility executives to closely match the characteristics of the paint to the requirements of the application. But unless one understands paint characteristics, it is easy to select the wrong type of paint for the application.
Compounding the problem is the wide range of paint prices. The lowest cost paint may not be a bargain, particularly if its service life is half that of a higher quality, more expensive paint. But always selecting the highest cost paint also may not be the best option. Facility executives may be paying for paint characteristics that are not needed for a given application.
When evaluating paint options, it is important to remember that paint cost increases with increasing paint quality. This is primarily the result of two factors. Quality paints tend to use higher cost components than paints of lesser quality. Higher cost components translate to higher product costs. Quality paints also have a higher concentration of solids. As a result, higher quality paints have a long list of advantages: They are are easier to apply, flow better during application, require fewer coats for the same coverage, splatter less during application, have better hiding characteristics, hold color better, resist pealing and flaking, resist mildew, and provide a longer service life.
While these characteristics are common to all high quality paints, the problem is determining just what a quality paint is. It isn’t good enough to simply rely on the name of the manufacturer; most manufacturers offer a range of paint qualities. Instead, facility executives must look at the components that go into a paint, particularly their quality and concentrations. This is the only way to determine the difference between a top quality paint and one of lesser quality.
Paint has four basic components: pigments, binders, liquids, and additives.
Pigments provide the color (or whiteness) to the finished product. They can be organic or inorganic. Their concentration has a direct impact on the durability of the paint’s film.
One measure used in evaluating the quality of a paint is the pigment volume concentrate, the ratio of the pigment volume to the total volume of solids in the paint. Expressed as a percentage value, the pigment volume concentrate indicates how much binder is contained in the paint to surround and protect the pigment. A pigment volume concentrate value of 45 percent is considered to be the optimum level for most applications. Paints with lower pigment volume concentrate values produce a high gloss finish, poorer color uniformity, lower tensile strength and lower permeability to water. Higher pigment volume concentrate values tend to increase water permeability and the risk of blistering and rusting.
A paint’s pigment volume concentrate also helps determine the sheen level. As more pigment is added to the paint, the pigment volume concentrate value falls and the finish gloss of the paint decreases. Manufacturers can also reduce the finish gloss by introducing larger pigment particles. In general, low pigment volume concentrate paints adhere better and last longer. The glossier the finish, the more durable it is and the easier it is to clean.
Paint binders are used to help bind the paint pigment to the surface and to bind the pigment into a continuous film. The type, quality and quantity of binder used in a particular paint will affect a wide range of performance characteristics, including durability, stain resistance, adhesion and crack resistance. In most cases, the higher the quality of the paint, the higher the paint’s ratio of binder to pigment.
Manufacturers use many types of binders, depending on where and how the paint is to be applied. Different binders can be used to improve the paint’s resistance to moisture permeability, sunlight exposure, damage from abrasion, adhesion to the surface and flexibility.
Special applications, however, will require working with the manufacturer to determine which paint binder is best suited to the application.
Another basic component of paint is the liquids. Liquids carry the pigment and the binders. In most paints, the pigment and binder solids account for between 25 and 50 percent of the total volume of the paint. The majority of the remainder of the paint’s volume is the liquid carrier.
Two types of liquids are used in paint, solvents and diluents. The purpose of the solvent is to dissolve the binder and hold it in suspension along with the paint’s pigment. In oil-based and alkyd paint, the liquid is an organic material such as paint thinner. In latex paint, it is water.
In contrast to solvents, diluents do not dissolve the binder. While they help to keep the pigments and binders in suspension, their primary function is to reduce the cost of the paint. Higher quality paints have lower levels of diluents.
The fourth paint ingredient includes materials added to help produce certain properties of the finished product. Thickeners and modifiers make the paint easier to apply. Defoamers reduce the formation of bubbles during manufacturing. Co-solvents can be added to increase the hardness of the film formed by the binder. Other additives increase the splatter resistance of the paint during application. Biocides are often used in exterior paints and paints applied in high moisture interior applications to prevent the growth of mildew on the paint’s surface.
The first source for information in evaluating paint quality is the manufacturer. Manufacturers should provide information on paint ingredients, including the types of pigments and binders used, as well as the percentage of solids contained in the paint. Another good source for information is the material safety data sheet (MSDS). The MSDS will list several characteristics that reflect the quality of the paint, including the weight per gallon, the specific gravity, the flash point and the quantity of solids in the paint by both percent volume and percent weight.
Given the differences among paint formulas, ingredients, and performance characteristics, how does a facility executive select a quality product? While there have been attempts to set standards for paint manufacture and performance, there are simply too many variations between products to be certain that a fair comparison is being made. Add in the fact that different applications require different paint characteristics, and it is easy to see why there is so much confusion when it comes to selecting a quality paint.
One indicator of quality is past performance. Learning from the successes and failures of others is a painless experience that requires only a small investment in time. Talk to others who have similar applications. What paint has performed well in those applications? What paint hasn’t? As long as the two applications are similar with comparable requirements for paint protection and performance, the experiences of others can teach valuable lessons.
One caution: As they say in the investment business, past results are not a guarantee of future performance. Seemingly subtle differences in applications can result in major differences in paint performance. And manufacturers are constantly modifying their formulas, both to improve performance and to control costs. Either of these factors may be sufficient to make a particular paint unsuitable for an application.
Beyond experience, there are several rules of thumb to help ensure the selection of a quality paint.
James Piper, PhD, PE, is a writer and consultant who has more than 25 years of experience in facilities management. He is a contributing editor for Building Operating Management.