b'ARCHITECTURAL SHEET METALTHREE-COAT VS. TWO-COAT PAINT SYSTEMS FOR BUILDINGSBy: Kathi MillerArchitectural National Accounts, McElroy MetalMore is better right?For many architectsclearcoat is necessary to improve the color retention and and building owners, the decision of three- chalk resistance of the solid color or metalescent base color.coat vs. two-coat paint systems certainlySaturated colors like reds, oranges, and purples are good isnt black and white.examples of colors that may benefit from the addition of a Whats the Difference?clear coat. A clear coat may also be needed for some metallic As the name implies, one system has three layers of coatingcolors, like bright silvers, to protect the aluminum flake from (or film), and the other consists of two coating layers. Mostlosing its brightness and turning dark. Lastly, there are some often, a two-coat system includes the primer and a top coatspecial effect coatings available on the market that may also whereas three-coat systems include the primer, top coat,require three-coats; a primer, a base color coat, and an effect and a third coating (most often a clear coat) that is appliedcoating. over the top. Outside of these situations (saturated colors like reds, oranges, So, while the apparent difference involves the number ofand purple; bright silvers and special effect coatings), three-coating layers, there are other important differences. Whencoat systems are rarely necessary nor beneficial.the coatings are applied, two-coat systems can be producedLead Times & Minimumsin one pass through commercial coil coating lines, whereasAs mentioned earlier, most manufacturers consider three-three-coat systems routinely require a second pass throughcoat systems a special order.Consequently, they involve the coating lines. longer lead times and minimum quantities. For large projects, Additionally, two-coat systems tend to be industry standard forminimum quantities are often considered a non-issue. However, most manufacturers, while three-coat systems are most ofteneven if the original order easily meets the guidelines, its considered a special order. As you might guess, these lastimportant to remember that replacement panels or small two nuances can carry both cost and lead-time implications. amounts needed for building additions or modifications at Are Three-Coat Systems Necessary?later dates can be problematic.For the vast majority of colors, a two-coat PVDF system of aMaterial Costprimer and a topcoat are sufficient. There are, however, timesMaterial cost is a consideration in almost all projects. Two-coat when a three-coat PVDF systemprimer, color coat andsystems can be applied in one pass during the coil coating 10 www.mrca.orgMidwest Roofer'