In Part One, we discussed The Hidden Strength of prepainted metal. It’s easy to take for granted all that lies beneath the surface of prepainted metal: the cleaning and pretreatment of the base metal, the metallic coating, and the continuous process that prepares the metal strip for primer and topcoat, all in one pass through the coil coating line. Here in Part Two, we’ll learn about the only feature that is actually visible in a prepainted part—the topcoat; that is, The Visible Beauty. There is, however, more to it than meets the eye.
The Visible Beauty
Look at a prepainted article and you see color, shininess (or glossiness), perhaps a printed pattern, or maybe a texture to the surface of the topcoat. Color is the most obvious feature, so let’s discuss that first.
To produce a colored coating, various colored pigments are blended together. One requirement for a coil-coating topcoat is heat resistance, so the pigments used must be able to “take the heat.” All coil coatings are baked at relatively high temperatures, certainly much higher than those of other industrial coatings. Since much of the prepainted metal produced is used in the metal building products industry, and since the expected lifetime of prepainted metal is very long in this application (at least 20 years, and 40+ years is not uncommon), the pigments selected must also provide exceptional weathering performance properties. Fortunately, the formulators of coil-coating topcoats have a variety of pigments from which to choose. Most of these are super-durable inorganic pigments, but there are also a few high-performance organic pigments that are used when deep, dark, saturated colors are desired. Prepainted metal is offered in an extensive range of colors.
You may have heard the term “solid color.” This simply means that the color is uniform across the surface. Prepainted metal is mostly produced with a solid-color palette. This is not to imply there is a limitation associated with prepainted metal, but rather demonstrates what consumers prefer. But prepainted metal is certainly not limited to solid colors. Colors with a metallic shimmer are also available to offer some more interesting aesthetics. Metallic effects may be introduced into a coating by adding either metal flake pigments to add sparkle or pearlescent pigments to produce a metallic luster look. Nearly all automotive finishes utilize a metallic effect, and coil-coated metal building products can do the same. Of course, this stunning effect must be coupled with long-term durability, and prepainted metal offers both—beauty and durability.
In addition to the sparkle and luster metallic looks, some pigments can create a color-shifting effect. Talk about adding interest value! Although such an effect may not be for everyone—or for every prepainted article—the capability is there. If you want it, we’ve got it!
The way light reflects off the surface of an object is an indication of its gloss level. Consumers prefer high-gloss appliances, but most building products (wood, shingles, etc.) have a substantially lower gloss than appliances, and therefore the gloss of coil coatings used for prepainted building products is also much lower. In many cases, the metal itself has a tight pattern pressed into it to lower the reflectance while also adding an interesting aesthetic effect.
As mentioned above, the metal may have a stamped-in pattern, but it is also possible to create a texture within the coating itself. In the distant past, formulators used hammertone and “wet look” wrinkle finishes for industrial coatings to create an interesting look, for example, on a toolbox or bicycle frame. More often than not, however, the texture most interesting to a consumer of prepainted metal is one that creates a more subtle look and feel.
Clever formulators continue to create new looks to add distinction to prepainted metal. So far, we have just scratched the surface of what is possible. But color and texture are only The Visible Beauty of prepainted metal. In Part Three, we’ll discuss The Functional Capability that is the objective of our hardworking coil-coated products.
David A. Cocuzzi
NCCA Technical Director