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Printing on Specialty Substrates

(April 2010) posted on Tue Mar 23, 2010

Managing variables associated with the substrates you use is critical to quality. Find out how to work with some popular, but picky, materials.

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By Gail Flower, Johnny Shell

Particle board is seldom printed as a decorative piece unless it’s covered with a veneer. Veneers are typically roller coated and cured with a UV clear coat. Enamel ink is most often used for decorative printing on veneers. The end result is only as good as the compatibility between the ink and the wood sealer; therefore, test before you print.

Drying ink on a wood surface is especially troublesome when using a heated conveyor dryer, because the wood fibers dry and contract too rapidly, which results in cracks. Air drying is safer, because solvent inks dry quickly while the wood releases its moisture naturally over an extended period of time. You must also consider grain direction when printing onto wood. A lightly sanded and sealed wood surface shows a very definite grain pattern after printing. You can virtually eliminate this pattern by thoroughly sealing the wood.

Several ink formulations are available for decorating glass. Ceramic inks contain finely powdered glass or frit and inorganic pigments and are fired at a temperature exceeding 1112°F. Enamel inks have oil-based media that disperse the inorganic pigments, glass frit, and additives and can be printed through steel, polyester, or nylon mesh. Oils burn off before the pigments, and the frit fire into the glass or ceramic. The whole cycle takes 1-1.5 hours, during which the temperature rises to 1112-1202°F for 10 minutes before the glass is allowed cool. The disadvantage of this method is that multicolor printing is unrealistic. Previously printed colors can be lifted off by subsequent screens.

The same is true for two-part epoxy inks designed for printing on glass. But, for single-color applications, ceramic inks are favored by beverage and cosmetics companies because of the visual impact of screen-printed images and presence of ink thickness.
Screen printing with ceramic inks and firing those enamels into the glass in a lehr can produce lasting, quality images; however, the process is slow and expensive for decorating beverage or cosmetics glass containers. A lehr uses substantial energy, and the temperature variations within it can cause color variations. The ink system also imposes design restrictions, because the resolution of printed images is limited by the minimum mesh size required by ceramic enamels.


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