Materials designed for high elongation can pull you in the wrong direction if you don
By Rick Davis
Garment screen printers face plenty of challenges. One of the greatest is the vast number of different substrates upon which they must print. Among them are high-elongation fabrics, which are some of the most difficult to work with. This month’s discussion will focus on printing on what is referred to generically as spandex or elastane, commonly known by the brand names Lycra, Elaspan, Linel, Dorlastan, Roica, and others.
The toughest part of decorating fabrics of this type is not so much the act of getting the ink onto the material, but getting the right ink onto the fabric and having it perform to customers’ satisfaction. A common mistake, one that many printers make when printing on fabrics of this type, is assuming that a common plastisol will do the job. The problem comes into play when the customer either puts on the piece of clothing or washes it for the first time. If standard plastisols were used, the result likely will be a print that will either crack once stretched and/or crack off in the wash.
Although plastisols in general are fine for use on high-elongation materials, the trick is to use the proper type of plastisols on these fabrics. The ink film, once cured, must be able to withstand at least a 300% elongation without cracking. A number of different components within a plastisol give the ink its stretching characteristics. They include the PVC resin (the dried, powered, plastic portion of the ink that makes up its solid components) and the plasticizer (the petroleum-based, oil-like component that makes up the liquid portion of the ink). Together, these ingredients make up the base for the ink.
Specific types of resins and plasticizers are used for high-elongation inks. The characteristics of plastisols formulated for use on high-elongation fabrics are different from those found in standard plastisols in a number of ways:
• they provide at least 300% elongation
• they have a high level of gloss
• they cure at low temperatures of approximately 270° F (132° C)
• the have lower flash or gel temperatures of 170-190° F (75-80°C)
• they can be applied to heat-sensitive fabrics
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