November '15

For the Business of Apparel Decorating

Issue link:

Contents of this Issue


Page 77 of 102

2 0 1 5 N O V E M B E R P R I N T W E A R || 73 Low-value colorways and low fab- ric-mass knitted shirts, highly saturated/ transparent colors, and separating ink phases are the primary reasons we are will- ing to fight with flash. The battle becomes formidable, if not impractical, with a low- end, red cotton shirt in high humidity on a cool, uncalibrated press with a distant flash set to fry a low fill-rate mesh, thick stencil, slow moving/buckled blade, and with an ink that which penetrates. Low-cost shirts have lower fabric mass and unfortunately it is nearly impossible to print on air-space—hence our tenden- cy to use coarser meshes and metric tons of pressure. Fibrillation is primarily a re- sult of the finish on short staple-length fibers. Therefore, if there is just a spec of red showing through the most glorious white under-base, it screams of pink. Most of us prefer cotton over blends for several reasons but not for its moisture re- gain—particularly on humid days. Cotton will pick up 35 percent moisture which, besides the toxic solvent fumes, is a major reason plastisol is far preferable on-press to the solvent-bearing/ water-based alternatives. If the press isn't cali- brated with four par- allel planes—made up of the carriage, blade, mesh, and platen—we will invariably need to "over-flash" just to get the most remote ink deposit dry enough to print upon. If the platens are cool and the flash is set at a high temperature, preheat- ing is inevitable, and soon after, so is super-heating. A low fill mesh makes matte-down difficult and smoothness impossible. A thick stencil, although effec- tive if the image is less than ~3/8", screws up any under-base area which is larger. Slow means thick ink, dry surface flaws means rough ink, and if the ink penetrates, we're sunk. PRESS AND FLASH The best way to keep flash-curing a ran- domized variable is to work on a press which is not calibrated. The platen sur- faces are potential heat-sinks, which means we have to use time and tempera- ture to warm them "sufficiently" or they will steal the energy from the ink. Most laminated board, and hard metal surfac- es are far worse heat-sinks than are most synthetic rubber surfaces and our need to preheat is based in part on the thermal conductivity of the platen surface. Once the press is calibrated with a nine- most remote ink deposit dry If the platens are cool and the flash is set at a high temperature, preheat- ing is inevitable, and soon after, so is super-heating. A low fill mesh makes Opposite: Flashing is a delicate process that takes much patience and testing. (Image courtesy Vastex International) Below: Flash-cure units should just gel the ink, which means the resin of the ink has absorbed sufficient plasticiz- er but it is not completely dry. (Im- age courtesy The M&R Companies) TO ADVERTISE CONTACT DIANE GILBERT AT 800-669-0424, EXT. 297 DGILBERT@NBM.COM DISPLAY ADVERTISING The Marketplace

Articles in this issue

Links on this page

view archives of Printwear - November '15