 Re: Any advice for first job printing on nylon drawstring bags?
Just delivered sixty 3-color, tight-registration black nylon string bags that the customer was thrilled with.
Ink: Wilflex MX System PMS matched colors using QCM XOLB-158 X-Tra Opaque Fast Flash Creamy Glacier White as the mixing white.
Nylon Catalyst : Triangle Tri-Bond 1180-66 additive. Approx. 10% additive to ink by weight. (The container had been previously opened and used for past jobs, so I heated it in the microwave for about 45 seconds to get things "flowing". I did have to throw out some of the material that had hardened beyond recovery. Still, the catalyst worked fine. I find I can get only one use out of a Union Nylobond container before it hardens in the bottle and needs to be tossed. The Tri Bond definitely has a longer shelf life. Also, fresh catalyst would have made the ink thinner, so it is probably wise to wait for an hour or so under those circumstances until the mixture thickens up a bit.)
Screens: 156 mesh
Squeegie pressure: medium light. The lower pressure produced the sharpest image. No flood stroke. Double hits are a no-no. No underbase used or required. Nylon does not absorb the ink, so the colors stay bright--even on black.
Dryer speed: fast enough to ensure that the surface temp of the bags did not exceed 300 degrees F.
Flash Unit: Raised to approx. 7 inches above the bag.
Flash Temp: MAX 275 degrees --approx. 15 seconds--which is enough to gel the ink/additive mixture. Bags were flashed twice--once after printing each of the first two colors. (Flash was required. Printing wet-on-wet on Nylon will produce a fuzzy image.)
Bags were printed manually and were placed on separate surfaces after they exited the dryer, but it was not necessary to "catch" them, as they felt dry to the touch and did not stick to other bags. Bags were left out to air-dry separately for 72 hours before being packed for delivery.
With all the flashing, the job does go slowly, but you must finish before the ink hardens in the screen (8 - 10 hours). It will be necessary to strip down the whole job and clean *everything* (screens, spatulas, etc. as well as toss all inks) at the end of the day. The catalyst-treated ink will turn solid when it dries, and it cannot be removed. However, as long as the ink is still "wet" you can clean the equipment with the same solvents you use for normal plastisol jobs. | 
