Printwear

Recognized Supplier Guide ‘18

For the Business of Apparel Decorating

Issue link: https://nbm.uberflip.com/i/1070168

Contents of this Issue

Navigation

Page 40 of 202

36 || P RI N T W E A R O C T O B E R 2 01 8 Why do screen-printing inks crack? Curing ink is like cooking a steak. If you want a rare steak, you have a hot re and quickly turn the steak over before re moving the steak fro m the re. A well done steak requires a lo wer te mperature for a longer ti me for the heat to cook through the steak. We want all inks fully cooked. So, the con - veyor should have a long hood rather than a wide hood so that the shirt will typically be under the hood for at least one minute. If the ink picks off with your ngernail, then you have a rare steak. Thicker ink deposits (steaks) require more than one minute for the P V C ink to melt into the gar ment. ROGER JENNINGS, R JENNINGS MFG CO. INC What is a simple way to remove old adhesive from a screen before re-stretching? The si mplest, most effective way to re move adhesive is by using a product that has a thick consistency. This will ensure that when brushed onto the surface of a screen, it will re main in place without running onto the edges of the fra me. Leave product on the fra me for 10 minutes, scrape the glue off with a putty knife. If the screens are ex- ceptionally old, reapplying re mover might be necessary. Prior to re-stretching, si mply rinse the screen. This method is the perfect alternative to grinding and sanding old ad- hesive that can lead to da mage of a fra me and release of che mical dust. SHELLEY MARKUS, RHINOTECH Can I eliminate ash curing? Yes, in most cases. In most cases, a person ashes and prints a second or more ti mes because insuf cient ink was printed on the rst pass. Even a coarser mesh does not deposit suf cient ink. Print, ash, print is like piling one brick on another until the pile of ink is tall enough to produce the desired opacity. The solution is to replace liquid e mulsion with capillary l m, which is bet ween the mesh and gar ment. Capil- lary co mes in different thicknesses and can be la minated for a greater thickness. For ex- a mple, 50 microns on 83 or 110 mesh deposits suf cient ink to avoid having to ash and print again. Most screen printers say they print 120 one-color prints per hour, but only 35 shirts when printing, ashing, and printing again. So, capillary can mean a signi cant increase in productivity. ROGER JENNINGS, R JENNINGS MFG CO. INC How can I eliminate pinholes from my screen? Pinholes have a li mited nu mber of causes, which any shop can eli minate. A minute or t wo of extra care can ensure a consistent, pinhole-free stencil. 1. If you use diazo direct e mulsion, be sure the diazo po wder is co mpletely dissolved before adding it to the e mulsion. Check the sensitizer bottle's white cap liner for undissolved diazo particles. If you see the m, recap the sensitizer bottle and shake it again. 2. Avoid air bubbles in sensitized e mulsion. The necessary, vigorous shaking of the di- azo bottle creates a head of foa m which, if blended into the e mulsion, is dispersed as air bubbles. Allo w the dissolved diazo to stand about 15 minutes before adding it to the e mulsion. If you are in a hurry, after shaking the diazo, uncap the sensitizer bot- tle. Drape a s mall square of ne mesh over the mouth of the bottle and secure it with a rubber band. Tilt the bottle just beyond the horizontal and pour it into the e mulsion. Air bubbles can also be introduced into the e mulsion by stirring in the diazo so - lution. After mixing the sensitizer solution into the e mulsion, close the contain- er and let it stand for a mini mu m of one hour until all air bubbles have dispersed. Al ways stir until the color of the e mulsion is unifor m. This is the best way to ensure thor - ough mixing. ( Don't forget to scrape your stirrer across the sides and botto m of the e mul- sion container, so that all the e mulsion is mixed with the diazo sensitizer.) And don't forget to use a clean stirrer. 3. Poor screen preparation is a major cause of pinholes. Particles of dirt, dust, and che mi- cal re maining on the fabric during coating will be trapped in the e mulsion. These spots will block light fro m hardening the e mulsion beneath the m so that the e mulsion in these S C R E E N P RI N TI N G Pinholes have a li mited nu mber of causes, which any shop can eli minate. A minute or t wo of extra care can ensure a consistent, pinhole-free stencil. (I mage courtesy GraphicElephants.co m)

Articles in this issue

Links on this page

view archives of Printwear - Recognized Supplier Guide ‘18