Rules to live by from the screenroom to the dryer.
By Rob Coleman
Transitioning from plastisol- to water-based processes will require new routines and techniques, from the screenroom to the dryer. Here is a quick snapshot of some rules to live by as you make the switch:
• Because the pigment load of a water-based ink is much lower than plastisol, use an accurate scale when mixing colors;
• Keep inks covered in production and sealed when in storage to prevent evaporation;
• Shake pigment containers on a regular basis – monthly, at a minimum – especially with fluorescent pigments;
• Follow the manufacturer’s instructions when using additives such as retarders, penetrants, crosslinkers, softeners, thickeners, and thinners;
• And, label ink buckets to indicate which additives have been used to avoid confusion when using the inks later.
• Use lower mesh counts (110-156 threads per inch) for solid areas and underbases;
• Pay attention to the thread diameter and percentage of open area, not just the mesh count. Thinner (S) threads will provide optimal results;
• Properly clean mesh to avoid fisheyes and pinholes:
o Remove haze;
o And dry thoroughly before coating;
• Use your scoop coater correctly to apply even emulsion coating:
o Use the dull edge of the scoop coater for mesh counts below 200 threads per inch;
o And above 200, use the sharp edge;
• In order to build good EOM, apply one coat of emulsion on the outer (shirt) side of the mesh and two coats on the squeegee/ink side;
• Dry thoroughly, print side down;
• Consider using a second face coating on the squeegee side to prolong screen life;
• Fully develop the stencil to prevent stencil breakdown from underexposure:
o Exposure calculators are recommended;
o And post-exposing the screen may also be advisable;
• Use emulsion hardeners to extend screen life on longer print runs:
o Allow screen to dry completely prior to applying the hardener;
• And screens must be dried thoroughly prior to production or the trapped moisture will lead to premature breakdown on press.
Did you enjoy this article? Click here to subscribe to the magazine.