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Best Practice Tips for Water-Based Inks

(September 2015) posted on Tue Oct 13, 2015

Rules to live by from the screenroom to the dryer.


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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:



Ink Department
• 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.

Screenroom
• 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 Degrease;
     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.


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