screen printing > Screen Making

something I learned yesterday

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BorisB:
Today we had visit from Sericol rep.
We compared emulsions side by side. Same mesh (63 t/cm), same settings on machine coater (2/2).
We user RLX and he is trying to sell me Dirasol 915. Both have 38% solids.
Results:  RLX EOM 14% Dirasol 915 EOM 60%. How is this possible? I always beleived that same solids should give very similar EOM.
I guess I was very wrong.

Today i will repeat the test, I will additionally weigh emulsion that went on a screeen. My girl that did coat those screens later told me, that consumption of 915 was huge..


Boris

Colin:
My thoughts are that it would depend on the viscocity of the emulsion.  A thicker more viscus emulsion would force you to coat thicker on each side.  That in turn should give you a higher eom when dried.

It would be interesting to see what that emulsions detail hold and press life are.

keep us informed.

squeezee:
It might be thixotropic, it thins under stress and puts a lot more on the mesh.

alan802:
Yeah, I would think the viscosity and thixotropic characteristics would be the culprit for different eom's. 

On this note, I built a 4/6 on a 135/48 using Saati PHW Red last night and it was measuring 280-300 microns overall, eom was 220-240 microns.  I'm going to do some experimental printing with it today.

squeegee:
Viscosity is a big factor for sure, I also don't think the solids measurement is always an apples to apples comparison for emulsions.  Case in point, the PHW red Alan is using builds up more EOM for me with fewer coats than my day to day emulsion.  The solids content on paper between the two only varies by 2%, but the PHW red is far more viscous.  I know I've used the solids content as a point of reference like you are before but it doesn't always hold true.

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