screen printing > 4 Color and Simulated Process Printing

impact of squeegee pressure on halftone ink deposit

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yorkie:
The problem is that the knit of the textile has a valley area beneath the halftone dot. More pressure reduces the depth of the valley, by pressing down the mountains.

Elliptical dots attempt to be wide enough to bridge between an mountain and a valley. The none proportional ratio screen example I attached orients the ellipse to oppose the orientation of the mountains and valleys. Of course at some some point, the ellipse is not big enough to bridge the gap.

Beyond dot shape would be to have a rip which could define a minimum dot size. When the dot size drops too small, full dots would be removed from the halftone and the density of these dots would be given to another dot which is also too small,to where the second dot would grow to a size above the minimum dot size. So the when the rip outputs a 5% screen, rather than having 100 each at 5%, there would be 50 dots at 10%. For a 1% tent, rather than 100 dots of 1%, there would be 10 dots of 10% and a 1/2% tint would have 5 dots of 10%... Any halftone above 10% would print normally.

EDIT: I should have also mentioned that underbasing is a method of smoothing the mountains and valleys.

RichardGreaves:
How much force does it take to leave a bloody fingerprint on the wall as you leave the building? Will pressing harder, help? How much force does it require for a cross cut saw to cut?

Once you make the SEAL of the blade with the inside, and seal the bottom of the stencil with the substrate - more force is wasted.


Take your squeegee and press hard, harder to make this watch leave the hole in the stencil. Stand on it.  More force just BENDS THE BLADE. The ink in the foxhole is laughing at you.

Of course, with absorbent textiles, angle will force the ink that flows ahead of the lip through the stencil holes deep into the inside or a shirt.

How much can you charge for ink on the inside of the shirt - or the platen?


Remember, the downforce is distributed across the 6" or 14" blade lip AND much of it is invested in overcoming the 7 or 14 or 25 newton resistance of the mesh AND the blade stiffness itself.

EVERY amount of force you don't need is wasted. If you can reduce pressure and it still prints - keep backing off.

Concentrate on as much blade speed/shearing force as possible. Screen printing ink needs high shearing force to get it to move rather than force.

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