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Large image - uneven ink deposit

Posted on Wed, 9 Feb 2005 at 12:38



Printing image 34" wide X 23" front to back. Image is large flood with reverse copy. Printing waterbase ink, using triple duro squeegee 65/90/65. Printing with 255 mesh @ 24newtons. Image is positioned 8 inches from inside front of frame and 5-1/2 inches from inside sides of frame. Using clamshell flatbed with new pressbed. Press will permit min offcontact of 1/4", and have peel set to start half way back through stroke. Substrate is heavy paper stock.

Problem is: image at front and center prints fuzzy, reverse copy fills in and ink deposit looks heavy. Solution has been to add off-contact which cleans up image significantly. But ink deposit is still heavier in the front/center, front most copy is still a bit enlarged due to bleeding of heavier ink deposit. Observation is that adding off-contact lifts just the front of the screen and that changes flood stroke = more f-bar pressure in the front = expressing ink
into the mesh = making heavier deposit.

Any ideas on how I can print an even ink deposit front to back.

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Comments

Anonymous says: Pete, I would try lowering your off contact back down to a minimum, and using a harder durometer squeegee and possibly a thicker ink. I don't know what the viscosity is, but I print waterbased inks all ...

Pete,

I would try lowering your off contact back down to a minimum, and using a harder durometer squeegee and possibly a thicker ink. I don't know what the viscosity is, but I print waterbased inks all the time and they tend to be a little looser than their solvent counterparts.

Max

posted on: Wed, 02/09/2005 - 6:45pm
Anonymous says: Can you delay flood? cycle would be flood/print /lift / change out stock /pull flood/pull print/lift etc. this won't leave ink in the screen to drip through while you are changing stock. You need to ...

Can you delay flood?

cycle would be flood/print /lift / change out stock /pull flood/pull print/lift etc.

this won't leave ink in the screen to drip through while you are changing stock.

You need to make sure the press head is parallel with the table top.

run the ink a bit thicker if it is bleeding through after the flood, or run on a finer mesh screen.

make sure the squeegee pressure isn't bending the squeegee over.

posted on: Sat, 02/12/2005 - 4:58am
Anonymous says: Couple of thoughts: Your press bed may not be level with the master frame. New bed?(affects off contact & peel) Your image to fabric to frame ratio may be low and not allowing the fabric to flex ...

Couple of thoughts:

Your press bed may not be level with the master frame. New bed?(affects off contact & peel)
Your image to fabric to frame ratio may be low and not allowing the fabric to flex and use those 24 newts to your advantage.
Ink may just be too thin.
Flood bar may be rounded and too much down force.
Squeegee angle may be set too high or low.
Squeegee & flood bar may be too narrow for image. Reverses need more squeegee and floodbar to allow the fabric to peel.
Press speed? Allows peel & fabric to flex and not fight the inkfilm release as the squeegee passes.

Hope any of these help.

posted on: Tue, 02/15/2005 - 11:43pm

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