Odd Uneven Impression with polymer plates

UPDATE: I’ve been able to get the impression screws moving and am hoping within some minor adjustments this can be fixed.

Hello, I am trying to print some invitations using a polymer plate and boxcar base. I have been able to work out uneven impressions in the past, but this one is confusing me. I am getting an impression on opposite corners of the plate […]

I have been messing with the packing/makeready with no luck. Usually, the less packing I have the better impression but no matter whether I add or take away, the center of the plate is not affected, only those two corners have a slightly deeper or shallower impression.

I have included a photo that I hope is readable. I am still new to letterpress, so forgive me if the answer is obvious.

image: IMG_6906.JPG


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I can’t really see very much in the photo. I’m assuming this is the back of the printed sheet; could you attach a photo of the printed side?

What type of press? What size of press? What size is the plate?

Have you laid a straight edge (like the edge of your line gauge) across the plate in various places and directions to be sure the plate is flat? (Try to slip a 1/2 inch wide strip of paper under the line gauge in various places, while it is on the plate, to see if there is a space between the line gauge and the plate).

He messed with the Impression screws and forgot that the Platen is a Plane, as in plane surface, if you torq one corner down, the opposite rises up, until the Plane is absolute level, center will not print.

I purchased a roller gauge from John Falstro and this tool helped me set the rollers and parallel the platen. Well worth the $28 I paid.

Thanks, George. I just purchased one and am hoping that will help solve some of my problems!

Thanks also for the other suggestions. I should have checked the plate as well and will do so next time.