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Heidelberg windmill - Inconsistent inking

Hi there fellow presser´s!

I´m running a business card project, and “all of a sudden” the inking seems to be inconsistent. It looks like the rollers are set type high with equal diameter, my packing is optimal, the printing plates are washed out perfect.

I´m attaching a photo. Look at the typography, the dots doesn´t seem to be in touch with the roller´s, i don´t know..

Any ideas out there?

Thanks.

image: inconsistent_inking.jpg

inconsistent_inking.jpg

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It appears the small dots might have been crushed down a bit by impression, so the rollers do not contact them. It also looks like some of the extremities of some of the other characters are also leaving an impression, but not inking.

Perhaps a slight adjustment in Ink roller height will allow them to properly ink. You could test this by putting a thin sheet of paper (.003” copy paper for instance) behind the chase and plate, reduce the impression and bring it up slowly. This will give you an idea if the rollers will contact those areas if lowered.

I agree with John’s assessment that this is a plate failure. Is this a photopolymer plate? I would have it remade.

Daniel Morris
The Arm Letterpress
Brooklyn, NY

Deep impression will kill most plates and lead type or cast lines over time. You could always adjust the roller track, rather than putting anything behind the form. I was always told that was a bad place to make any adjustments.

I would give lowering the rollers just a touch a try so they hit those dots with a little more pressure. They seem to be impressing the paper adequately. I printed a job on a Vandercook yesterday and lowering the rollers fixed the exact same problem you are having.

I have had the same issue a couple of times and the first thing to look at is the plate and see what the areas not printing look like as compared to the ones that are as to height. I do my own plates ad somtimes small dots or type does not come through on the film if the imagesetter it it is set too high then it either is not transfering to the plate or it isnt high enough to pickup ink because of the denisity of the negitive. You might be able to set the rollers closer but you have to be careful as to not over ink the rest of the plate trying to get them to ink.