Heidelberg Inking, rollers or ??? - Help!
We’ve been printing a card job with a large solid (and a pattern on one side) and have run into a problem which we can’t solve.
There is a light streak on the printed piece. We have checked the packing, it’s even. We have even adjusted the packing with tissue, the light mark still appears (surrounded by the darker inked area of the larger issue). We have also moved the plate, it’s not the plate, as it appears in the same place on the paper everytime no matter where the plate is. We have rotated the rollers, we have no reason to believe they are not in the round (we just printed a plate very similar to this in a solid red and it had no light streak).
Look at the photos (sorry for the low quality iPhone pics) do you have any idea what the issue is? We have tried everything! The light streak does move slightly up and down on the form - but not by much. It seems to be right in the spot where the right guide comes up and catches the paper.
It almost looks like a toner streak from a copier.
Help!! Advice appreciated.
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I believe that if you measure from the top of the card to the beginning of the streak you will find that the measurement is the diameter of your form roller. Looks like the form roller is starving for ink. The second form roller picks up a little of the slack toward the bottom of the sheet. If you have a bridge roller, put it on between the two forms and I believe that the problem will go away.
Also make sure that your rollers are not hard or glazed. If they are shiny and slick, it will just make the problem worse because they will not be able to hold enough ink for the solid.
Lineguage: Thank you so much for your thoughtful reply. The total circumference of the rollers is 6.2 (2” diameter). The entire length of the card is about 6.5 and this streak occurs about 2.75” from the bottom, so sadly, by my reckoning, it doesn’t seem to relate to the rotation of the form roller.
Regarding the bridge (rider?) roller, I would give my eyeteeth for one of those; don’t have one. Also, the rollers were new when we bought the press 8 months ago and have seen limited use — don’t seem hard or glazed.
Any further thoughts you have on this are appreciated.
The streak is about where the upper roller is resting on the plate when the roller carriage is at the bottom of the stroke. That will leave a mark when the rollers head back up and the marking is exacerbated by any oil on or slip of the trucks. Keep your eyes open for a rider roller—it’s probably the most valuable extra part you can have on your Windmill.
Since you don’t have a rider roller, try double rolling.
It might work. I’ve had to do that on a 13x18 windmill.
Ron
Ron - I’m assuming you’re talking about skip feeding it, right? Both skip feeding and running it through twice (double bump) don’t seem to make that much a difference with the streak, and the color gets dark pretty quick.
Thanks for everyone’s advice so far.