Paper bag printing

I’m printing a large quantity of paper bags – 2,500 – two-sided. I’m having trouble with the print consistency over the folded sections. I’ve packed it to account for the folds, and sometimes it prints fine and other times it’s slightly off. I’m running on a Heidelberg Windmill without guides. The bags are tin ties (, so I haven’t figured out a way to run them using the guides.

For packing, I’ve tried both straight packing – with a strip of paper running down the middle to account for the folds, as well as a few sheets of softer packing on top of that strip. It seems to be work best without additional packing on top.

Is there a better way to pack this to account for the slight variation in running without guides? See the linked photo below to see what happens sometimes.

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I ran a similar bag years ago, you can’t run them on gauges cause the ties will get ripped off, I set the type on a Ludlow 5 times, the bags were thicker than normal ones and after 50 bags I had smashed 4 forms, so I made a rubber stamp out of the last form, that way if a bag went in a little crooked it didn’t smash the rubber, the folds are not very good on these bags, the seams are all over the place, all the makeready in the world don’t help, if I ran them today I would try a rubber blanket taped to the platen which works very good for things like this.

Yeah, I have a feeling there are inconsistencies in the bags as well. I was hoping I could use something as packing that might allow for that inconsistency. I have some dental dam material that I might try. I’m using photopolymer, so I’m not worried about wrecking any type.

Like Dick G said.

All the make ready in the word will not help a product that is not made 100% exactly the same as the one before or after it. You will go insane trying to get them all to look perfect.

If the customer wants perfect then they will need to pay a bag company to print and convert them like the big boys do. Otherwise it’s a hit and miss type of job and all you can do is the best you can do and don’t expect perfection from an inferior product.

if I were you I would get an old AB Dick blanket, they are a little thick but should work, I remove all the packing including the top sheet then use masking tape and tape the blanket to the platen, you will have to back off your impression some but it should work. When I did my job like your bags I did 2000 the first year, next year 5000, then 10000 the last year I did them they got 50000, told them after that to go to a bag company where they convert them after they are printed like Rubicon says. I use an old ab dick blanket but prefer an old patch blanket, don’t know if they make them anymore but they are a little thinner and work even better.

Hello, - fyi - dickg polyfibron patch blankets are still made. ( I ordered some when I was Arlington Litho not too long ago)
jonsel - For printing I have been approached to do the same on my kluge I suggest having a flexo rubber plate made to print with it will help with the inconsistencies of the bags. way back in the day Heidelberg windmills were supplied (new) with a thin rubber sheet for helping with printing halftone images. i think was a little thicker than the dental dam material

always up for a challenge (if it was easy it would be litho lol)

Ted Lavin
artificer Press