Ink showing through on back

Hi everyone,

I’ve run into a problem printing today that’s never happened. The ink is starting to show through on the back side of the paper and I have no idea why or how to fix it. It’s like it’s seeping through but my ink coverage is normal. I’m using Lettra 110 lb paper. Anyone else run into this and know how to fix it?



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Not meaning to be disrespectful, but are you sure it is bleeding through the sheet and not picking up ink from the tympan paper or the sheet underneath in the delivery pile.

Lettra is not sized for offset and does not have the ink holdout the a conventional offset paper would have. If the ink you are using is watered down in any way it is possible but not likely that it is seeping through.
I will be interested to hear how this concludes.

I like to slip sheet when I print on lettra because it is expensive. If you are getting set off, using slip sheets will get rid of the problem and transfer it to the slip sheet instead. I was printing some lettra envelopes last week and looked at the back and it looked like I had set off. I looked on the tympan paper to see if I had accidently printed on it and that caused the set off…nope. Are you sure you are not seeing through the paper and it appears to be set off? I was printing with a dark blue ink and that is was what my problem turned out to be…something with the opacity of the paper causing this? If it is ink you should be able to smear it with your finger.

I struggle with american paper weight ,is this a paper or a card or a board ,assuming its a paper and as mentioned un sized it could be a form of bleed should your ink be too long and the oil is carrying through the sheet , i have seen this on recycled pulpboards . However the practice of heavy impression lends itself to set off proper because the impression can cause like what could be described best as egg box stacking and that is only alleviated as klugette tells of by stacking with interleaved sheets ,not a problem with thirty sheets or so but i would not want to do two thousand .

Peter, 110 Lb Lettra is 297gsm card. I’ve been told in the past that Lettra is un-sized because it was originally created to be a watercolor paper and therefore needed good absorption qualities. This could have something to do with the OP’s problem. Caron, are you running something with heavy coverage and/or deep impression? Can you post a photo so we can see more clearly what’s happening?

Girl with a Kluge — dumb question: what is slip-sheeting? Putting a “dummy” sheet between the tympan and the sheet on which you want to print?


Regarding terms, if the ink is actually going all the way through the paper, in my experience that is called “strike-through”. It is most often seen in very light papers like tissue and napkin stock, which are rather porous.

Caron, what kind of ink are you using (rubber base, oil base, etc.), and have you thinned it or added anything to it? Rubber base ink is designed to dry mainly by absorbing into the sheet, but I don’t remember ever seeing it absorb into the sheet so much that it causes strike-through.

May seem dumb O.K. mine usually are, before somebody else chips in!!! but in the light of the original post, replies, quite correctly offering up slip sheeting/interleaving etc, should the suggestion be asked, have you got anti set of spray, for big solids, long runs with a lot of weight giving set off????? Here in U.K. even mundane platens, in production houses, were virtually always equipped with anti set of spray, which invariably ran from the pressure/blow side of the pump, e.g. Thompsons, H,bergs and similar. V.M,s had their own independant pump running from a counter shaft from the motor. >>>>>> Just a thought from outside the box!!!!

Slip sheeting or interleaving, depending on which side of the old pond you live, is placing a piece of paper in between each printed piece after you print it. You slip/put a sheet of paper on top of your printed paper, after it comes out of your press. Every other sheet is a slip sheet or printed sheet. You can use anything you have on hand to slip sheet. Pages from an old telephone book will even work.

Hey Folks,
We still don’t know if the ink has truly penetrated through the sheet or if it is simply a case of set off from an adjacent sheet in the delivery pile. Caron, can you post a picture or answer the question. Also have you thinned the ink in any way?
Could it be coming from contact with ink left on the tympan?
Regarding offset spray, keep in mind that offset spray is not a drier, just a mechanical way to keep printed sheets mechanically (physically), separated so that the heat and gases from offset printing can vent and the sheets can dry. In a typical letterpress scenario the overall ink coverage and size of a lift, (delivery pile), would be much smaller and lighter.
Simply slip-sheeting by putting a waste sheet of copy paper between the printed sheets should be adequate to prevent set off between sheets.
Caron, still want to hear more from you.
Good luck,