Inkjet Smudging

An AICC Member Asks:

We supply litho labels to corrugated manufacturers, and recently we have had an inquiry as to our clients  finding success on ink jetting a code on to our supplied labels.  It appears when they inkjet it has a tendency to smudge or smear after being applied to our aqueous coating.  We have even done testing on knocking out the coating as well as just printing on blank stock with no ink or coating, and they end up with smudging issues.  The obvious answer in my mind to to use a different ink on the inkjet machine, however I understand how that additional set up, may not be feasible from a cost or production standpoint.

I am curious if you are familiar with this process, or might know of other instances where this may have been an issue and how that may have been resolved.

Tom’s Answer:

Dyne Testing of the raw stock prior to Printing/Coating may help you find an answer.

This can have a profound impact on the wettability of the base stock…with or without your Inks and/or Coating.

While Dyne level is a more critical issue for the Plastic folks that print and/or label…..it does play a major part in Paper/Paperboard Printing /Coating as well.

This test is of particular interest to me due to the issues you seem to be having with smearing, smudging, etc…..indicates a significantly “tight” sheet or High Surface tension.

Inkjet fluid inks depend on a fairly decent level of porosity for successful transfer and post application curing to be successful. I have experienced first hand in both the Plastic and Paperboard Converting Industries.

I would also ask your client if they have the ability to Corona Treat the InkJet Print surface, which would create a reduced surface tension as well.

As you know, most of our membership is like you folks….their Clients are the ones date coding, postmarking, etc. the printed labels or litho laminated products.

Since the inkjet does NOT seem to work well, even on the raw board, you are off the hook a bit from my standpoint. I would ask the Inkjet supplier to test your raw board, with and without ink/coating,  and supply their finding to you for transferring to your Mill Supplier…..I would also suggest a quick test of Corona Treatment (flamer) just prior to their Inkjet to see if the outcome is significantly better. Your ink supplier may have a primer material in Varnish or Coating that could be printed on that patch to aid as well.

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