Paper moisture/gas ghosting issue?

We recently were running a four color job with gloss aqueous coating on a 40" Mitsubishi press. The job is printed on 80# gloss coated text. The skid of paper when it was removed from the press looked like an ocean of waves after the first pass. During the second pass there was wrinkling that needed to be addressed and was cured. After the job was finished, there was a noticeable (and I'll call it gas ghosting) effect where the back of the sheet images effected the front side and likewise the front images effected the back of the sheet. It almost looked like the sheet was debossed. The pressman was quick to point out that he kept the pile heat at 90°F. I'm at a loss as to what would create this effect. Anyone experience something similar?
 
Hi Joel. A few questions:

Was the sheet cold before you started the job?

Have you had any other gas ghosting problems in the past with the same ink?

What ink are you using?

Why do you hesitate to call it gas ghosting since that is what it is? (not trying to be a wise guy. I just want to make sure I didn't miss something.)

Dave
 
Hi Dave,
Thanks for your interest. The paper was run over a period of days so the paper had plenty of time to acclimate to the pressroom. There was no difference in the appearance of the paper that was run on day 1 to the paper run on day 3 or 4. As far as gas ghosting in the past, virtually none, although there was a job run about a week and a half ago that appeared to have very slight gas ghosting. You had to look really closely to see it. Other than that instance, no problems with this ink in the past. We were using Supreme Ink and Amalgamated International coating. Here's another interesting tidbit. There was a companion piece to this latest job that we could not run due to the job that I refer to being on press. We gave it out to a local printer using a Heidelberg 40" w/coater. They were supplied with the same stock. All the paper came from Case Paper - Novalith 80# gloss text (Have not run this paper in 4 years). This other company used Superior Ink and C&A coating. The only reason I hesitated using the term gas ghosting was because it's been a while since I've seen it. Also, the debossing effect is something I have rarely seen. Any and all insights are greatly appreciated, Joel
 
Hi Joel,

Sounds like I'm not going to be much help. The wavy stock sure seems like a moisture (or lack of) issue, but I believe you already realize that. I've run into it mostly with stock that were run right off the truck that's why I asked about the temp of the paper.

You mentioned the other printer did the companion piece, but you didn't say if they had any of the same problems. I'm assuming they didn't.

I kind of figured you described it the way you did because you hadn't seen it in a while. We use Superior ink (Biolocity line) and I haven't seen gas ghosting in years. (we don't have coaters, but varnishing is normally even worse for gas ghosting)

Hopefully it's a one-time problem. Maybe just the way it was stored at the warehouse or maybe it got super cold during shipping.......etc... (I'm still leaning toward it being a paper problem) I've always found that these weird problems always seem to happen in the winter.

Sorry I couldn't be more help.

Dave
 
I am not sure if it would be gas ghosting if you are using aqueous coating, that is highly unusual, coating a job almost always eliminates ghosting, it sounds to me like the sheet is being distorted by the action of the ink drying. the only solution I could suggest is to use a heavier stock, or if you are using a non anilox system you could try less coating.
 

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