Duplexing curl and show through woes

Tony, Two things to consider and try.
If the only apparent change to your process is using the brayer in place of the pressing roller I would eliminate the brayer. Just hand rub the two sheets together and place under weights.
You could be laying down to thick of a glue layer. Bonding of the sheets can be accomplished with a surprisingly thin glue layer although the ‘open’ time will be short.
When duplexing two sheets of the same stock there usually is not a curling problem. That is why I am concerned about the amount of glue. the sheet accepting the glue may be to wet and will curl until the moisture balances out.
let me know your thoughts on these two items. also keep your original run under weights and see if the curl relaxes although that may not help with the sucked emboss. problem.
Call me if you like:)
Jon Drew/Mpls
Duplexing & Beyond
drewpress.blogspot.com
612.270.6449

Hi Jon,

Thanks for the response. Your site is wonderful! Gonna lose myself there for a while, for sure. What a find.

I will definitely check the glue flow and play with that, I didn’t even consider it. So obvious.

Thanks again and I will be in touch!

Tony

Lower humidity in heated winter environments can amplify problems which seem manageable in other seasons. Make certain that both sheets being laminated have had the same exposure to the environment in which you are working. If one comes out of storage are and the other has been in a different environment, that can give you differing starting internal humidity, and cause curling. Also if one is exposed to the adhesive longer before laminating, that can be a problems. too.

John Henry

Are you stacking them in a perfect stack, all facing same direction?

My thinking is that if the glue is too thick (as 2001fred brought up), and the raised portion of the emboss is directly beneath the cavity of the next piece on top…
It could be possible there is a little dimpling effect going on, where the raised portion of the emboss is pushing the paper above it UP ever so slightly, sort of pitching a tent with the emboss high spot…..?

I’m not totally sure of a fix, but if that is indeed the cause you could possibly work around it by alternating and stacking with a blank in between- or some other way to install a spacer that creates a bit of cushion around the raised portion.

Additionally- are these going under a cutter post-glue? (During the cutting might there be a bit of an issue from the clamp? Or are you die-cutting them?)

Happy to report that we adjusted our glue flow and that took care of 99% of it! We bought a cold laminating press and use it to do the final squeeze. Cheap but it does the job.

The paper we have used is always 100# Mohawk Superfine cover from the same carton in the same environment, and the time between applying the glue and mounting is almost nil. Most of our paper is in our inventory for a while before we get to press.

We have been stacking them with a blank in between, since the first run. We’ll see if this final cut makes the impression or not. But we’re going to start using a die cut. It’s too nerve wracking putting them under the cutter!

:)

I’ll keep you all posted on the final results. Thanks again everyone!

Hi - Just curious. Do you laminate them with the grain in the same direction or cross grained?

i have found water based glues will tend to curl a bond, cross grain or not. for small jobs i have found 3M “super 77” or this type of adhesive will not penetrate as much. the sheets stay flat. cross grain mounting is a must. only an amazingly light spray coat is needed

Hello everybody!
It looks like I have the same exact problem with double-sided business cards!

2 ericm:
I also used 3M spray glue once and it gave great results .. except that the whole workshop was covered with a thin layer of this glue. But yes - the glue was good, albeit expensive in our area…

2mactony:
But for large runs, I have to use cold glue. And yes - I have exactly the same problem. Apparently due to the fact that the glue is based on water. After drying, the image of the front side of the business card appears on the back side. And this effect is enhanced after the final cutting on the guillotine. This was not the case with 3M spray! At the same time, I also use a manual rubber brayer to glue the sheets …And by the way, thanks for the thought of using a cold laminating press!

Apparently there are two solutions - to select the right glue and spend money. Or use die-cutting instead of guillotine trimming …

neket

I have duplexed Letterpress printed sheets forever, and never had a problem with off setting.
What type of glue you are using? Brandname ?

I use Eukalin 5183 L400 glue
This problem occurs when I do my prints with deep impression… I will try to take a photo today

Does that glue shrink when it drys/sets? That could be pulling down the embossing. And don’t discount the possibility that the glue formula changed. (no help, otherwise)

Neket, this is an extremely watery Disperson Glue for corrugated Cartons , you should use Planatol 152, Planatol makes Adhesives and Glues for Bookbinding for a Long Time, they know what they do

typenut

Thanks for the tip .. I’ll try to find a supplier here in Russia))

I used to do a lot of duplexing…. and can tell you that it’s all in the glue. PVA and other modern adhesives are easy to use, but do tend to curl. Any adhesive that forms a plastic film can lead to curling under some humidity conditions.

The best glue I found was old fashioned starch paste applied with a wide brush, and then dried under pressure in a book press. It’s a slow process, but the results are worth the effort.

You can use Japanese Nori, or make your own. Bookbinder’s paste also works extremely well

I’ve gotten good results with 3M ATG 976 2 sided tape on some duplexed announcements. Do all 4 sides, and a couple down the middle, and put the 2 pieces together, then a final trim. Easy enough, and no drying time.