Stock Question 4 you printing experts

[ErnieLail]

Hey guys,

having a little problem...
We are running a job on 20pt board thats recycled content with the white paper laminated to one side...
The original press run looked great customer approved press proofs and we're good to go. The GM ordered the "same" board from a different manufacturer and now the color is horrible. The screens are really trashy and the colors are plugging before we can even get our densities up to the same as the first run. We know that the coating of the board is picking off on the first cyl's blanket, so the press operator moved the yellow to the first unit so it wouldnt be as noticeable. I have looked at the press sheets from the orig. run and the current board with a loop and the screens look muddy (yellow looks orange). And the job has a 100% M/100% Y color and it ends up looking orange/red instead of looking for like PMS 485. If i compare the press proof sheet to our current sheet, the ink densities and dot gain are almost identical, but the red solid isnt red. I think some of the color problems may be attributed to them pushing the magenta to get the red to be redder.

We can pull that job off and put another on that uses a SBS sheet and everythings great again. I've checked the plates with a CCDot and they are correct, any suggestions?

If we check the dot gain on the 50% swatch on the color bar we are around 22%, none the less we built a curve that is taking 14% out of the red mid tones and it looks better.


We are planning on running the same job on a 20pt SBS next and see what we get.

Also for some reason the running order is YMCK

Thanks in advance for any advice!

 

[LSW]

Printing the yellow down first will always affect reds badly as the inks aren't formulated to trap in that sequence, hence running the magenta heavier to achieve a deeper red. Also you will get blacks with a hint of any under color. If you're intent on running the black last a better sequence would be C/M/Y/K or M/C/Y/K.

 

[dimitri]

The mix used in the recycled board is varying and the coating of the surface might vary as well, depending on the machine used on the recycled paper mill. That said, it doesn't really matter if the name is the same; the stock could vary in its physical properties causing runnability problems, even if its color can be the same. You could try the same stock from the same supplier,and request some documentation of the lab results; mills have these data: then you can compare those properties. Also, you could investigate if it picks the top or the bottom surface of that board. Mind you... you are buying cheap board... in a sense you get what you pay for

You could use tack reducer on the ink, so that it doesn't pick up that much of the coating surface... just be careful with the amounts you use. It affects dot gain.

SBS would not pose such problems, at least not as much as recycled board. But do not expect to match the color of the recycled board on SBS. The absorption and hue of the stock is different, and the ink levels required on press are different as well to accomodate the absorption rate. Correct me if you run it on SBS and it comes up right.

Also, 'joggling' ink units to address paper problems is -allow me to say- a bad practise. You'll end up having custom ways for running each order. Too much confusion in the long run.

 

[ErnieLail]

i agree i guess if we would have stayed with the same manufacturer as the press proof we wouldnt be having all the issues we are. The pressroom super says that its picking the coating off the front side of the sheet. Thats why they switched the K & Y plates, so that it would be less noticeable if the yellow unit was first. They are already putting tack reducer in the Y fountain to compensate for the color order change.

 

[duct maestro]

What speeds are you running at? and which ink manufacturer are you using?

 

[ErnieLail]

We are using Superior Inks, not sure on the speed, ill check. How would speed effect the sheet?

 

[SpeedKing]

Hi
how many units does your press have? if its a five colour you could move the kcmy sequence up one unit and then use the first unit to trap the debris by having a plate made with scavenger bar outside the job

 

[Mike LaForest]

All of the comment have merit but the base problem sounds to be a substrate problem. If you have a different board inhouse run some of that under the same conditions if the new stock prints well then get a hold of the paper merchant. Other wise you are just spinning your wheels and nobody comes out ahead where downtime is involved!

 

[SpeedKing]

All of the comment have merit but the base problem sounds to be a substrate problem. If you have a different board inhouse run some of that under the same conditions if the new stock prints well then get a hold of the paper merchant. Other wise you are just spinning your wheels and nobody comes out ahead where downtime is involved!

that's it! get the paper people in.