drying issue

First of all - I am a newbie in offset industry. Said that...

I am facing a "copying" problem, if I can call it like that. Probably there is a technical name for it but I can't remind it now.
Apparently the sheets are not dry enough and I get some ink from the underlaying sheet to the top one. I have lowered the speed to 3500, make small stacks, be generous on the powder but still I get some "copying". And I have a dryer unit on my Pro machine.


What do you guys do to prevent that ?

Is it coated or uncoated you have prolems with. Check your powder device is working properly (does it spray al all). Speed is not an issue, I alway run on 8000 SPH. At wich density's you print solids.

Hi Marc !

It is coated (both glossy & mate). I use the standard density CM=1.4 Y=1 Bk=1.8

I will make some tests on the powder unit to check it.

Thnx for helping...

I asume it's only on black build with CMY and K. Check if the total amount of ink doesn't get higher than 320%. What brand of ink you are using.

Hi Marc,

Found the problem:
The powder spray unit was not working at all. I did activate it and only air was spraying but no powder regardless of the max position.
So I disassembled the powder unit and one piston (solenoid) which opens/closes the powder was blocked. So I open it clean it and now it snows in powder.

Thnx for helping...