Offset/Offsetting/Set-Off - Occurs when the printed ink from one sheet adheres to, or partially transfers, onto the back side of the next consecutive sheet.
Fountain solution pH is too acidic
Reduce amount of concentrate or switch to less acidic solution.
Fountain solution conductivity is too high
Remix solution to lower conductivity.
Too much reducer added to ink
Running too heavy ink film
Lower ink setting. Switch to stronger pigmented ink to achieve desired density with thinner film.
Coated or non-porous paper
Use spray power and/or infra-red dryer.
Sheet not being handled well in delivery
Adjust joggers and other sheet handling devices to achieve smoother delivery.
Rack jobs to allow less weight within each pile of wet printing.