With today’s shorter lead times and quick turn expectations, ink drying in conventional offset printing can be critical to getting your job out the door on time. Many shops promise 24 hour turn-around on orders that may include printing 2-sides, cutting and shipping.

 

So how do you optimize ink drying to allow for quick backing up of a job?

  1. Print the lighter coverage side of your job first.

How do you avoid set-off when printing heavy coverage?

  1. Avoid excessive ink saturation! TAC (total area coverage) should not exceed 280%. For example, when we print a rich black, our preferred build is 100% black, 40% Cyan, 30% Magenta and 30% Yellow – a TAC of 200% ink coverage. Tools are available in Photoshop and other graphic design programs that allow you to optimize and reduce TAC. Most of these programs will use grey component replacement to take over-saturated dark builds down to a manageable TAC level – without significantly impacting the print output color.

What else should you watch for?

  1. Use ink additives to accelerate drying sparingly. This is one of those cases where a little is good, but a lot is NOT better. Conventional inks will dry by absorption and oxidation. The ink may feel dry on the surface long before the full thickness of the film is dry. Cutting stock that is not fully dry may result in smearing along the cut edges if you cut through a wet ink film. Additionally, too much drying additive may result in chalking of the ink pigments on the surface or may result in the ink drying on press.
  1. If you are running heavy coverage, consider running shorter stacks and increasing the amount and/or particle size of your spray powder. This will provide more air space between the sheets.

 

For ink to be fully dry, it may take 24 hours or longer depending on the amount of coverage. There are things that can be done to reduce drying time or at the least get the sheet “dry enough” to back-up or handle in post processing. Being aware of the potential issues is the first step in trying to avoid them.