Inconsistent print quality

I’m sorry for having problems two days in a row, but here’s another phenomenon that I’m not understanding. These two drop caps (48-point Rondo) were printed one after the other – same lockup, same ink, same paper, same packing, same everything – yet the print quality is markedly different. What could have made the difference? Are my form rollers out of round? How do you know when they need replacing? When I adjust the roller height, there is a bit of difference (maybe 2 points) between the height at the ends and the height in the center of both form rollers.

This was printed on a Vandercook No. 4 with packing consisting of 0.021″ Kimlon, 1 sheet of 0.006″ oiled tympan paper, and a 0.007″ Mylar drawsheet. The paper was Epson Velvet Fine Art, which is 100% cotton with a coating for inkjet printing. It is 0.019″ thick, for a total thickness of packing plus paper of 0.053″. I do try to feed the paper and turn the cylinder in the exact same way.

A closeup of the photograph is available on Flickr.

Thanks again for your always helpful comments.


3 thoughts on “Inconsistent print quality

  1. Gerald Lange - May 26, 2010


    I see this three times a week. That is how many courses I teach. Other than mechanical problems, which include aging rollers, it comes down to form lockup inconsistency, improper ink or ink viscosity or additives, incorrect ink film transfer, wrong roller height adjustments, impression not in sync with inking strategies, or just plain old wrong substrate.

    A big list but absolutely controllable. Start by switching out the paper (especially if it a new unknown factor).

    But you already really know all this. Two points? Replace the rollers. I haven’t experienced problems with RotaDyne (ever) and they have the Vandercook specs (they made rollers for Vandercook when it was Vandercook) and they are in Chino.


  2. Barbara Hauser - May 25, 2010

    Thanks, Kyle. You’re right about the soft ink. The last time I used this particular ink was to print a large solid area, and I neglected to stiffen it for text. Another factor might be the coating on this paper, which is designed to receive inkjet pigments, not oil-based ink. But what I really don’t understand is the variation from print to print. These two prints were made one after the other, with no changes in inking, impression, or anything else that I was aware of.

  3. kyle van horn - May 25, 2010

    I commented on your flickr photo but I’ll double up my comments here so that the Vanderbloggers can chime in as well:

    It looks like soft ink to me. I use Magnesium Carbonate to stiffen my ink, a problem most common when it’s warm outside (and in). Different inks are different consistencies naturally, so some are worse than others.

    Sometimes too much ink causes the same problem, though it then becomes a battle of full coverage vs. clean printing. The larger the type it is, the more ink you need, and the more problematic it becomes.

    Less ink, and a little stiffer will often solve most problems, though I’ve been forced to trip between prints in the past to get the density in ink required.

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