Heidelberg PM52 Four Color Process on 70# offset issues

I'm running a PM52 and attempting to do 4 color work on 70# offset. This is definitely within the Heidelberg's capabilities, however I can't seem to get a clear and dense print. Printing to gloss is fine, so I'm thinking that the offset stock just soaks up more ink and I should run the densities much higher. Assuming that the blanket pressures and color densities are correct, is there any pre-press settings I'm overlooking? Should my dot patterns be different for offset stock then gloss to get a more vibrant copy? Should we be looking at color curves in true flow and making adjustments, or should I focus on ink and water only to solve my issue? Any comments will help, I want to get a nice, dense, four color print.

 

You can not get the same result on gloss & matt , no matter what density you use.
if you want the gloss result.....use gloss paper ,
the only thing that can help a little is if you pre-coat the stock and let it dry before you print it.

Good luck

 

As meny says it will never be the same. Higher ink density is not really good as it increases dot gain which is already higher on uncoated due to the rougher surface causing lack of highlights and general 'flatness'. Stochastic screening may help as dot gain is negligble when carry more ink. What LPI is your film/plate output set to? Too high on uncoated is a bad thing, 130-150 LPI for rougher uncoated stock is better.

OGR

 

Thanks for the tips, I will have pre-press look into the LPI and get some actual numbers on dot gain etc. I'm reading that adding some fluorescent ink to yellow, and magenta can create an added "pop" to the image on uncoated paper. Have you tried this at all, I've never heard of doing this?

 

try to disregard the cylinder pressure scale and increase pressure until it prints full. you might often wind up printing certain uncoated stocks at the minimum squeeze adjustment the press is capable of. Your dot gain will increase by using more pressure but you can compensate for this by using custom pre press curves.