Less Dot Gain at Press

[Racer Tees]

Well.  A lot has changed around here.  Will be good for the long and short term IMO.  Purchased a Starlight and Kruzer from M&R.  Wanted to go used auto, but I need to build my credit back and this seemed like a no brainer considering the junk I had been printing on.  I used to keep the gain settings at 38% in Photoshop and my on screen separations were pretty spot on to my actual print.  Today's print seemed to come up way light.  When I brought it in the office it seemed that I had to pull the dot gain back to 10-15% in PS to get on screen to match my print.

So here's what has changed.  Just trying to consider what could be contributing to less dot gain at press.  Not saying less is a bad thing, but I just want to understand why and where my changes are coming from.  Especially since we changed a few things at the same time.

1. Starlight.  Obviously I have much better stencils now than I did in the past.  Not sure how this could contribute to less dot gain on the press.

2. Kruzer.  It isn't that Brown POS that I was running.  I can run my off-contact a bit lower and the press doesn't flex like the Brown.  Plus we are running on rubber tops now.

3. Single Black vs. Multi-Black output.  My 1430 had some banding issues that took me a few days to overcome.  In the end I see that I can get a much better quality film running single black instead of multi-black.  Is it possible that most of my dot gain was on the film instead of at press?

Just trying to gain a better full understanding of why I will see these changes.

[jvanick]

since you are running manual I would think your culprit is the single black vs multi-black.  The multi-black was likely creating pooling and making your dots 'bigger' due to the pool spreading.  You may have also been unknowingly underexposing with the old unit and making the dots bigger  as well.

if you can compare a 'before' upgrade screen & film and after, you should be able to see this with a loupe.

depending on how hard you're pushing, the rubber tops could cause a bit of gain due to them being soft, but I really think that your problems are in the screen, and not at press.


-J

[Colin]

Yep, sounds like you had dot gain on your films. 

Simple test:

Take an old film you made with halftones using the multi-black.  Create a new film of that same file with the single black.

Compare dot sizes using a loop.  If every thing looks "close enough" to the same, then now make a new screen for each film.

Compare dot sizes there with a loop.  Then get them on press and see how closely they look when printing.

Oh, make sure to use the same squeegee for testing