Ink transfer and paper curl
What is your view of the following?
Same ink same press same paper 60# gloss text.
sheet size 25 x 38
1 color black
Fountain solution A sheets come out perfectly flat no curl and virtual no peel noise. Ran 26,000 sheets
Drain and flush tanks now using fountain solution B same plates,ink,paper etc. After about 250 sheets the sound of the paper peeling from the blanket is increasing the sheets are starting to curl at about 2,000 impressions the sheets are too curlly to delivery. Press is stopped the blanket is checked the ink is piling on the blanket. The blanket is cleaned and the run resumed at 2,000 sheets again the blanket must be cleaned. This continued for the duration until the remaining 26,000 sheets of the job were finished.
Fountain solution A required 3 hours for the 26,000 sheets to be ran. Fountain solution B required 5.3 hours and an additional 1,200 sheets to get the 26,000 required.
One fountain solution is high in VOCs the other has virtually none.
Which fountain solution performed better and why?
Last edited by Green Printer; 07-14-2012 at 12:30 PM.
I wonder why !
Hello fellow Lithographers,
Answer: Water Pickup
Variations in F.S. formulation can have a major impact on how much fountain solution absorbs into inks. Fountain solutions with varing amountsof IPA added, or wetting additives can change their reactions with Ink.
PS - I will post some PDFs on this subject later
High VOCs - Best
It sounds like a difference in the compatibility and the emulsification capacity of each fountain solution with the ink.
Fountain solution A with the higher VOC's provided a better marriage of the ink and fount that resulted in your favoring run characteristics. It is surmised that the emulsion formation was a more uniform mechanic producing tiny and consistent water droplets within the ink portion of the equation. The ink had a better ability to hold the fount within its structure over the timing of the run. With better and more fount being contained in the ink, the fount had less opportunity to stray away from the ink median and travel outside to where it could damage, such as the paper curl you encountered.
With Fountain solution B, just the opposite occurred. Poor unstable emulsion, with much larger water droplets and the ability for the low VOC fount to leave the ink portion, and end up in places that were of detriment. In this case, the final destination point for the fount was the stock which resulted in the paper curl. The fountain solution always has to have a place to reside in the offset print process. With Fount B the residence was the paper stock because it was much more unwelcomed, less tied up properly with its neighboring ink.
I don't know if this is a trendy problem with the founts, higher VOC products versus low VOC. But if everything were being equal it is my thoughts, that higher VOC founts would be a better compatibility partner with the ink than a low VOC counterpart.
The good news is this case problem is it can be studied in a lab using some of the modern equipment that explore ink and water relationships. D
In the original post by Green Printer no information is given about the direction of the paper curl which becomes progressively worse until it interferes with the delivery of the sheets.
In your interpretation model which way does the paper curl: up or down?
Hello fellow Lithographers,
Most Offset Paper Grades are printed - Long Grain Direction Paper curl depends also on which side is -- the Felt Side or Wire Side
The low VOC fountain solution ran without issue.
I propose that the low VOC fountain solution was a kind that did not attack the ink, so the ink tack and body were not effected.
Chances are it had better blanket lubrication properties then the high VOC fountain solution.
The high VOC fountain solution, highly likely to be made up of aggressive solvents, has attacked the ink, changing it's properties. possibly the plate was actually running too dry, causing a lack of blanket lubrication & the ink to be a higher tack then it would have been with the other fountain solution causing the issues of the pilling & ink build up.
It also brings us back to the point that although the chemical technitions on this site say that there is no need to have a fountain solution & ink combination developed to work in harmony, this shows that there is a need and chances are the fountain solution that worked was one that had been tested, built and married with that particular ink.
The high voc fountain solution ran without issue. Thesis already offered.
Again, which way does the paper curl in that thesis, up or down?
You have to ask Green Al.
Originally Posted by Al Ferrari
No, the question was directed to you and was regarding your thesis. How could Green Printer possibly know that? Here it is again from my 11:30 AM post:
"In your interpretation model which way does the paper curl: up or down?"