Printmaster 52 4-color - Alcolor

I've been trying to resolve a persistent toning issue.

Presently chemistry is 7 oz + 2 oz sub

PH 4.1, Conductivity 1400 (new batch)

Brix 2-2.5

Everything I've read on line recommends PH 4.5 - 5 - 5.5

Photo attached is from a run this a.m. after completely resetting rollers on Sunday. Generally just having this issue in the Cyan Unit. Toning is always nearest the tail of the sheet. I've reset all form rollers from the Heidelberg recommended 3-4mm to -- White 4 (first form), Blue 3.5, Red 3, Yellow 2 (last form), Water is at 4 (Alcolor unit)

Our rotation is YCMK. We run the yellow first down to clean and depowder when turning sheets.

 

Check your densities, form roller end play if any, setting form roller to oscillator, blanket/plate packings. ambient/cylinder temperature, bearings of rollers -had a bad bearing on a roller that made excessive heat and toned-

 

Dear BobG,
Can you send me a clear photo(s) for the whole sheet.
For me it is an issue of lateral movement on one or more of the form rollers.
Switch off all the lateral oscillation on your Cyan form rollers.
You have to inspect for small lateral movement too, and stop this movement.
I saw a similar problem, with only a small movement at one form roller!
Give me a feedback please.
Good luck.

 

Bob, the working p.h. of the solution is no longer as relevant as it once was. Modern fountain solutions are buffered for stability. To move the ph a measurable amount up or down, using a modern fountain solution, would require a significant amount of either addition of chemistry. or a dilution of chemistry with more water. The little bit of movement you would see in the ph reading doing this, would result in a big swing in conductivity.
My suggestion to you would be this..... Begin by recording readings of your tap water at various times of the day. Be sure to let the tap run for a bit before drawing your sample. If the average tap water conductivity reading comes in really high you may be in need of reverse osmosis water. Once you've established an average conductivity reading for your tap water, you'd want to then mix in the smallest amount of fountain solution suggested by the solution manufacturer. Do NOT yet mix in any alcohol subs. Adjust the amount of fount until you come up with a conductivity reading app. 1000 higher that whatever your average tap water reads. Once you've arrived at that starting point you can then add your sub in the smallest amount recommended by the sub manufacturer. Be sure to add the mixed solution to the water tanks that have thoroughly cleaned out with a complete flushed out water system. This would be a good starting point. There is a good chance that you may have to add more fount mix or sub, but you want to creep up on the right ratios. Remember that the addition of more alcohol sub with alter your conductivity readings to lower conductivity, so you want to be sure and measure BEFORE adding the sub. Once you arrive at the proper mix you should NOT just think that all the work is over. Ive seen fluctuations in tap water that go up and down from season to season. You want to track these deviations unless of course your willing to go with reverse osmosis water, which will ALWAYS give you repeatable results. Get your fountain solution right and see if that helps with your toning issue. Once you've got it right you will want to keep it right by regular dumping of the solution and cleaning of the system. If you were to start with fresh solution, and a clean water system with the conductivity reading lets say 1200 then you would want to change the solution when the conductivity exceeds about 2000. DAILY monitoring of conductivity would not be excessive.

 

Bob, I would not advise yellow down first UNLESS your running a first down yellow, and then not as a default sequence. Instead address your powdering issues that require your running yellow down first. Running yellow first to clean powder off on the yellow blanket is like putting a band aid on a gunshot wound.

 

A true classic, Mantman!

 

Hey Bob, looks like bad rollers. I've had similar problems with the pm52-5 I run. It also started with cyan, we replaced the rollers and problem was solved. Approx 3/4 of the way down the sheet and it goes all the way across the sheet as well . We run kcmy, I like to use the 1st unit as a duster but sometimes a 5th color or varnish prevents that.....Good luck!(I've been running the pm52 for 12 yrs)