Calcium Problem

[dwanehollands]

Hi there,

We're having quite a bit of difficulty with on press ink-water balance performance. We get water marks across the cylinder and have checked and rechecked our roller settings numerous times. They are that close to being perfect it just doesn't make sense that we would be having this major a problem.

An ink representative (not our current one) suggested the other day on a visit that it could possibly be calcium contamination in the ink rollers. We use RO water before we mix our fountain solution, so we know the calcium is not coming from the water.

But we haven't done a calcium clean on the press - ever - I think. It's about 3 years old. So I'm guessing that there's a good chance we have a calcium problem.

However, when we look at the rollers I can't see any white/calcium build up. Could it possibly still be a calcium issue, even if I can't see any coating on the rollers?

Thanks for any input!

regards,

Dwane

 

[Daniel Mazlo]

Hi Dwane,

I take it this is a sheetfed machine??
You really should try to de calcify the rollers at least once a quater depending on the work load of your machine of course.
This will at least prolong the life of the rollers. The calcium is probably coming from the paper although there is a small amount of calcium in your inks too.
Watch the pH of your fount too, it may be to acidic and this is whats leaching the calcium out of the paper.

Good luck

Dan

 

[jlind]

Calcium Problem

Dwayne:
Have you tried washing the rollers with water and vinegar? Removes calcium as calcium acetate.
Have you tried adding a little isopropyl alcohol to the fountain solution to see if the watermarks go away?
Is the durometer of the rollers correct?
What is the etch and the concentration?
A complicated problem.
John Lind
Cranberry township, PA
724-776-4718

 

[Alois Senefelder]

Poor Discription of your Print Problem !!!

Poor Discription of your Print Problem !!!

Hi Dwane, What do you mean " Water Marks across cyl." ????

Do you mean in the Print Areas ie solids ?? Are the solids showing "Wash Marks" at the leave edge ??

1 Are you RUNNING to much WATER - as the Plate Cyl. rotates does it look SHINY with water - the correct look should be a DULL SHEEN, the water in the Plate Grain !!

2 A good sign of the Correct Ink/Water balance is --- A 1mm Scum line at the leading edge of the plate - even right across the plate. Check this at a Press stop

Regards, Alois

 

[Tom_print]

Dwane,
I'm guesing these water marks, are of about a 1mm thick line across the sheet?
Is it hapening anywhere on the sheet, or if you were to measure the diameter of the water form do the lines roughly line up from that distance from the lead edge of the sheet?

Do a calcium flush, this should be part of your weekly maintaince anyway.

Have you altered any chemistry of late?
Are you running the water% higher for any reason then you used to?
Are you on metal or poly plates?
What % IPA do you run with?
If you are running low IPA have you changed low shore hardness metering roller?
(page 3 is a graph that shows the effects that the shore hardness of metering rollers has on the tonning - water window - density drop
http://www.boettcher.de/PDF-Dateien-engl/FA/FA-ProAqualis-engl.pdf

I will say, we have had this happen when we tried to get out IPA % level down very low, basically we were having to run the water % up high and have the metering rollers backed off a little to allow the lower vicosity fount to get through the nip. and what we noticed was the pressmans best freind (water window) had shrunk so much that there was a very fine line between tonning - water window - flooding of water , so much so that one minute your running fine the next you would have fine water lines running horizontal on the sheet. say if you were running a solid green, the lines would appear either very faint green or even paper whit, were it had washed out so much in a 1mm thick line that no ink was accepted there.

Tom

 

[Paultheprinter]

Hi dwane,

if you cant see any white build up on your rollers then there wont be enough to give you major issues, the only pre-requisit is that you may need to run the rollers after washup to evaporate the left over solvent/water, if when there dry there is no white patches then your ok. In previous threads you noted that you dont re-harden your ro? is this still the case or did i misunderstand ? As for calcium in the ink i thought that was an urban ledgend as sheetfed paste ink runs such a thin film that filling them was un-neccesary. My point on roller marks is to check side play in ink and damp forms, these can cause thin bands of dry lines across the cylinder when the roller catches up with the change of direction.

Paul

 

[dwanehollands]

Thanks for responding everyone!

Thanks for responding everyone!

I'll attempt to respond to everyone as best I can.

Daniel. I didn't realise that high acidity in fountain solution causes calcium to leech from the paper. Our pH is around 3.6. Now the range for the fountain solutions is 3.8pH to 5.0.

Tom_print. Yeah the lines are about 1mm wide. And one of them is about 65-70mm away from the grip edge, which is the diameter of the form roller. We are getting some that are bigger such as 6-7mm aswell. Very erratic.

We've been testing Amerikals Wetstone +SF and Think SF founts for last 6 months or so. So we've been making lots of changes in an effort to eliminate Alcohol. But we're back to 5% alcohol at the moment, but still having problems. Alcohol didn't improve it at all.

We run Kodak Thermal Direct metal plates. Now I can't seem to find my hardness meter. I usually strictly put it back in my office after every use, but I can't seem to find it. We did put new metering rollers in and subjectively I thought when I was handling them, that they don't feel that soft. They were manufactured quite a while ago.

We've had to up the water a bit to prevent catch up, and it's like you said, there's just about no window between catchup and washout. It's incredibly unstable.

Thanks for that Bottcher paper too! Very interesting read. So they were talking about the duro of the water form roller helping to increase the window when they compared using an inking roller compound to their special water form compound. They were referring to the water form directly, but didn't really mention the effect of the metering roller. I always thought that the metering roller was the most critical in the mix. Also our pan roller is chrome. So our configuration is Chrome Pan>Rubber Metering>Chrome Transfer>Rubber Form.

So yeah Tom, your explanation of the problems your press operators were having sounds like us!

J_lind. Yeah we're running a wash on our rollers with Bottcher Calcium Fix as I type. Seems everyone recommends it.

Alois. Didn't know that about a 1mm stripe on the lead edge of the plate, shows that you were running perfect ink/water levels. I'd assume normally that I wasn't running enough or that there was a problem if I saw that.

 

[dwanehollands]

I don't think it's a calcium problem...

I don't think it's a calcium problem...

Ok, an update. Ran Calcium fix on the rollers. Washed up a few times with roller wash and water.

Pulled a print. No improvement whatsoever. So I PaulthePrinter was right I think, that if you can't really see it, chances are it's not causing a problem. However noted that the once a week regular calcium clean is a good idea anyhow.

FOUND MY DUROMETER!

I did a reading on the metering rollers which were put in about 6 weeks ago (meaning the hardness is probably the same now as it was 6 weeks ago). I'm getting measurements of 28 and 29 degrees consistently.

I thought they felt a bit hard! I just opened a box of 'old metering rollers' that were in the press for about a year and they measure up as 24-25 degrees shore hardness!

What kind of shorehardness should I be targetting for our metering rollers and dampener forms? Would it better to get them down to 20 degrees for my metering rollers? Increase that window even more than ever?! Would the roller be stable enough at that softness. What about water form rollers? Could they be as low as 20 degrees, or would they just get flogged out too quickly and mean more regular replacement?

 

[CKL]

Double your check your fountain mix. I have seen mixing stations (dosatrons) cause problems. Roller chillers as well can be sensitive, they can amplify the smallest problem.

 

[dwanehollands]

We think it might be the Ink Form to Oscillator

We think it might be the Ink Form to Oscillator

OK, an update.

We've dumped fountain solution, flushed with water and remixed RO with DIC Aqualithe Conditioner (hardener 0.5%) and DIC Aqualithe XLE fountain solution @ 2.5% strength. Running 5% alcohol.

No change.

However, one thing we forgot to do was check the ink formes to oscillators. I noticed that one roller wasn't touching properly (form 4) and then adjusted that and Forme 1 (which was only a 1mm stripe) and we saw a dramatic improvement.

Not perfect, but a lot better.

But as you know, adjusting formes 2, 3 mean taking out all the rollers to get access to them. So we're going to spend the rest of the day setting rollers and print tommorrow.

Does that make senes as to a cause to the problem?

Also we notice it repeats (although not as pronounced) once. Once close to the grip edge and then in the middle of the press sheet. The stripe marks are up to 6-7mm (quarter inch-ish) on this job that we're noticing.

 

[Tom_print]

You want the metering rollers to be around 20 -22 shore hardness.. for low to no IPA printing
that way you can still run a tight nip, but the lower viscosity fount can still make its way through the nip + there generaly more hydrophelic... were as if you had a harder metering roller but the same nip, the fount fights to make its way through.

Brissetts are under a different belief to boettcher about the shore hardness of the water form. Brissets beleive that if you go too low on the shore hardness of the water form, the roller itself doesn't last that long, since its in contact with the plate all the time.
That water window, should be greatly improved though when going from a 30 shore hardness too 22 shore hardness metering roller.

Also make sure the printer has used the correct bearings on the metering rollers, not the same ones that go on the inking rollers. was speaking to one of the printers today, about this problem we had a few years back that came out of no where after new metering rollers went in , it seems the printer put the standard ink roller bearings on the metering rollers, and was pushing the water % very high to fight scumming on the edges.. in which case brought the water marks accross the sheet.

 

[ronaldogu]

Hi,

I was facing the same problem, and was looking for the solution, which I found it here, therefore, I thought to thank all of you.

Great job.

 

[dwanehollands]

Dramatic Improvement

Dramatic Improvement

You want the metering rollers to be around 20 -22 shore hardness.. for low to no IPA printing that way you can still run a tight nip, but the lower viscosity fount can still make its way through the nip + there generaly more hydrophelic... were as if you had a harder metering roller but the same nip, the fount fights to make its way through.

Great, we had ordered some new metering rollers for stock earlier and there was no rush on them. But I'm hoping that they haven't made them as we've put in a request to get them made to 20 degrees shore hardness. On units 2-3 we've got old 25 degree metering rollers. But on unit 1, 4 we've got 30 degrees metering rollers.

Black unit is putting a graduated stripe about 6-7mm (quarter inch-ish) at about 70mm (2.7 inches) from the grip and then repeated just after half the centre of the sheet (lateral marks). Only shows up in the image area. We noticed a poor spot>CMYK mix in the job and re-mapped in pitstop which eliminate the black channel in the area we were struggling with and we were able to get the job out with a great result. Job after that had minimal black coverage (keylines and text only) and so we were able to get them out too.

And so before we attempted those jobs, we had pulled out decks 1-3 and delgazed by hand (weren't glazed anyway), cleaned the ends, checked bearings and then re-installed and re-set.

We noticed on most units that ink forms 2,3 were barely touching the transfer rollers. (you could even spin some). Other rollers up the chain needed more pressure too.

Also checked the duro of our water form rollers. (new from January) and they're 25 degrees. Which is pretty soft yeah? Or are Bottcher talking about softer than that?

That has also dramatically increased our ink/water 'window'. We're still getting those faded black roller marks on unit 1, but it's got a really hard metering roller in there and I think that's the cause.....thoughts?

Also make sure the printer has used the correct bearings on the metering rollers, not the same ones that go on the inking rollers. was speaking to one of the printers today, about this problem we had a few years back that came out of no where after new metering rollers went in , it seems the printer put the standard ink roller bearings on the metering rollers, and was pushing the water % very high to fight scumming on the edges.. in which case brought the water marks accross the sheet.

Very interesting - I'll keep that in mind. Yeah the bearings are those two-row kind that are exposed. (they have a pivoting case)

 

[Alois Senefelder]

Hi there,

We're having quite a bit of difficulty with on press ink-water balance performance. We get water marks across the cylinder and have checked and rechecked our roller settings numerous times. They are that close to being perfect it just doesn't make sense that we would be having this major a problem.

An ink representative (not our current one) suggested the other day on a visit that it could possibly be calcium contamination in the ink rollers. We use RO water before we mix our fountain solution, so we know the calcium is not coming from the water.

But we haven't done a calcium clean on the press - ever - I think. It's about 3 years old. So I'm guessing that there's a good chance we have a calcium problem.

However, when we look at the rollers I can't see any white/calcium build up. Could it possibly still be a calcium issue, even if I can't see any coating on the rollers?

Thanks for any input!

regards,

Dwane

So it wasnt true you set the "Rollers " perfect ???

 

[dwanehollands]

Touche`

Touche`

Yes Alois...Touche`.

We were going on the assumption that the settings to the transfer rollers were fine. We had been experimenting with Dampener roller settings for a month or so and were obsessing with the dampener form to steel setting, metering roller to pan, dampener form to plate and inkers to plate. This is where we have had problems previously and so we assumed that it was where the cause of the problem was. Those were the settings that were "close to perfect".

 

[Tom_print]

Dwane,, not sure if your roller layout is similar to our press , but instead of taking all the rollers out to check form 2 and 3 too oscilator you simply take out water form and 1st form that way you can see the 2nd form too oscilator stripe easy.
Same thing goes for checking the 3rd form to oscilator, symply take out 4th form and you can then see 3rd form too oscilator stripe

We have always gone on this principle , Once you have had to re adjust the forms to plate twice they will then need adjusting too the oscilator.

 

[RaymondJPrince]

Did you pull dry solids and wet solids with cyan at a density of 1.40. If you hve those sheets I would be happy to look at them and give an opinion.

Ray Prince

 

[keldrewett]

I'm in sydney give me a call. I am happy to help you mate.
Not that hard!!

 

[Alois Senefelder]

re Touche !

re Touche !

Hi Dwayne, We all make mistakes !! I always check Dampening roller train by "Inking- up" then check the roller dwell "Stripes" It's easy enough to wash-up after via the Inking roller train. This then " Guarantee's Perfection " !!!!!!!


Regards, Alois

 

[jbeniston]

If you are having problems with ink stripes in the print you should start by:
measuring the position of the stripes from the sheet edge. Divide the measurement by 3.143 and check to see if any of your ink form rollers or dampener are close in diameter to the result. If they are change them.
Make sure that any end float in the rollers is absolutely kept to the minimum. There has to be some play or you would not be able to remove or install your rollers. If you have a mechanism to make the ink form rollers oscillate side to side for "ghosting control" make sure this is locked with the rollers centred. Plate inkers can be as low as Shore "A" 25 degrees but more normally will be 29. When they are 10 degrees above this they will be useless.
Make absolutely certain that the roller and dampeners adjustments conform to the press manufacturers specifications and start by setting to the oscillators first. It is permissible to set the 4th ink form roller 1mm lighter than specs against the plate.
Post treated R.O. water is the way to go. Your pH seems a bit hot. The value should be in the area 4.5 - 5.5. It would seem that the fountain concentrate you are using is not really suitable for R.O. water. You should find one that can give you the correct pH at the recommended dose i.e 2oz per u.s gallon. Mix exactly one gallon in a clean jug and find out. When you have the good mixture check the conductivity this will give you a value to aim at in your system. When you are running alcohol free the dampener settings are ultra important. Shore hardness should be around 25 deg Shore "A". Refrigerate the solution to 10.5 celsius in the tank it will be 12.5 when it gets to the press. Use exactly the manufacturers ammount of alcohol substitute. If they recommend 3 -5 ozs/glln start at the lower value and increase by small ammounts only if you need to.
If you do have a calcium problem it is pretty much a dead cert that it all came out of the paper. The calcium can go right down to the core. You can only remove it with a regular calcium wash using the correctly specified chemicals for the job. The fillers in modern papers is all calcium. The strong acid of your fountain solution is responsible for leaching it out during the run.
So set your rollers to specs, mix the dampening solution to a less acidic level and see what happens. Make sure that the ink ductor rollers are correctly set and are not "thumping". They can cause a shock in the ink train resulting in a shock mark.
Check you blanket packing and make sure that it does not extend over the tail edge of the blanket cylinder and that it is of the right height. You can cut the tail edge packing sheets in wavy line or even in a series of triangular cuts (looks like sharks teeth). This helps to reduce the shock from the tail edge of the blanket.
Last but not least, if all else fails see if you can run the image completely off the plate in the problem areas. This will eliminate the "water margins" at the gripper and tail edges.
Did you run a dry solid? Are the marks still there?
Get help from your suppliers.