plate blinding

[Randy]

I work on Heidelberg XL 102 SF 6 color. We have an issue with plates blinding, the plate begins to stop accepting ink after 25,000 impressions or so. It is always the red plate (magenta or rubine, or any ink with a lot of rubine). We can run sometimes 35,000 to 50,000 before the job becomes unacceptable.

I can clean the plate with plate cleaner, and get more life out of the plate. The image is not wearing off, it is just not accepting ink.

We run virtually all board stock like .016 to .024 C1s. We use Alden and Ott ink.

The last shop I was at used Toyo, and we ran gloss text for the most part, and never had this issue. We could easily run for 150,000 impressions on our plates with no issues.

My boss tells us this is a nationwide issue, and is because of the paper. Anyone else experiencing this?

TIA

 

[rapid3]

I think it's because of calcium buildup in the rollers.
I had the same problem with Toyo HyUnity ink.
Like clockwork, at about 35-50M impressions the
magenta would start blinding.

 

[gordo]

I work on Heidelberg XL 102 SF 6 color. We have an issue with plates blinding, the plate begins to stop accepting ink after 25,000 impressions or so. It is always the red plate (magenta or rubine, or any ink with a lot of rubine). We can run sometimes 35,000 to 50,000 before the job becomes unacceptable.

It may not be the paper. It may be the ink because trace amounts of calcium can be found in some ink formulations with higher levels typically present in magenta. Consult with your ink supplier.

best, gordon p

 

[Dan Roll]

There is an experiment you can run that will help determine what is going on. When the plate first starts to blind, try adding a little linseed oil to the ink, inline with where the blinding is taking place (the intention is to make the ink more liquid). If this restores the transfer you do not have a calcium issue.
If this does not restore the transfer then there is likely a build-up of some hydrophilic material on the plate image.
You do not mention the fountain solution you use or the manufacturer of the plates....

 

[A BETTER WAY]

Another check is to drag your finger across the plate, blanket, and ink form. If it feels chalky or very thick it is an ink problem. Could be calcium or too much drier or too much flashing off of ink solvents.
It boils down to an ink and chemistry problem.

Gordo is correct about the calcium in the ink. This has been and continues to be big problem with pigments that come from China and India especially red pigments.

 

[GJOHN]

Plate Blinding

Plate Blinding

From my 25 years of experience, it could be Calcium problem coming from both ink and paper and tap water if you are not using RO water. The fountain solution has a major roll in aggrevating it. Recently I found out that some plates are more sensitve to the calcium issue. I agree with Dan Roll that an ink that transfers better will help. Also a magenta that is made with low Calcium pigments will help. Perhaps your fountain solution rep. can recommend a mild acid product with a Calcium block in it. Your boss is right that this is an industry wide problem, but you can minimize it by using the right ink/fount/plate combination.
Any questions, plelase call.
George John
269-216-8088.

 

[Alois Senefelder]

White Transparent Extender

White Transparent Extender

Hello fellow Lithographers,

The use of precipitated calcium carbonate (PCC) is as an Extender in printing ink, which is one part of the "Additives" in printing ink.


Regards, Alois

see PDFs

 

[A BETTER WAY]

Hello fellow Lithographers,

The use of precipitated calcium carbonate (PCC) is as an Extender in printing ink, which is one part of the "Additives" in printing ink.


Regards, Alois

see PDFs

Extenders are typically used in offset inks to lower the cost of manufacturing.

Talc, clay,water,calcium carbonate ,solvents are all common extenders.

With extenders ink mileage goes down and troubles increase.

Make an ink without the extenders. It will cost a little more and the trouble go away.

So now what cost less to use? A cheap ink with low mileage and lots of problems or ink that cost a little more has better mileage and No problems.

 

[CD102]

Let me ask a question. Does the addition of talc reduce ink misting? Or would it have been better for printing quality to ask for a reduction in extenders so we could have run a thinner ink film?

I hate to say it, but a think a lot of bottom-line guys can't get past the cheaper initial cost of the extended ink. They don't get that the more expensive ink might actually print as many units with higher quality/less defects.

I had this debate with my department manager many times and I think for the most part he agreed with me, but the big decisions were centrally made far away and our input was not needed. Sometimes you felt like you were working in the old Soviet Union.

 

[herbert]

Hi

Change inks supplier.....defintely a ink problem..We just moved from Sun to Flint because of this reason

 

[mrheidelberg]

Let me ask a question. Does the addition of talc reduce ink misting?

or does it just make the ink smell nice !!

 

[GJOHN]

Plate Blinding

Plate Blinding

Alois Senefelder,
I agree with your statement that there is some opaque white is used in (very few) PMS colors to clean it up but that used to be TiO2. Cold set web and heatsert process colors will have some clay and fillers. But we are talking about Sheetfed Process Colors and there is no Calcium Carbonte or PCC in it. The rubine pigment is the only pigment that has Calcium in it but ink makers use EDTA to tie it up or use a low calcium pigment. I will be surprised if Sun or Flint or any ink manufaturer use Calcium Carbonate in SF process colors. I welcome the comments of ink formulators and chemists who agree or disagree with me.
Like I said in my last post we can help you to minimize the effect of Calcium Carbonate coming out of the paper with the right ink formulation and fountain sloution and proper check and measure of pH and Conductivity of press ready fountain solution.
George John
269-216-8088.

 

[Alois Senefelder]

re Plate Blinding

re Plate Blinding

Hello fellow Lithographers,

There are two main reasons for plate blinding, 1) abrasion of image 2) accumulation of gum on image.

A quick technique --- while the press is printing, lift the inkers, run 10/12 blank sheets into delivery. Drop the inkers and continue printing 10/12 sheets, then again lift inkers and run more blank sheets. Repeat this operation 4 or 5 times during the print run, will get the plate to print cleaner and sharper.

Second technique --- strengthen image area by using "Asphaltum Wash Out"


Regards, Alois

 

[mgk_print]

Blind Man's Bluff

Blind Man's Bluff

Hmmm...quality in equals quality out. Using quality rubber can diminish these problems. Stripe rollers everyday, check squeeze often. Not trying to sell, just sayin'. Paper companies are not going to quit trying to make white whiter.

 

[kkvimal79]

We are facing same problem after 2000 impression printing on back side of the paper with conventional ink.