PH on paper

[Alex Arriaza]

im wondering if there is a cheap procedure to measure the ph of the paper or any procedure that i can make in the facility to measure it.
Thanks

 

[gordo]

Try:

TAPPI Website - Surface pH measurement of paper , Test Method T 529 om-09

or this:

pH Testing Pen [64000] : Future Packaging Store, Time Capsules, Archival Supplies & More

best, gordo

 

[Asures]

I regularly use the pH pencil. It is what is known as a "Litmus Pencil."

I have had inconsistant readings with the pens as the tips have a tendancy to retain paper fibers from the frequent checking. The Litmus Pencis I have found to be extremely helpful in shops that call me in when combatting calcium carbonate issues or premature plate ware / plate blinding issues.

The pencil can also help in identifying problematic stocks that might contribute to delayed drying of inks because of extreme acidity or extreme alkalinity content.

See the link below.

http://www.sigmaaldrich.com/catalog/ProductDetail.do?N4=Z264849|ALDRICH&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPEC&lang=en_US>

Best Regards,

Aaron Sures
Gracol 7 Expert
Pressroom Specialist
Gans Ink & Supply Company
(323) 867 -3677 Direct Cellular
Printing Ink, Eco Friendly Inks, Sustainable Inks, Environmentally Friendly Inks, Gans Ink Home

 

[GazKL440]

Just this week using an imported cheap bond i had issues with oxidisation that i believe was related to paper ph.. every time i stopped on a changeover the plates showed spotting etc, to the point where i gummed the plates when stopping to avoid wasteage.. it did not happen on the coated stock i was running beforehand or the different coated stock i used on the job after.. my assumption was that the acidity of the paper was affecting the ability of the fountain solution to correctly protect the plate surface?? am i correct??

 

[Asures]

Based on what you experienced, it sounds as though the stock's pH was certainly out of the neutral range.
It's rare that you encounter an offset sheet that has an ecessively acidic pH but more so Alkaline. Typical printing stocks vary in pH from 6 - 7.5 pH. What you were seeing was probably the calcium carbonate being leached out of the sheet, attaching itself to the blanket, and between blanket and plate contact - it creates either sensitivity or in longer runs it can buff away the plate surface.

The calcium carbonate is used a filler and brightener in the manufacturing of offset stocks.

The coated sheet you ran was probably in the neutral range.

Take a look at this article from Sappi Paper about the effects of calcium carbonate when printing.

Best Regards,

Aaron Sures
Gracol 7 Expert
Pressroom Specialist
Gans Ink & Supply Company
(323) 867 -3677 Direct Cellular

 

[GazKL440]

Thank you Aaron... that is pretty much spot on to what we experienced... fortunately it was only 100,000 impressions, so only one shift of headaches We are having some issues with calcium build up on the edges of our rollers tho, going to a full size sheet on the press creates watering issues about 2" in from the edge of image, requiring some adjustment of profiles to keep a solid at 100 percent... its irritating but you work around it, and quite possibly only a new set of rollers will completely fix it, as calcium and lime rinses seem to be a short term solution only..

 

[Asures]

Gaz,

Something that has really worked for me in the field when encountering calcium carbonate issues / stripping issues of the roller train is the good ol' fashioned Copperizing Solution. If you have any copper rollers in the ink train, the calcium carbonate will leach itself to the rubber inkers and throw off the ink / water balance by making your rollers Hydrophilic (Water Loving) instead of Oleophilic (Ink/Oil Receptive).

The copperizing solution wil make all rollers within the ink train ink receptive and reduce the flooding on the edges as mentioned. Calcium fixes are good but they're just not the same - especially if you have tarnish on the coppers that are forcing the press operator to walk the tight ink / water rope. Bad rollers certainly don't help but if you have play in the water forms and ink form stripes, the rest is down hill.

I'm assuming that you run Komori's by your name? GAZ L 4 40?

Hope this advice helps.

Best Regards,

Aaron Sures
Gracol 7 Expert
Pressroom Specialist
Gans Ink & Supply Company
(323) 867 -3677 Direct Cellular

 

[GazKL440]

Yeah we have a handfull of komori's and some smaller heidelbergs... I have noted some discolouration on the copper rollers, especially the rider in the dampening systems of the 2 most affected units (cyan/magenta) on the 40" i run... all rollers are in reasonable condition and set correctly, when our local roller supplier next drops in i will see if they supply a copperization solution...

Thank you for the advice

 

[spider]

Make your own "litmus paper" Ha! HA!

1 Chop the red cabbage up with a sharp knife.
2 Crush it with a "pestle and mortar" OR put it in a food mixer and grind it.
3 Add a very small amount of water.
4 Decant the blue liquid (pour the liquid into a clean glass).
5 Soak some blotting paper in the blue liquid.
6 Let the blotting paper dry out.
7 Cut the blue papers into small squares.
8 If you add a little bit of vinegar instead of the water, you will end up with red litmus.

Found this on this page
Indicators

 

[Alex Arriaza]

ok i just bought a ph marker and apparently everything is normal, the paper is at 7PH, im not having any problems right now with the printing but a couple of months ago i had a problem with tinting, i change the fountain solution, the inks everything but the paper, im pretty sure it has something to do with the water/ink/paper ph balance, im i right?

 

[spider]

Acid-free paper is paper that has a neutral or basic pH (7 or slightly greater).
It addresses the problem of preserving documents for long periods. Paper made from
wood-based pulp that has not had its lignin removed goes yellow and deteriorates over time.
When exposed to light and/or heat, the molecules in the acidic paper will break down even faster.

The bicarbonate is added in excess, to supply the paper with an alkaline reserve to provide protection
from further attack by acids remaining in the paper or supplied by the environment
In order for paper to last at least 100 years it must have an alkaline reserve of 2% or more.

Why do today's alkaline papers contain so much calcium?
It is cheap and it gets the job done.
cost less than Titanium Dioxide, calcium provides the same benefits it's enhances whiteness, opacity,
and an alkaline pH that keeps the paper from going yellow.
A typical alkaline paper is 15 per cent by weight calcium.
According to industry experts, this is going to remain the same or get even higher,
so calcium buildup problems are not going to go away.

If the pH becomes too acidic, the solution will start dissolving the aluminum oxide non-image area.
If the pH is towards the neutral or alkaline side,
the desensitizers such as gum Arabic will stop working properly

Temperature also influences conductivity.
As the temperature goes up, the conductivity goes up, as temperature decreases,
so does the conductivity. A good rule of thumb, is for every 10° F change in temperature,
conductivity will change by 100 micromhos

Ha! Ha! .......I could go on and on

 

[Alex Arriaza]

Thanks for the info, but i would like to know if the properties of the paper are transfered in some way to the fountain solution or the opposite way, i believe that the solution that touches the paper in the impression roller are dragged with the paper outside the press, so the paper needs to be in certain values of PH so it doesn't have problems with tinting and post press handling, the thing im trying to understand is what are the chemical reaction i should be careful with in the process so i don't have post press problems in the future, can variations in the fountain solution due the paper conditions change the final result?
Thanks

 

[spider]

yes.........
acid-free paper may be treated with a mild base (usually calcium or magnesium bicarbonate)
to neutralize the natural acids occurring in wood pulp, and it may also be buffered to prevent the formation
of additional acids (as may develop from the application of sizing).
and Calcium buildup in the red ink unit you can use a calcium-free red ink and calcium fighting or a calcium fighting fountain concentrate

 

[mfallona]

pH of Paper

pH of Paper

There is a quick and dirty pH pen from Preservation Technologies.
The re-order phone number is printed on the pen: 1 800 416 2665.
Acid paper will turn yellow and neutral or alkaline paper will turn blue.