Ink quality

[janezl]

Hi,
certain spot color inks (per PMS) supplied from our ink supplier, cause us problems: very high amount of ink neeed, to achieve color value, close to swatchbook reference. Consequently high dot gain and other print problems occur.
Got a hint, that they might be mixing transparent white into ink, although it is not foreseen as basic receipe.
How could I check incoming ink?
Thank,
Janez

 

[The Heidelberg Guy]

Have all of your PMS mixes to match at 2.5 to 3 Microns, then have them give you a swatch with the micron readings on it. I have had them done like that, but we limited it to 2.5 Micron.

Most bigger ink companies dont nessasarily use the formula that you see in the Pantone guide, they almost always have there custom mixes.

 

[J]

Have all of your PMS mixes to match at 2.5 to 3 Microns, then have them give you a swatch with the micron readings on it. I have had them done like that, but we limited it to 2.5 Micron.

How is ink thickness in microns measured?

Also isn't the target ink film thickness on the press sheet 1 micron for process colors? Shouldn't it be about the same for a spot color?

J

 

[Bob Peterson]

Hi,
certain spot color inks (per PMS) supplied from our ink supplier, cause us problems: very high amount of ink neeed, to achieve color value, close to swatchbook reference. Consequently high dot gain and other print problems occur.
Got a hint, that they might be mixing transparent white into ink, although it is not foreseen as basic receipe.
How could I check incoming ink?
Thank,
Janez

Providing you are talking about the standard Pantone colors in the book, Pantone' ink films in some cases are extremely heavy. Also, if you are buying inks that require an Aqueous or UV coating, different pigments must be used that are resistant to bleed/burnout. The pigment substitutions in some cases do not have the same tinctorial strengths or shades in some cases as the pigment used to create the colors in the Pantone book. Therefore, causing a heavier ink film to be run in order to achieve color.

Every ink company matches and QC's colors differently. In my 30-years in the industry, I have seen used many different techniques to match color. However, none of which were consistant with what a press can actually apply. My current employer does have the process down to a science where the ink is actually weighed and applied at a film of roughly 1.5 mil, more in line with what a offset press can actually run/control.

Over the past couple of years I have seen small ink companies selling offshore inks due to the low costs. These companies are able to mix and resell these inks at an extremely low price. We have obtained samples of some of these inks for evaluation and found them to be as much as 20-25% weaker then what we sell.

I would recommend that you order one of the inks that give you trouble from a different ink company and evaluate it for press performance and color reproduction.

If I can be of any assistance please don't hesitate to shoot me a PM.

Regards,
Bob Peterson

 

[RGPW17100]

Inks heavy in Reflex blue require you to pound it so hard keeping screens open can be a challenge. We really struggle with colors like 293 and 2935. The other problem with reflex is it will dry back red. Red inks to me are easiest to run. Inks with a lot of mixing green tends to mottle on solids. Metallic inks forget it. Get that stuff up to density and keeping screens open is a challenge. Our ink company blames the standards committee. They say that in order to hit some of the colors is almost impossible.

 

[The Heidelberg Guy]

Providing you are talking about the standard Pantone colors in the book, Pantone' ink films in some cases are extremely heavy. Also, if you are buying inks that require an Aqueous or UV coating, different pigments must be used that are resistant to bleed/burnout. The pigment substitutions in some cases do not have the same tinctorial strengths or shades in some cases as the pigment used to create the colors in the Pantone book. Therefore, causing a heavier ink film to be run in order to achieve color.

Every ink company matches and QC's colors differently. In my 30-years in the industry, I have seen used many different techniques to match color. However, none of which were consistant with what a press can actually apply. My current employer does have the process down to a science where the ink is actually weighed and applied at a film of roughly 1.5 mil, more in line with what a offset press can actually run/control.

Over the past couple of years I have seen small ink companies selling offshore inks due to the low costs. These companies are able to mix and resell these inks at an extremely low price. We have obtained samples of some of these inks for evaluation and found them to be as much as 20-25% weaker then what we sell.

I would recommend that you order one of the inks that give you trouble from a different ink company and evaluate it for press performance and color reproduction.

If I can be of any assistance please don't hesitate to shoot me a PM.

Regards,
Bob Peterson

Very true Bob! Although I think that a 1.5 is a little too strong, Heidelberg presses like the 2.5!

A little FYI - We tested 1.0, 1.5. 2.0, 2.5, 3.0, 3.5 and 4.0 Mill of PMS 293. We ran (7) batches of ink looking for shifting in color, from stop and starts, speed changes, 2% water change + or - and the results were pretty interesting. We measured 100 sheets on the Image control for each batch of ink on each run.

(XL105)
1.0 - 4.2 DeltaE
1.5 - 3.3 DeltaE
2.0 - 2.2 DeltaE
2.5 - 1.4 DeltaE
3.0 - 2.9 DeltaE
3.5 - 3.6 DeltaE
4.0 - 4.4 DeltaE

(CD102)
1.0 - 3.6 DeltaE
1.5 - 3.2 DeltaE
2.0 - 2.5 DeltaE
2.5 - 1.9 DeltaE
3.0 - 2.4 DeltaE
3.5 - 2.9 DeltaE
4.0 - 3.6 DeltaE

The CD102 actually handled the heavier ink films more stable, while he XL105 was locked in at the 2.5 range.

 

[Cold]

That is very cool Heidleberg Guy. I would bet if you ran the same test on a komori and man roland, you would find the komori locking in closer to 2.0 and the man roland locking in closer to 3.0.

 

[D Ink Man]

If you compare the ink film thickness of PMS Reflex to PMS Rhodamine, the Reflex takes 2X the film thickness versus Rhodamine to achieve book density. Nuff said, thanks Pantone.

 

[The Heidelberg Guy]

If you compare the ink film thickness of PMS Reflex to PMS Rhodamine, the Reflex takes 2X the film thickness versus Rhodamine to achieve book density. Nuff said, thanks Pantone.

It all depends on who's bases you use.

 

[turbotom1052]

ill repeat my feelings on this issue on this thread even though it may rub some people the wrong way. it is my belief that the pms inks that we buy today premixed are being formulated with either less of a pigment load or with weaker pigments or in some cases perhaps even diluted with transparent white. think about it for a minute here. the pigments in ink probably represent the highest cost of all the components in a can of ink. if the ink companies use less pigment or a weaker pigment it becomes a win, win for them. either way they save money on the raw material and then make more money by selling us more ink. this results in problems for us printers as we now have to run a higher ink film thickness to arrive at the desired color. my way around this whenever possible is to try and take a step up in the pms book. as it turns out transparent white is probably the cheapest thing to manufacture. if possible buy a stronger ink extend it with transparent white to match color without having to run such a thick film.

 

[Cold]

ill repeat my feelings on this issue on this thread even though it may rub some people the wrong way. it is my belief that the pms inks that we buy today premixed are being formulated with either less of a pigment load or with weaker pigments or in some cases perhaps even diluted with transparent white. think about it for a minute here. the pigments in ink probably represent the highest cost of all the components in a can of ink. if the ink companies use less pigment or a weaker pigment it becomes a win, win for them. either way they save money on the raw material and then make more money by selling us more ink. this results in problems for us printers as we now have to run a higher ink film thickness to arrive at the desired color. my way around this whenever possible is to try and take a step up in the pms book. as it turns out transparent white is probably the cheapest thing to manufacture. if possible buy a stronger ink extend it with transparent white to match color without having to run such a thick film.

I can understand why you came to this conclusion, but I can assure you that the highest cost of ink is in servicing it. I (and I assume most, if not all ink companies) want my customer to get an ink that is as near to perfect as humanly possible. As soon as I start adding up the overtime and related costs associated with tech calls, not to mention the downer to plant morale that is related to making a cheaper ink, it just doesn't pay.

As ink makers we try to control the strength of our inks into a window. Too strong and we have issues. Too weak and we have issues. If you are experiencing issues with strength, I highly recommend communicating with you ink manufacturer.

 

[turbotom1052]

cold,
in one breath you understand how i could arrive at such conclusions, and then in the next breath you try to assure me that there is no such thing going on within the ink industry. How is it that you could understand how i arrive at a conclusion like i did if what i suspect is not happening???

 

[J]

No response so I'll ask again...

How is ink thickness in microns, or mils, measured?

The Heidelberg Guy says: "We tested 1.0, 1.5. 2.0, 2.5, 3.0, 3.5 and 4.0 Mill of PMS 293."

Ho did you measure that?

J

 

[D Ink Man]

P A N T O N E Thoughts on 9/11 POST

P A N T O N E Thoughts on 9/11 POST

This explains everything! I wish.

 

[Alois Senefelder]

Ift

Ift

Gentlemen,

In the UK/Europe, ink film thickness (IFT) is measured in - MICRONS


Regards, Alois

 

[J]

In the UK/Europe, ink film thickness (IFT) is measured in - MICRONS

Yes but HOW?

J

 

[Deleted member 16349]

Yes but HOW?

J

J,

I can describe a path to determine the value but there might be other ways.

Normally ink films are measured as grams per square meter. This is done with an IGT unit and a very accurate scale. Ink is printed onto a sample substrate. The rubber covered roller that does the printing is weighed before and after printing. The difference in weight is then determined and since the surface area of the roller is known, one can look up the value of the g/M2 on a chart based on the difference of the measured weight of the roller.

From grams per sq. meter one can determine the ink film thickness if one knows the specific gravity of the ink.

As an example if the specific gravity of the ink was 1, which would be the same as water, then the calculation goes as follows.

An ink coverage of 1 gram per sq. meter.
1 gram of water is equal to 1,000 cubic millimeters.
1 sq. meter is equal to 1,000,000 sq. millimeters.

Ink thickness is equal to 1,000/1,000,000 = 0.001 millimeter. (or 1 micron)

If the specific gravity of the ink is say 1.2 then the ink thickness would be
0.001/1.2 = 0.00083 (or 0.83 microns)

Hopefully I have done the calculations properly.

Note: This ink film thickness is without water. Of course if the same amount of ink is in the film but there is also water, then the total ink film is greater.

It is commonly stated that density is related to ink film but one has to understand that density is more related to the ink quantity in the emulsified ink film. Also density is affected by how smooth the ink is spread in the print.

Hope this helps.

 

[J]

Note: This ink film thickness is without water. Of course if the same amount of ink is in the film but there is also water, then the total ink film is greater.

Because the ink on a press is running with water - does that mean that the actual final ink film thicknesses (as quoted in this thread) are best guess approximations?


J

 

[Deleted member 16349]

Because the ink on a press is running with water - does that mean that the actual final ink film thicknesses (as quoted in this thread) are best guess approximations?


J

My calculation was just provided as an example and does not necessarily represent the actual dry ink film thickness. Although recently when I was involved with Dry Offset, the target was 1.0 to 1.5 g/meter2.

I don't know but I suspect that the ink film values in microns were calculated based on dry ink without water. Not sure what was meant by the values in Mills.

I guess when people state these kinds of values, they should also add the method of how those numbers were determined. It can be confusing.

 

[Al Ferrari]

Some comments on Erik's method:

1. It is a static measurement of a single sample.
2. It is an off-line measurement.

My thoughts are that what is needed is a dynamic, direct, on line, non destructive method applicable to measuring ink OR fountain solution films on the plate or blanket on an operating printing press. Perhaps some form of applied spectroscopy. Does anyone know of investigations utilizing such methods?

Here are preliminary Google searches about such measuring methods:

film thickness spectroscopy - Google Search

dynamic film spectroscopy - Google Search

Al Ferrari