FNO - Fading in black/cyan/"photo" dye based inks

[Nifty]

So glad we have this forum where people can come together and make this stuff happen!

Keep up the great work guys.

 

[Grandad35]

Canonfodder,

Our ISPs seem to be feuding again, as my PMs to you are bouncing back. Do you have a different email address that you can PM to me?

 

[canonfodder]

Grandad35,

Yes, my ISPs email was totally out for several hours. I called them and they already had a recorded message saying "Yes we are down".

They are O.K. now, but I will send you a second address for use when my mail bounces.

 

[fadeaway]

Sorry I am late picking up on this thread -only so much time in a day.

I have to say that this sounds like a useful project and much will be learned about these dyes as you do the measurements and comparisons. Kudos to all who are forging ahead on this.

I still have concerns however about metering of ink and paper effects.

My concern is that the ink density to the paper may also be affected by other ink properties such as viscosity and surface tension, both of which may change the rate of absorption onto the paper stock . Now, during actual inkjet printing, the ink is effectively metered by the head in which case viscosity and surface tension may have a different effect and likely less of one. In addition, the inkjet paper formulations are in a constant state of flux. Even the addition of whiteners may vary and this will impact the spectral response due to their fluorescence. Future measurements may prove impossible to compare to earlier ones if the test paper is changed or made obsolete. Further, papers made in different countries may vary due to production limits at a particular location. I know that Kodak runs their papers off in both Canada, and the USA. Now I want to suggest an alternative approach only as food for thought:

One can for example, measure a known quantity of ink with a pipette and dilute it with a known quantity of water. The diluted ink is then placed into a transparent container to a known depth. A simple container may be a thin tray filled to a specific height. This tray is then placed on a white card and the spectrometer aimed through the liquid surface. Now I am not sure if Grandad35's spectrometer can perform such a measurement because it may require a very specific distance to the ink surface. Nonetheless, a very thin vial may make this feasible.

I have attached a scanned image of the results of a quick and dirty test. In the example, I have used vials that are of equal dimensions. It is actually a pool test kit. The ink was diluted by 400:1 with distilled water, then placed in the vials. The vials were then closed, laid flat on a scanner and scanned without adjustment. The vials have an inside wall spacing of about 7-10mm (they are tapered from top to bottom)

The results are strongly in line with what I had noticed when I replaced the BCi- 6 carts with G+G compatible. That is for the G+G , the saturation is less, and the cyan is shifted more towards green (unadjusted, my prints had a yellow-green cast.). My printer required me to increase the cyan ink lay, and make some hue adjustments.

Consider this post food for thought and not a recommendation of this method. Comments anyone?

 

[Grandad35]

Fadeaway,

It's good to hear from you again.

We agree with what you say about the difficulty of getting a uniform and known ink laydown, and I'm sure that you remember that was the stumbling block when this project was first contemplated. Canonfodder has spent a lot of time developing a technique that measures a precise volume of ink, then deposits that known volume onto a known area of paper in a very uniform manner. He will publish this technique after a few final tweaks are completed. His procedure is simple and elegant, but requires some practice and skill to achieve the desired results.

You are also correct about the importance of the paper. At this time, it is our intent to have Canonfodder run all of the ink lay downs, using the same box of paper. Enough paper from this box will be saved so that future tests can be run using the same box of paper.

It's amazing that you also came up with the idea of measuring the color of the ink itself. Canonfodder created similar samples some time ago by using two precisely spaced glass microscope slides, then filling the gap between the slides with undiluted ink. The color of these samples was very easy to measure with the spectro. The reason that we abandoned this approach was that the color of the ink itself can be quite different from the color produced when the ink is put onto paper. Look at the ink chambers on your C/M/Y carts: the C and M inks pass very little light, but the Y ink is almost transparent. The problem appears to be that the mordants in the paper greatly affect the color that is produced by a given dye - see (http://sonic.net/~dbeebee/IMDI_new/mordants.html) for some extreme examples. It is very possible that this approach might work for pigment based inks, as long as they don't contain any dyes.

 

[fadeaway]

Hi Grandad35,

I have made a number of prints on inkjet transparencies. I have two types one is a swellable polymer, and the other has a nanoporous coating. While I have noticed a difference in the intensity of the images vs inkjet paper which may be a function of the coating formulation, the color reproduction is very similar to that of my photo paper, so I maintain the same hue settings for either media.

I would argue that the mordants should not impact an inkjet image because the ink is absorbed into the nanoporous/swellable polymer receiving layer and does not permeate into the paper layer. In fact most photo inkjet papers that I have come across have a plastic resin base (often polyethylene or polyester) sitting below the receiving layer. I do agree with you in the case of plain paper prints, in which case the paper mordants and even the cellulose fibers may interact with the dye and this may explain the reason for the very different setting requirements for non photo papers. Now having said this, I do think the base layer's reflectance spectrum will impact the image especially if it has whiteners which many of these papers contain.

Have you compared the spectral response of Canonfodder's glass slide method vs a swellable polymer print when the slide is placed on the same photo paper (used as the white card) as the comparing print? I think the swellable polymer would be a better choice since the nanoporous coatings do scatter light on their own.

 

[Grandad35]

Fadeaway,

I'm far from an expert in this area, but I was under the impression that mordants are also included in the top "image" layers. For example, this link (http://www.kodak.com/eknec/PageQuerier.jhtml?pq-path=1870&pq-locale=en_US) states that Kodak uses mordants in one of the image layers above the polyethylene barrier/reflective layer. Is it possible that the inkjet transparencies have the same "image layers" as photo paper? The photo paper's polyethylene layer is highly loaded with TiO2 to give a bright reflective background for the image layers. The transparenciy films would probably be made from clear polyester, but the image layers could be the same on both.

I did not compare the spectral response of the ink itself to the ink on paper. When I get a chance, I'll try some simple tests with ink between layers of polyethylene film and the same ink on paper.

 

[fadeaway]

Grandad35,

Yes there are mordants in that image layer as you point out yet we do not know if or how they affect the color rendering. I would guess that it would be in Kodak's best interest to choose mordants that minimize any shift in hues. Going beyond this particular paper. it is quite likely that other papers may not contain mordants or that the formulations of mordants if they are incorporated, may differ.

I don't have any reliable information on the formulations of the coatings on my transparencies however the swellable polymer type of transparency is an inexpensive "house" brand and I suspect that it would not have such sophistication.

Using any photo paper as part of a testing standard, still has me concerned, due to the variable formulations of these coatings.

 

[Grandad35]

When I get a chance, I'll try some simple tests with ink between layers of polyethylene film and the same ink on paper.

As promised, I tested the color of ink compared to the colors that it produces when on paper. This is far from a rigorously controlled test, but it was "quick and dirty".

I only used C/Y/K inks for the test. A piece of food wrap was spread out flat on a table, then a single drop of each ink placed on the film, spaced about 3" apart. A piece of Kirkland Photo paper was then pressed onto the film and the ink pressed out as quickly as possible. The test was repeated with a sheet of bond paper that I use when printing text in my laser printer. Finally, it was repeated with another layer of film to keep the ink in its liquid form.

The ink splotches from the first 2 tests were roughly the same size. The ink from the 3rd sample was squeezed to get approximately the same size splotches as the first 2 samples, but it was very difficult to keep it from spreading too far. It was pushed back toward the middle to be as close as possible, but the results were from perfect. The cyan and magenta inks were close to the color density of the bond paper, but the yellow was very much lighter (as expected). Each color was sampled with a spectro (a sheet of photo paper was placed under the ink-only and bond paper samples to get the same reflectivity), and the color file retained if anyone wants a copy. For simplicity of presentation, all 9 colors are shown below on the same display. The ink colors are given by the first letter, and the paper is given after the dash as "I" (Ink), "PP" (Photo Paper) and "BP" (Bond Paper).

The increased color intensity of the photo paper over the bond paper or ink alone is obvious, as is the washed out nature of the yellow ink alone. The magenta and cyan inks alone are close to the colors produced on bond paper.

Even though this wasn't a rigorous test, it shows that the ink's liquid color isn't the same as the color produced when the ink is absorbed into paper (especially yellow). It also shows that the type of paper makes a big difference in the final color, even with the same amount of ink. This might make an interesting addition to our other tests (to apply a precise amount of the same ink to different papers) to see the effect of various papers.

 

[canonfodder]

This might make an interesting addition to our other tests (to apply a precise amount of the same ink to different papers) to see the effect of various papers.

Now that is strange!

About 3 days ago, you had mentioned to me that Costco may have started getting its glossy photo paper from a mill here in the USA instead of from a European source. Also, long ago, you had explained to me the effect on color that occurs with papers meant for inkjet photo printing, and how this makes looking at a liquid ink sample inappropriate. This morning as my driver, (wife), was taking me to an appointment, I began thinking about doing comparative ink tests with different papers, and wondered what you would think of that.

I think it is a good idea, especially since we do sometimes have something to print which we would prefer to do on other than glossy, like matte.

I have used Ilford papers in the past for matte and semi-matte heavy weight papers, but the few types that I have are so out of date that Ilford has stopped making them, at least under the names that I have. Ilford marketing must have wanted to pump up the business and came up with the "Galaxie" group of names for their line of inkjet papers, along with nice new box decorations. My paper predates "Galaxie".