Inkjet paper surfaces

[Grandad35]

I thought that it might be interesting to look at the surface of a few inkjet papers, so I put 3 Ilford inkjet papers under a microscope:
Classic Pearl - 240 GSM swellable satin finish suitable only for dye based inks (slow drying)
Smooth Pearl - 290 GSM nanoporous satin finish suitable for dye and pigmented inks (instant dry)
Smooth Gloss - 280 GSM nanoporous glossy finish suitable for dye and pigmented inks (instant dry)

This image shows the Smooth Gloss paper, with the printable surface on the top and a segment of an edge view on the bottom. The printable surface is on the left of the bottom image - there is a similar coating on the uncoated side, but it was out of focus on this image. Since the paper is about 10 mils (250 microns) thick, it gives a good reference for the scale of the images. The term "nanoporous" implies that there should be small holes in the surface for ink to wick into the paper, and there appear to be multiple (approximately 10 micron diameter) holes in the surface. It was very difficult to focus on the holes, as the holes don't appear to be well defined. The holes appeared sharper when viewed through the stereo eyepieces, but since this image is from only one source it is not as sharp. It was also interesting that the holes were not nearly as visible at higher magnifications, apparently because the depth of field at those magnifications was too short to pick up the poorly defined holes. Note that the contrast has been greatly increased on these images to bring out the details of the holes - they are not nearly as obvious in the microscope or on the original. For another comparison, this post (http://www.nifty-stuff.com/forum/viewtopic.php?id=392) shows the ink dots after they spread out on the paper at almost the same magnification.

This image shows the Smooth Pearl paper. It has similar holes in the surface, and also an irregular (larger scale) surface pattern that gives the paper its satin finish.

This shows three views of the Classic Pearl paper. The top is a similar view as given for the other two papers. Since it is "swellable", it isnt expected to have holes in the surface, and it doesn't. It shows similar ripples from the satin finish, but there is a lot of small scale surface roughness that was not seen with the Smooth Pearl paper. The middle is an edge view, showing that the thickness of the paper varies due to the satin finish (the printable surface is on the right on this image). By way of an explanation of why the focus is so bad, these papers have very soft coatings, and they don't cut cleanly even with a new razor blade (the usual technique is to freeze them in dry ice or even liquid nitrogen before cutting them). The resulting smeared surface is at varying heights that can't all be in focus at once. The bottom part is a close up (at 4x the magnification of the other shots) of just the swellable coating. The swellable coating appears to be made from at least two main layers, and it appears to have another very thin layer between them.

If anyone has access to a scanning electron microscope, it would be very interesting to see what the nanoporous papers look like in an SEM.

I looked for information on the details of both nanoporous and swellable coatings, but I didn't find any detailed "how is it made/how does it work" technical references. Does anyone know of any links to such information?

 

[drc023]

This isn't very technical, but it does tell a little about the composition of inkjet papers.
http://www.jetprintphoto.com/c/photopaper.asp

 

[JV]

A paper presenting the New Kodak Ultima Picture Paper:

www.kodak.com/eknec/documents/63/0900688a801caf63/ULTIMAWhitePaper012804.pdf

JV

 

[BlasterQ]

Just when I thought Grandad has coverered everything, here he is again with another excellent post! You just amaze me!

 

[Kenyada]

Great post, Grandad! Having already purchased a box of Classic Pearl for my i9900, I thought it only fair (and technically necessary) to purchase a box of Smooth Pearl for the iP5000. Well, at least that's the story I'm floating at home

 

[Grandad35]

JV,

Thanks for the link. That is an excellent technical paper, as I would expect from a company like Kodak.

The subject of the paper is Kodak's "New Ultima Picture Paper", which has been on the market for some time. I can't find the date of the paper, but the latest reference is 2003 and the link has "ULTIMAWhitePaper012804.pdf" at the end, so I assume that it was logged in to Kodak's system on Jan 28, 2004. The concept behind this paper is novel (at least to me), in that it uses a nanoporous surface layer to achieve "fast drying", but also incorporates a swellable layer underneath the surface layer to achieve improved long term stability.

This concept make sense, and illustrates that the inkjet paper may be more important to a print's longevity than the ink (as has been stated by many others). This ties in with HP's statements that their improved print life is limited to specific HP papers, and could explain why some bulk ink suppliers have said that many of the inks for Canon's new CLI-8 carts are the same as the inks already used to refill the BCI-6 carts. Could the real improvement with the new generation of Canon printers be in a new generation of Canon papers that will be marketed under the same names in the same packages, and which have already been in the distribution channels for some time? It would be a stroke of marketing genius if Canon was able convince us to obsolete our printers and ink inventories, accept "chipped carts" and switch to Canon paper to get about the same improvement as we could get by just switching papers. Is there anyone presently doing longevity tests and who would be willing to buy some new Canon paper and add it to their tests?

If anyone is interested in the Kodak/Wilhelm difference of opinion in testing procedures, this paper does an excellent job of presenting Kodak's test procedures - their position certainly seems reasonable. I have never seen an equivalent presentation on Wilhelm's procedures, so it is impossible to say which camp has a more convincing argument.

Misc info from the paper:
I was incorrect in calling the dots on the nanoporous photomicrographs "holes" - they are apparently "ceramic nanoparticles" that are capable of quickly "wicking up" the ink.
Kodak states that their paper base is acid free and non-yellowing.
The surface on the back of the paper is important to prevent sticking to previously printed photos on the paper tray.
They claim to get excellent performance on all printers with one paper.
Kodak's ratings are for unprotected display in a typical home environment, not for storage in a dark album or behind glass.
Kodak tested several other papers, but they did not present the results. Does anyone know if these results are available?

 

[JV]

Grandad,

Can you see the 9 layers of the Kodak Ultima Picture Paper in your microscope?

JV

 

[Grandad35]

JV,

I'll try to to buy some Kodak Ultima paper this weekend and test it the next time I visit my former employer (who has the microscope). This microscope cost $20,000 6 years ago, and isn't something that I have at home (although I wish that I did). Actually, I would prefer to use a SEM, but they are in the $100,000 range and cost about $250/hr if you want to buy time. This is about the same as it costs to talk to a lawyer, but at least you ... (fill in your own joke here).

As one of the previous images shows, it is sometimes possible to see separate layers, but only if they have different optical characteristics. I have worked on a number of multilayer "coextruded" films, and it helps to have some knowledge of what you are looking for before starting to get a better view under the microscope. For example, EVOH and/or Nylon are commonly used in barrier films, but they can be difficult to separate from each other and the skin layers. Fortunately, staining the edge of the sample with iodine colors the Nylon a little and the EVOH a lot, making them easy to see. In this case, I don't know the "tricks" to make the various layers more visible, since I don't know which polymers are used in each layer. I'll give it a try, but I can't promise anything.

 

[Manuchau]

Thanks for this important info. I've just started using Ilford papers - now I know why the classic pearl takes longer to dry than the smooth pearl. Brilliant!!

 

[JV]

A good reference on InkJet Print Longevity: www.livick.com/method/inkjet/pg2h.htm

JV