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Author Topic: Specialty Papers and Some - Mark Segal's Review  (Read 1410 times)

Alan Goldhammer

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Specialty Papers and Some - Mark Segal's Review
« on: March 11, 2017, 05:02:41 PM »

Mark does his usual thorough job on reviewing some old and new papers.  I've been printing on Hahnemuhle Bamboo ever since it came out some years ago.  I like the warm tones but of course one needs to be considerate of what image to print on it.  In the write up, Mark mentions it is biodegradable and hence not a paper for long lasting images.  I would be careful with this term as any paper derived from natural sources (cotton rag or tree-derived alpha-cellulose) is biodegradable. The right enzymes and the right conditions will break down the cellulose and hemi-cellulose polymers to there saccharide components.  It's just a matter of time.
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Mark D Segal

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Re: Specialty Papers and Some - Mark Segal's Review
« Reply #1 on: March 13, 2017, 01:15:31 PM »

..............  In the write up, Mark mentions it is biodegradable and hence not a paper for long lasting images. .........

Hi Alan, Nope, that's not really the intent of what I said, but I can see now the risk of misinterpretation. The biodegradable bit, correct. But not the remainder. I said - in jest actually, but perhaps a bit subtle - "good for prints we donít intend to keep". So it's not that they can't be long-lasting with this paper, it's just not to worry in the sense that if we don't want to keep them they can be biodegraded. The intent of the point is that however long we want to keep them, the decision is ours and the substrate can be environmentally friendly. I wonder whether alpha-cellulose is as environmentally friendly in terms of its ultimate disposal, as I have seen the biodegradability claim made for bamboo but not for alpha-cellulose. That however, I would agree is not proof-positive one way or another; it's just that I haven't seen it rated as a feature of alpha-cellulose.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml

Alan Goldhammer

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Re: Specialty Papers and Some - Mark Segal's Review
« Reply #2 on: March 13, 2017, 05:29:47 PM »

Mark, I was just commenting on the chemistry.  Alpha-cellulose is one of the three principal components of wood, cotton fiber and bamboo.  The length of the polymer may vary.  The other two main components of interest are hemi-cellulose and lignin.  Lignin provides a lot of the structure to wood but is the main culprit in yellowing of paper.  Pulping to make newsprint results in paper whose lignin content is significant and the main reason why it yellows quickly.  High quality paper can be derived from wood as long as the lignin is removed during the manufacture.  Bamboo 20-30% lignin by content which is one of the reasons it is so rigid.  Wood has a similar lignin content while cotton fiber is virtually all cellulose.  We don't know the processing steps of the bamboo for the Hahnemuhle paper.  It would have to be similar to that of wood pulping so that the lignin is removed.  Alpha-cellulose is biodegradable and significant work has been done to produce industrial amounts of the enzymes that degrade cellulose to glucose so that it can be fermented into industrial chemicals (including alcohol) for fuel and other purposes. 
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Mark D Segal

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Re: Specialty Papers and Some - Mark Segal's Review
« Reply #3 on: March 13, 2017, 06:30:44 PM »

Interesting Alan - thanks.

Cheers,

Mark
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml

Alan Goldhammer

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Re: Specialty Papers and Some - Mark Segal's Review
« Reply #4 on: March 14, 2017, 11:29:48 AM »

Aardenburg has some tests of Hahnemuhle Bamboo with both HP Vivera and different Epson inksets.  It's worth taking a look at these.  I looked at a couple of the Epson inkset tests and they showed a significant deterioration in the paper white patch so I wonder if there is residual lignin in the paper as this would cause yellowing.  The HP inkset seemed to be much more stable but the paper white patch didn't show as much deterioration which is curious to me. 

Alan
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MHMG

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Re: Specialty Papers and Some - Mark Segal's Review
« Reply #5 on: March 16, 2017, 10:49:16 PM »

Aardenburg has some tests of Hahnemuhle Bamboo with both HP Vivera and different Epson inksets.  It's worth taking a look at these.  I looked at a couple of the Epson inkset tests and they showed a significant deterioration in the paper white patch so I wonder if there is residual lignin in the paper as this would cause yellowing.  The HP inkset seemed to be much more stable but the paper white patch didn't show as much deterioration which is curious to me. 

Alan

Hi Allen,

Your comment caused me to go back and review some of the Bamboo light fade testing results again. My take on these test results is that the whitepoint shifting in the Aardenburg tests was not due to lignin discoloration. The light bleaching effect caused a a shift towards a cooler paper white value compared to the initially very warm white point value in this paper. These test results are an indication that Hahnemuhle has done a pretty good job of removing any lignin which if present would have promoted an increase in yellowing not less.

Any number of possible chemical reactions can account for the light bleaching of the Bamboo paper, but one industry practice is to add a variable amount of "leveling dye" to the paper pulp in order to maintain whitepoint consistency batch to batch.  Bamboo normally measures a LAB b* value very close to +4 (ISO 3655-2009 M0 defined measurement) which is noticeably more yellow than most fine art media, including OBA-free media. It might be harder to control that creamy warm-white value precisely in paper production without resorting to a dye leveling method during paper production. In any case, the Bamboo paper color bleaching in the Aardenburg light fade tests, IMHO, is not too serious, nor is it going in the direction of yellow discoloration, so I would not be too concerned.  It isn't best-in-class whitepoint stability performance, for sure, but it's also not nearly as serious a discoloration issue as we have seen in other media, for example, Epson Exhibition Fiber paper.

cheers,
Mark
http://www.aardenburg-imaging.com
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Alan Goldhammer

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Re: Specialty Papers and Some - Mark Segal's Review
« Reply #6 on: March 17, 2017, 08:55:19 AM »

Thanks for weighing in Mark.  I just looked at Ernst Dinkla's lastest data set but could not see a test for Hahnemuhle Bamboo.  I've sent him a note to see whether he has looked at it.  His spectra analysis should give an indication of whether there is any dye present.

EDIT:  Just heard back from Ernst; Bamboo paper is here in his data set:  SpectrumViz>Alpha Cellulose>Matte Medium Textured   It doesn't show much in the way of a bump one sees with OBA rich papers.
« Last Edit: March 17, 2017, 10:17:40 AM by Alan Goldhammer »
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