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Author Topic: Outgas problem........and Prints with waves/ripples  (Read 8817 times)
dchew
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« Reply #20 on: October 09, 2010, 06:32:37 AM »
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I guess the same hot plate underneath and a moving air jet in front would have a similar effect, glycerol then condensating on the cool parts of the studio :-)

Yes, I think the combination is the key.  There are two mass transfer effects that need to be accelerated:  The chemical concentration gradient in the paper, and the boundary layer between the paper and the air.  Placing the print in a closed dry-mount press gets things moving but they have no where to go.  Paper-on-top wicks but seems to me it would quickly reach equilibrium without addressing that new boundary layer. 

Heating the paper ought to speed up mass transfer within the sheet, i.e. increasing the concentration right at the surface.  Then hot-moving turbulent air at the surface improves the gradient at the boundary layer.

Dave
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Alan Goldhammer
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« Reply #21 on: October 09, 2010, 07:02:27 AM »
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Yes, I think the combination is the key.  There are two mass transfer effects that need to be accelerated:  The chemical concentration gradient in the paper, and the boundary layer between the paper and the air.  Placing the print in a closed dry-mount press gets things moving but they have no where to go.  Paper-on-top wicks but seems to me it would quickly reach equilibrium without addressing that new boundary layer. 

Heating the paper ought to speed up mass transfer within the sheet, i.e. increasing the concentration right at the surface.  Then hot-moving turbulent air at the surface improves the gradient at the boundary layer.

Dave
Unfortunately, in the case of glycerol, you can't raise the heat enough to be significant because of the low vapor pressure.  It only becomes meaningful as you approach 100 C which would damage the image in the case of glossy papers (and probably matte as well).  You still cannot defeat the laws of physical chemistry in terms of the differential concentrations of glycerol/water.  It is the elimination of the excess water that is key since it acts as a carrier for the glycerol, causing the outgassing (which is probably a misnomer since water vapor is a gas as well and what we are concerned with is the glycerol vapor).
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Ernst Dinkla
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« Reply #22 on: October 11, 2010, 04:24:32 AM »
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  In addition, one would obviously expect matte and RC papers to behave quite differently (it would be interesting to find out from others whether rag based glossy papers exhibit the same type of gassing phenomena as the RC papers do).  I'll see if I can track down some vapor pressure data and see if a sample calculation can be done.

So far fogged glass reports mention RC papers and no other paper types. Which also raises the question why one should use RC paper if the print will be framed. There are matte, satin and glossy RC paper qualities but I guess the last are mostly used and are not ideal for framing considering the reflectance.


met vriendelijke groeten, Ernst Dinkla

spectral plots of +100 inkjet papers:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
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Alan Goldhammer
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« Reply #23 on: October 11, 2010, 07:06:37 AM »
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So far fogged glass reports mention RC papers and no other paper types. Which also raises the question why one should use RC paper if the print will be framed. There are matte, satin and glossy RC paper qualities but I guess the last are mostly used and are not ideal for framing considering the reflectance.
Yes, that is what I've seen reports of as well.  I did some more research into the topic over the weekend and the data that I have found confirms what I believe is going on.  At the temperatures people are employing to dry prints, what is coming off is water vapor.  If one looks at the vapor pressure data for glycerol/water mixtures, 99.96% of the vapor at 106 C is water so one is not seeing much if any glycerol coming off the print.  The other unknown is what other organics Epson uses in the ink mixture (the 5-10% of the ink).  Some have mentioned noticing an odor when they use the hair dryer method.  Pure glycerol is odorless but the other organics could have an odor (many ketones used as solvents have a slight sweet smell).  The observed fogging could be a result of these volatile organics that may still be present if the print is not adequately dried.  The key thing is to get rid of the water so that there won't be any vaporization when the print is framed since this could carry trace amounts of either glycerol or something else to the gas phase and cause the fogging.  Clearly one also needs to avoid extremes in temperature (including direct exposure to sunlight or other high intensity light source that can elevate the temperature) as this would alter the equilibrium causing gassing in a semi-sealed environment of a picture frame.

I guess the good experiment to conduct here is hinted at by Ernst and that would be to take prints on RC and Rag papers by the same manufacturer with a gloss like finish, frame them and see if there is discernible gassing.  I can only report my own findings of long term display on Ilford Gold Fiber Silk that show no outgassing at all after 12 months of display at my office.  13x19 prints framed under plexi and mounted on a wall illuminated by normal office lighting are fine.  I also have some prints on Museo Silver Rag and Portfolio Rag on the same wall.  As I noted earlier, I took no special precautions regarding drying other than to put a sheet of archival paper over the print and prints were mounted on archival foam board with a 4 ply overmat after a minimum of two days drying time.
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Lisa Nikodym
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« Reply #24 on: October 17, 2010, 05:29:47 PM »
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I used to have similar problems with outgassing in clip frames using Epson glossy & semi-gloss papers, including the Epson luster.  I did experiments with several other papers, and found that those Epsons were the worst for outgassing.  Matte papers don't have that problem at all.  For semi-gloss, I ended up using Ilford Galerie papers, which had far less outgassing than the Epson papers, not enough to be a problem.   (I currrently use Ilford Gold Fibre Silk, and before that the Ilford Smooth Gloss - minimal outgassing.)

I put plain copier paper on top of each print for about a week just in case...

Lisa
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Waltere
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« Reply #25 on: November 09, 2010, 08:26:45 PM »
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Ok, I got my 3880 two weeks ago, printed 20 13 X 19's last week, and just finished framing them! I printed on Moab Entrada Bright 300, and let them "dry" for 2 days, then interleaved them with 2-ply rag for 3 days...I am hanging them on Thursday, so I will be keeping an eye on the outgassing issue!
What is the dry-mounting procedure for pigment prints, what tissue & temperature & time? I still have a stock of MT-5 that I use for my darkroom prints & and I use it around 220 degrees...also, is a sheet of 2-ply okay between the pigment print and the press?

Waltere
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