RE: Glycerol as humectant for POP Pd prints at low RH
Loris, I think this was discussed some time back in 95 or 96 amongst the PT/PD printers. I forget who brought it up, possibly Bill Laven. I tried it for some prints while living in Taos where RH can be extremely low 10% or less. It did seem to offer some relief from poor coating. After moving to Dallas and the much higher levels of humidity, I found that I gained very little or no benefit from continued use. Eric Neilsen Photography 4101 Commerce Street Suite 9 Dallas, TX 75226 http://e.neilsen.home.att.net http://ericneilsenphotography.com Skype ejprinter > -----Original Message----- > From: Sandy King [mailto:sanking@clemson.edu] > Sent: Sunday, February 25, 2007 3:41 PM > To: alt-photo-process-l@usask.ca > Subject: Re: Glycerol as humectant for POP Pd prints at low RH > > Loris, > > Congratulations on taking the time to test that premise. It is > potentially a very useful piece of information. > > Now, if more pt/pd printers would take the time to learn carbon as > you have no telling what kind of innovations we might see!! > > Sandy King > > > At 11:18 PM +0200 2/25/07, Loris Medici wrote: > >Hi all, > > > >Probably I'm not the only smart person to tried this before but > >since I haven't found a reference in the list archives, I decided to > >share: > > > >I was having hard time making cold/neutral toned POP Pd prints > >lately; the RH of my darkroom changes around 25-30% and printing w/o > >drying thoroughly (in other words: with almost wet paper) isn't a > >good choice since I'm using a relatively weak digital negative > >substrate and printing on almost-wet paper = ruining the negative > >due excess humidity. (The negative substrate I use is Ultrafine > >Crystal Clear.) I also don't prefer to use a thin (1-3 mils) > >polyester sheet between the negative and the paper because sharpness > >will suffer... (I'm printing using a 11x14" contact printing frame > >and a bank of BL tubes.) > > > >Anyway, given the above criteria, I decided to put glycerol > >(glycerine) into my coating solution. Since this compound is used as > >a humectant in both carbon printing (tissue will retain humidity > >when some glycerol is present and won't brittle) and silver-gelatine > >emulsion making, I thought it may help me in retain humidity in the > >paper -> letting me get cold/neutral tones. > > > >It works! I added a drop of glycerol per 10 drops of coating > >solution, dried the paper for 10 minutes and got a neutral print. > >Without the glycerol - keeping all other parameters constant - I > >would get a warm (brown) print. > > > >Do you think adding glycerol will affect longevity? I'm using very > >little... (0.1ml per 1ml coating solution) > > > >Regards, > >Loris.
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