RE: Bottem of the Van Dyke Barrel
Michael, In his first 1939 wartime speech Winston Churchill remarked about Germany's war on Soviet Russia, "It is a riddle wrapped in mystery inside an enigma ..." Such is my experience with VDB solution. When I mix a batch I date the label and dump it after a year, as it mysteriously changes in appearance and printing qualities. I've never observed that VDB gains speed as it becomes older - just the opposite, nor traditional cyanotype. However it is my anecdotal observation that cyanotype is much slower to change than VDB solution. Perhaps there is someone on the list that can share some hardcore sensitometeric analysis of aging VDB solution but I would advise mixing a fresh batch and calibrating with that. My 2 cents, Don Bryant -----Original Message----- From: Michael Koch-Schulte [mailto:mkochsch@shaw.ca] Sent: Friday, March 02, 2007 7:57 PM To: alt-photo-process-l@sask.usask.ca Subject: Bottem of the Van Dyke Barrel At first I thought it was my printer and inks. Then I thought it was a change in my workflow somewhere. Maybe it was my coating method. No. It may seem like a silly question but is it just normal that emulsions like VDB, Cyanotype and others start to gain speed over time? I don't do a lot of VDB but recently I was testing some of my remaining solution from a batch from last year and it seems to be printing three or four times faster than it did initially. ~m
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