[alt-photo] Re: Dichromated Gelatin Formula

[etienne garbaux]

I wrote:

 > I seem to recall that one or more of the other old salts (Wall?  Clerc?)
 > also gave Woodburytype formulas, but do not recall which one(s).

I think the other reference I was remembering was in Crawford's 
Keepers of Light.  He gives a nice historical description, but no 
workable process information.

The motherlode for potential Woodburytypists is Leon Vidal's Traite 
Pratique de Photoglyptie (Gauthier-Villars, 1881).  ("Photoglyptie" 
is the French name for the process.)  Eder translated it into German 
as Die Photoglyptie oder der Woodburydruck (Knapp, 1897).  I have 
both around here somewhere, but am not finding them at the moment.

I believe that Woodbury also had some English patents on the process 
that might be worth looking at.  They would probably date to the 
early 1860s through the mid-1870s.  (If you find the patents, please 
post links.)

Now the bad news:  The magic of the process, and what gave 
Woodburytypes their ethereal look, was the immense pressure used to 
make the lead molds.  Because of that, no modern casting process has 
even the slightest chance of making images that look like 
Woodburytypes.  (Woodburytypes have relief, like a carbon print.  The 
shadows are very glossy and well-defined, while the highlights are 
subdued and matte.  Some of the fine details in the highlights are 
softened, which gives an effect not unlike a good soft-focus portrait 
lens.  A very handsome combination, IMO.)  So, if your goal is to 
achieve the look of a Woodburytype, you will need to find a big 
honking hydraulic press you can use.  You'll need over 500 kg per 
square cm, so even modest sized prints require a press capable of 
over 100,000 kg of force (over 100 American tons) -- like this one: 
<http://www.phoenixhydraulic.com/Presses/HFrameShopPresses/150200TonHFramePresses/tabid/197/Default.aspx>. 
(That is a general shop press, so it opens way, way more than you 
would need -- but that's the kind of press you would be most likely 
to find available to use.  Lots of small and mid-sized industrial 
companies have them for working with metal.)

Best regards,

etienne