[Alt-photo] Re: Mechanism for Platinum Enlargements

[Peter Friedrichsen]

The ferric oxalate light sensitivity is still very good up to about 
520nm (throughout the blue light range) so maybe the Durst Azo unit, 
which I see uses quartz halogen, could do the job. Perhaps you could 
find one to test.

Peter Friedrichsen


At 12:40 PM 05/11/2013, you wrote:
>Hi All,
>
>I may have asking something along these lines a long while back but I'm
>unsure. There also may have been a bit of conversations around this on-list
>in the past. Anyway, I've always been fascinated with the old methods for
>making Platinum enlargements and I'm curious if anyone knows any of the
>numbers (exposure times) or knows of anyone who's working (albeit slowly)
>with anything like this now.
>
>Despite common belief, making platinum prints through an enlarger is indeed
>possible and there is a long history of this. As a quick recap, the most
>common method was through the use of a solar enlarger attached to a
>heliostat. The solar enlarger was essentially the same as a modern
>enlarger, most commonly using condenser lenses but there is documentation
>discussing diffusion solar enlargers as well, and lenses that were good at
>passing UV light. The heliostat was a mechanism that allowed the enlarger
>to track the movement of the sun subsequently keeping the light source
>centered and focused throughout the printing.
>
>Much later Durst made a UV enlarger for Azo and supposedly had one in
>development for platinum printing but it never made it into production.
>
>Anyway, I've heard whisperings of people who's made platinum enlargements
>essentially in conventional enlargers after replacing the lens with an
>older lens that'll pass uv light (modern lenses tend to block uv) but I
>can't really find any documentation of this. What I've heard is that the
>super powered lamps as used in the Durst UV enlarger (5kw and requiring
>serious cooling) are not actually necessary if you're ok with loooong
>exposure times (into hours). The Durst was supposedly designed to make
>these exposures both possible and relatively quick. I personally wouldn't
>care if the exposure times were very long if this is something that could
>actually be achieved.
>
>Does anyone have any information/experience with this? Any idea of how long
>exposure times would actually be if using a uv bulb or mercury bulb in a
>diffusion or condenser enlarger?
>
>Lets try to keep this on topic. This isn't intended as an opening for
>recommendations to contact print or make enlarged negatives. This topic
>isn't concerned with any alternatives. We're all aware that platinum prints
>are conventionally made using contact printing. We also know about making
>enlarged negs. No need to touch on any of that here. This is about the
>feasibility, practicality, and possibility of making a platinum enlargement
>via an enlarger set up to utilize uv light. We're also not tied to
>attempting to attain short exposure times here. Long is fine. I'm
>interested in tapping into the creative thinking of those on-list so lets
>try to limit the "thats impossible" talk. We already know that platinum
>enlargements are possible. Thoughts?
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