[Alt-photo] Re: Mechanism for Platinum Enlargements

[Marek Matusz]

Maybe I could try a bank of uv led's as a diffused light source. I tried a house led light to print cyanotype once. It was a long exposure but I got an image  
Marek

Sent from my iPhone

> On Nov 7, 2013, at 6:41 PM, "Francesco Fragomeni" <fdfragomeni at gmail.com> wrote:
> 
> Don and Peter,
> 
> Thanks for chiming in! Sorry for the delay in response. The work week has
> been insane.  Anyway, the mirror idea sounds interesting. As does the idea
> about trying to find one of the Durst units. From what I understand the Azo
> enlarger was really just a Durst enlarger with the high powered 5kw head. I
> wonder how difficult it would be to get a hold of one of those heads. I'm
> also curious what the power requirement would be. I live in NYC so running
> a dedicated power source isn't really not a possibility.
> 
> I've also seen mentioned a number of times that people have had success
> enlarging on Azo (and feasibly pt/pl) using a regular color head. I'm
> assuming that their making use of a blue setting. It's strange, I've seen
> this mentioned but no one really seems to describe it in detail at all. I
> also have an actinic cold light back in phoenix which could yield a similar
> result. I'm unsure when Id be back there an able to test this.
> 
> Another question that comes up is the difference in negatives that would be
> required. I'm used to working with a denser and contrastier neg for contact
> printing pt/pl. I wonder how this would change when projection becomes a
> part of the equation. Ideas here?
> 
> My darkroom in NYC is small and set up for contact printing so I have no
> enlarger. Maybe I'll have that cold light shipped out and rig an enlarger
> out of a spare view camera to see what I can get to work.
> 
> Any more thoughts or ideas on this topic?
> 
> 
> On Tue, Nov 5, 2013 at 11:02 PM, Peter Friedrichsen <
> pfriedrichsen at sympatico.ca> wrote:
> 
>> 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?
>>> _______________________________________________
>>> Alt-photo-process-list | altphotolist.org
>> 
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