[Alt-photo] Re: DAS

[Loris Medici]

Thanks Charles,

I recently visited a large exhibition of Nickolas Muray's photos,
there were many (gorgeous!) color carbro prints there, and even if
they had at least 3 layers, the slight relief wasn't as strong as (not
even near to) many other high relief single layer monochrome carbons
I've seen before. Sandy King's prints for instance, I know Vaughn
Hutchins makes carbons with considerable relief too. And to my
knowing, both make relatively lightly pigmented / thick tissues...

I'm a little bit confused right now? OTOH, thinking over, your remark
would be for dry tissue as in the case with DAS; with dichromates, one
would be exposing a wet / swelled tissue, therefore the depth of
hardening of at time of the exposure may be bigger than the 1mil
figure you mentioned...

Regards,
Loris.

(Irrelevant note / question about Nick Muray's prints: Some of
Nickolas Muray's color carbro prints were showing an interesting
halftone pattern. AFAIK, he was using a special camera with a prism
for making 3 negatives in one shot and the prints I've seen were
definitely not reproductions but the real stuff; signed w/ visible
relief... Why halftone screen? Any thoughts?)



2013/4/18 Charles Berger <fotocmb at gmail.com>:
> The light restraining effect of dichromate (or DAS) in a  gelatin emulsion
> keeps the light from penetrating very deeply into the film regardless of
> excess coated film thickness.  Even a clear (no pigment) film with a weak
> (say 1%) sensitizer will have far less than a 1 mil depth of hardening.
> More sensitizer (or more pigment) will further limit hardening depth .
>
> The apparent "relief"  of carbon tissue has more to do with local
> variations in the surface tensions of the processed and dried film layer
> than with infinitesimally slight physical differences in d-min and d-max
> areas.
>
> Charles
>
>
> On Thu, Apr 18, 2013 at 12:44 AM, Kees Brandenburg
> <workshops at polychrome.nl>wrote:
>
>> Hi Loris,
>>
>> Once you get used to presensitized carbon tissue with double transfer you
>> will see the huge advantages this gives. You can also build up relief by
>> printing in layers. You don't need to work with color separations, printing
>> two layers of black/medium black on top of each other works great and the
>> result can be more powerful than a single layer carbon print.
>>
>> -k
>>
>>
>>
>>
>> On 18 apr. 2013, at 09:03, Loris Medici <mail at loris.medici.name> wrote:
>>
>> > I can understand the need for thin tissue for color work, but (with
>> > the exception of gum or gumovers) I only print monochrome, and what
>> > draws me to carbon is the relief. I'm quite happy with what I can get
>> > from pop pd and/or gold toned vdb/argyrotype...
>>
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