[alt-photo] Re: Alternative sensitiser

[Peter Friderichsen]

Kees,

To mildly hydrolyse the gelatin, you can either acidify, or alkalize 
it, then heat it for a limited time, or use an enzyme like that from 
fresh pineapple. They all seem to result in different surface 
properties of the gelatin which now is liquid at room temperature and 
whose prints produced from such, can be developed at room 
temperature.  M. Carey Lea first made something like this which he 
called meta-gelatine.

You can keep this for some time at room temperature if you add the 
right preservative, but like any gelatin in solution, it will slowly 
auto-hydrolyse (much slower if kept cold), and the result will be 
weak prints. At room temperature, I find it works well for about 6 
weeks. Gum arabic as you know seems to last much longer if preserved.


Peter Friedrichsen

At 03:24 PM 04/18/2010, you wrote:

>Hi Peter,
>
> > I use this type of gelatin as I would gum but usually I use a 20% 
> wt in solution versus the traditional 30-40% for gum.
>
>And how did you modify or hydrolize the gelatin to keep it liquid? 
>Do you use warm water to develop the gelatin print?
>
> > I did come across the Ulano name as well under Bernard Ulano of 
> Diagravure film -not sure if this is related to the Ulano that you 
> mention. Re patents, yes many do not work. I have found this out on 
> numerous occasions.
>
>
>Bernard Ulano was the one who filed the patent with the combination 
>of a simple and complex ferric salt. Diagravure was, as far as I 
>could find a subdivision of Ulano. About Bernard I could not find 
>anything photo related. The patent is here:
>
>http://www.google.nl/patents?id=ii4CAAAAEBAJ&zoom=4&dq=RELIEF%20%20IMAGE%20PROCESS%20UTILIZING%20A%20SIMPLE&pg=PA74#v=onepage&q&f=false
>It worked, but was very unpractical because of the immediate 
>hardening if the ferric mix was not consistent. The sensitivity gain 
>was nonexistent or very low. So I decided to stay with the Ferric 
>Ammonium salt.
>
>When I mailed about this with Halvor some time ago he found another 
>patent for the Diagravure Film Mnf. Corp. filed by Kosar (!) 
>himself. So they probably knew each other.
>
>
>-k
>
>
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