Re: Gum transfer

Katharine,
I don't know much about the transparency material. Just a brand that I
picked up in a local office supply store a while back. Marketed by HP. Come
to think of it the transparency has a gelatine layer on one side for injet
printing, so perhaps it was pr-coated, subbed or somehow prepared to accept
gelatine layer. I soaked it in chlorox to soften the gelatine and the
brushed it off. Both sides seem to be working the same.
Thanks for posting the image
Marek

>From: Katharine Thayer <kthayer@pacifier.com>
>Reply-To: alt-photo-process-l@usask.ca
>To: alt-photo-process-l@usask.ca
>Subject: Re: Gum transfer
>Date: Mon, 17 Apr 2006 10:53:14 -0700
>
>Marek, you betcha I'll add your image to my site. I'm right now trying to
>replicate your results with the thick heavily pigmented coating, with some
>interesting, not 100% successful, results, but the one that's soaking now
>looks promising. I've had a very difficult time getting the very thick
>gum layer to stick through development on untreated mylar, trying to
>replicate your conditions, and have had to retreat to the scuffed mylar. I
>wonder if your transparencies are made of some other more gum-accepting
>material.
>
>Katharine
>
>
>
>On Apr 17, 2006, at 10:44 AM, Marek Matusz wrote:
>
>>There were a lot of interesting posts this weekend and I am going thorugh
>>them now. I have done a few more gum transfer experiments. Here are some
>>observations and issues.
>>
>>When exposing a gum layer through the substrate (glass, polyester, etc).
>>This is "expose through the bottom mode" heavy pigment concentration is
>>OK, coating imperfections are not that critical as the air bulles rise to
>>the top, streaks in coating are also on the top. A thin image layer that
>>adheres well to the substrate after development shows relatively few
>>imperfections and looks suprizingly good. I have not done much more on
>>that as I am waiting for a sunny weekend where I can experiment with some
>>gum on glass.
>>
>>Gum Transfer.
>>Here is how I approached it. I though it would be very difficult to
>>transfer actual developed and hardened gum image by means of softening it
>>and transferring to the paper. Instead a process similar to a single
>>carbon transfer was appealing to me. Here is what happened.
>>
>>I coated a few sheets of plyester with same emulsion (gum, lamp black,
>>ammonium dichromate) that I used in my previous experiments (expose
>>through the back). This time I exposed in a traditional way from the top.
>>I will call it the gum tissue. This should form a hardened image on top
>>of the gum layer with unexposed and soluble gum on the bottom. We know
>>what happens when you put this image in water. Everything just slides
>>off.
>>OK, I then placed the gum tissue on top of gelatine sized paper, made a
>>sanwich let it sit for a while and placed in warm water to start
>>dissoliving unexposed gum so that the tissue and the support could be
>>separated. Then just wait until the water dissolves the rest of the
>>unexposed gum revealing the image.
>>
>>Some of the difficulties. Even a very short water immersion (cold or
>>warm) of the exposed tissue to remove dichromate softens and starts
>>dissolving the gum, no usable image can be transferred.
>>
>>The tissue image needs to have decent mechanical strength for the
>>transfer. It needs to be thicker, which suggest less pigment, thicker
>>coating.
>>
>>All the air bubbles and imperfection are on top, where the image is
>>formed. There are all visible in the final image. Rollesrs and other
>>means of smooting out the coat do not work with thick layers.
>>
>>My impression is that because the dichromate is present in the transfer
>>process for about 30 minuts, before tissue is pulled away, I am getting a
>>dark reaction, or something, as I am not getting very clean highlights.
>>My exposure might be too long, or dichromate concentration too high as
>>well.
>>
>>My negatives are for Pd printing, not for carbon. Just a minor issue.
>>
>>As Sandy noted I could print in carbon, but it is such a finicky process
>>that requires a very precise time and temparature control.. I am still
>>hoping that an easy way of transfer could be found with gum, or perhaps
>>gelatine/gum mix as I am thinking now.
>>
>>I have one picture from this trials and perhaps Katharine would be so
>>kind to add it to her site.
>>
>>Marek, Houston
>>
>>
>>
>
Received on Mon Apr 17 13:25:14 2006