Re: Gum transfer

Marek,

The principle is that you leave the sandwich under pressure for a
half hour or so for the gum and gelatin to stick together. Then hang
to dry. If your gum image is on plastic you must use a fiber photo
paper, otherwise the sandwich will never dry.

Sandy

>Sandy,
>I assume this is for the developed image on plasitc to be
>transferred to another support. Is a fiber based photo paper the way
>to go? Should the drying be done under pressure? I guess I have to
>read some literature on carbon double transfer. It always seemd so
>complicated I aways skipped that chapter.
>Marek
>
>>From: Sandy King <sanking@CLEMSON.EDU>
>>Reply-To: alt-photo-process-l@usask.ca
>>To: alt-photo-process-l@usask.ca
>>Subject: Re: Gum transfer
>>Date: Mon, 17 Apr 2006 14:11:15 -0400
>>
>>Marek,
>>
>>Try the following and see what happens.
>>
>>Take a piece of photographic paper and fix it out and allow to dry.
>>After it dries, soak it again in a alkaline solution of very hot
>>water for 15 minutes or so, then rinses briefly in warm fresh water.
>>
>>Squeegee the gum print on plastic to the emulsion side of the photo
>>paper, leave under pressure for thirty minutes or so, then allow to
>>dry. Drying may take several hours. The image should either stay on
>>the plastic or transfer to the paper, or half and half which would
>>be the worst case scenario. This is the protocol for double
>>transfer carbon. May not work, but should be worth a try.
>>
>>Sandy
>>
>>
>>
>>>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 14:55:30 2006