What are you using for your temporary support?
Thanks for the reply...I always thought the gelatin bonded to Yupo too strongly, and it was only appropriate for tissue or final support.
Do you treat it in any way to get the image to transfer cleanly to your final support?
I am also reusing the yupo sheets. That's why I use the 160 and 200gr sheets. First I used a thinner one that comes off somewhat easier in the warm water but is much more difficult to handle before that. For color prints I use the 200gr. Registration holes can be punched in directly.
Kees...I appreciate your detailed response regarding how you make your tissues. For those of us in the US, I believe the 200 gsm weight of Yupo is equivalent to the 74 lb. Yupo.
I think there was a misunderstanding at the root of my question, however.
You said you do double-transfer for your color work. I was asking about the temporary support...the material you transfer each color layer to before you transfer the whole assembly to the final print paper.
Sorry about the confusion...
This changed dramaticly when I tried the albumen method. Tod's video shows how to do it and a write up of his method can be found at the sizing appendix of Dick Sullivan's Carbon Printing Manual. It really makes transfer very very easy! A description of the same method by Gary Baker can be found in the Yahoo Carbon list files section.
But it reintroduces dichromates again..., although in very low concentration. So next I will try to harden it with DAS (from Di-Azido-Stilbene, the chemical industries nickname for our beloved powder) as suggested earlier by Charles. With an albumen coating you can use almost any transparant substrate. For the moment I prefer transparant polycarbonate (0,25mm). It is very dimensionally stable and stays perfectly flat.
By the way: for the sake of continuity I did some reseach for other diazidostilbene suppliers worldwide. I found a Shanghai based chemical company that sells 1 kg for $350 - not a bad price! It's double the price from the current Secant sale, but they seem to have it in generous quantities!
Just FYI, Yupo is very similar to Ultrastable. These supports are very similar to the support used for coating Ciba/Ilfochrome color material.
The base material used for coating Ciba/Ilfochrome was Melinex, manufactured by ICI , is Polyester . Yupo is made of polypropylene and is similar to the Kimdura "synthetic, water proof paper" that was used as a base for coating the UltraStale pigment films.
Polyproplyene should not be used as the final support for carbon transfer prints. Testing has shown it exhibits serious long-term adhesion and cohesion failures.
The white UltraStable base had a gelatin top coat over an in-line gel subbing layer. A receiving top coat is necessary for the long term stability of any prints made onto polyester.
A rule of thumb: if you can transfer the image from a temporary support sheet (yupo, polyester, etc). it should not be used as a final support. You can also test for this by using scotch tape to peel off the processed gelatin image.
I did NOT say they were identical. I said they were similar, ie, they are plastic like, subbed white reflective materials. They all resist processing solutions and all will accept gelatin coatings provided the subbing is correct.
Melinex is a transparent material in most all incarnations I have seen, and the version used must be chosen with the application in mind as it does not always work out right, just as Polypropylene is not always right. Since one of the people here uses Yupo, it must be that he has found a way to work with it in carbon printing, but IDK. His post suggests that it works just fine.
Sorry about the miscommunication. To clarify:
Melinex 990, an opaque white polyester, was used as the base for Ciba/Ilfochrome (7 mil) and some UltraStable (9 mil) prints. The clear polyester did contain a small amount of transparent white pigment (TiO2) but was extruded in such a way that "soap like bubbles" were formed that reflected, rather than transmitted, visible light thus causing the clear polyester sheet to appear "white".
Another feature of the 990 was the "Bexford Sub' - a thin layer of gelatin applied "in-line" (as the polyester was being made) at ICI's Bexford plant. This subbing layer was designed to receive and anchor subsequent coated layers to the polyester support.
As you know, gelatin stress increases with film thickness, and high relief carbon prints are particularly susceptible to cracking and base lift-off. After the Bexford plant blew up in the late 1990's the in-line gel sub was no longer available, other subbing techniques (corona discharge, chemical etch, off-line gel layer, etc) were tested but all showed signs of adhesion failure and UltraStable discontinued offering a White base. The adhesion performance of these new sub subbing layers, however, were suitable for Ilforchrome