Yes, we are coating on polyester and are working with a register system
>>C-exposure, transfer to the plastic with YM-layers etc.
>>This means - very often - a rather thick layer. After drying we transfer to
> ^^^^^^^^^^^^^^
>Especially if it is a dark, low-key image.
>
>>a STS (paper). Dry and peel off the plastic. Then transfer to final paper
>>in warm water. And the thrownaway STS is yellow where the thick and dark
>>parts from the image were. After drying we clear in pot meta bisulf, dry
>
>humm... for a moment I thought that your yellow stain came from the yellow
>pigment layer, but it is *away* (as it should for technical reasons) from
>the STS... Your procedure is very different. You are developing one layer
>(Y) and after drying it leaves a solid yellow (pigment) image on plastic.
>Then you are transferring the next exposed color (M) right on top of the
>dry yellow and since everything is on stable support and pin registered (I
>presume) everything falls into place and you develop your magenta right on
>top of the yellow. Ditto for cyan. When all is done you transfer this
>tricolor image onto the STS which somehow ends up with a yellow
>"dichromate" stain...
Yes, that is the way we do
>With the "traditional" method, as I have arbitrarily defined it, each
>exposed pigment layer is transferred from a *PAPER* base and developed on
>three *separate* plastics. These images, after drying, are transferred one
>at a time onto the STS which in the end will keep nothing (pigment or
>dichromate stain) before leaving the image alone on the final transfer
>paper. It is as if sowehow our (Sandy and mine) method allowed more of the
>soluble dichromate to dissolve in the extra baths of cold water. I'll have
>to think about this one for a while...
When we did the traditional way (*the 47 steps method* ), in the second
half of the 80's, we cleared each plastic TS as we had noticed a difference
in clarity in the colors. Have you tried this? When we skipped the bad
Hanfstaengl material and started to coat our own tissues we used polyester
and not paper from the very start. During some years we exposed through the
plastic and transferred one at a time onto the STS. But, as we wanted to
keep our hair, and get rid of the tedious register problems (creative
misspass we called it) with the STS paper changing size all the time, we
developed a register system which works very well for our working
conditions. We expose on the emulsion side and transfer/develop each layer
on top of each other. The final print looks exactly like one made the
*traditional* way - but without misspass. This method has also shortened
the printing time *some days* :>))
>Not that it would make that much difference but how much soaking time in
>cold water do you use before you transfer each exposed tissues onto the
>first Temporary plastic support for developing?
Max one minute in cold water and the transfer water gets very yellow from
the dichromate:<(
Regards, Hans & Chia