Subbing silicon coated mylar for carbon tissue

[koraks]

This is a shameless cross post from the same question on Photrio: https://www.photrio.com/forum/threads/subbing-siliconized-bo-pet-mylar-estar-film-for-gelatin-adhesion.193350/unread
My apologies for any who come across this twice, but my estimate is that there's going to be just a handful of people across both forums who are likely to have good suggestions on this (bad ones are nonetheless also welcome - seriously, don't hold back).

To summarize from the thread linked above: I've got this roll of silicon coated (both sides) Mylar (officially BoPET, which is basically Melinex or the base material of Estar as well) which I'd like to use as temporary support for carbon tissue. Since it's phenomenally water-repellant, I'm looking for a way to sub it so that carbon tissue will stick to it.

I tried dilute gum arabic, but anything water-based just beads on the surface. Dragging a sheet through a tray with subbing solution doesn't work.

Has anyone dealt with this before?

PS: yes, I know fixed out silver gelatin paper works fine as a temporary support, as do a variety of other materials, and your suggestions are certainly welcome, but the gist of this question is how I can use this particular material in this particular application.

[Drew Wiley]

Silicone is a one-way street. Nothing is meant to stick to it; and it's not meant to be removed.

[domaz]

It sounds like great material to help coating your carbon tissue... See Calvin's video (https://www.youtube.com/watch?v=u1JkwfPQDA0) where he uses RainX on his table while making tissue. But using it for temporary support why exactly? There are a lot of other materials that work great for temporary support. Like Yupo or Grafix Dura-Lar. The latter not needing any prep whatsoever in my experience- just transfers right to it and you can use it for double transfers as well.

[koraks]

Drew, thanks, I was afraid of that.

Domaz - because I've got it, that's why. I know about yupo and quite frankly I never understood the big deal with a relatively expensive material in this application. These days we can actually get it here in Europe; when I first tried my hand at carbon it was unobtainium here. And yes, I know it can be reused, but that doesn't suit my workflow and taste. I'd rather trim to size for a couple of reasons, so a cheap and plentiful support for tissue would be nicer than a premium material.
I generally use expired RA4 paper which works a treat, RC as well. I might look into the dura-lar if I can't find anything else. Btw, this is meant primarily as a tissue support, but it's nice if a print actually transfers to it as well in case I want to proceed to double transfers.

Thanks both for chiming in; any additional thoughts are certainly welcome.

[domaz]

Can you get something like PET 5.5 mil Eco solvent film in Europe? I've heard it's a good cheap option for tissue. Also you can try to pick up X-Ray film on Ebay, it doesn't matter if it's expired or gone bad so you may be able to get it cheaper than the normal price. I use 14x17 X-Ray film as a tissue support and it works well. I do briefly fix it out and rinse it though I've heard you can just skip the fixing out step too and use it as-is.

[koraks]

I've got x-ray here, probably even some blue stuff I wouldn't use for anything else, but I've only got 8x10 and that's too small for printing 8x10 negatives. Moreover I'd prefer something a little less sturdy than x-ray film; I find it nicer in the development bath if the temporary support peels off instead of slides off. Less risk of an edge of the support scraping across the print surface.
And yes, fixing out is optional, although I suppose some dyes in hoger end films like Ektascan BRA might stain the final support.
Thanks for the suggestion on the 5.5mil stuff; I'll look into that. There must be many types of film material that work; the question is how to identify them based on specifications.