All things Chiba and Dichromate alternatives.

[nmp]

From the brief experience I had with hide glue and CHIBA process, it didn't need any O2 barrier. The hardening happened just fine. Habib Saidane in his myriad combinations of materials/process never uses one. So it must not be critical requirement. In theory, O2 is a quencher in a free radical reaction hence the caution in the original thesis paper.

:Niranjan.

 

[imgprojts]

Is there much evidence of CO2 bubbles from the citrate decarboxylation? I'm reminded of DAS forming nitrogen during carbon transfer.

When I spray or dunk the exposed tissue to H2O2 0.3% I do see tiny bubbles form on top of the emulsion. It doesn't seem to cause big visible spots on an image though. However, I also never used an agar agar cover.

 

[koraks]

From the brief experience I had with hide glue and CHIBA process, it didn't need any O2 barrier. The hardening happened just fine. Habib Saidane in his myriad combinations of materials/process never uses one. So it must not be critical requirement. In theory, O2 is a quencher in a free radical reaction hence the caution in the original thesis paper.

:Niranjan.

It might be related to the fact that Chiba as I recall explored alternatives for a transfer process; the direct pigment processes don't involve a transfer. I might not remember that bit correctly though.