"Safe" Replacement for Formaldehyde Pre-Hardener?
I am working with some greatly expired (1970's) color negative aerial film, and have been told by the helpful folks at Kodak that the film requires a formaldehyde-based pre-hardener, as well as a formaldehyde-based dye stabilizer during the developing process, with these chemicals being discontinued 10-15 years ago due to toxicity concerns. :blink:
I did a series of clip tests of the film using black-and-white chemistry, and found that at too warm of temperatures, the emulsion became so soft that it bubbled and sogged off of the film base entirely. :blink: I was able to keep it all together by doing a "cold" develop (just a touch above room temperature) with very minimal agitation, but I still experienced some reticulation in the end. :( However, all told, I found the film to produce an image which was usable enough for my purposes.
The questions I have going forward:
* Is there a reasonable (less toxic) substitute available as a formaldehyde-free pre-hardener? Note that I'm not interested in a formula to re-create Kodak's discontinued chemistry.. I'm looking for something that is safer, even if it is less effective. ;)
* Should a hardening fixer be used with film of this type, or was it intended that all of the hardening be done prior to the developer?
* In the absence of a suitable pre-hardener, are there any other chemicals or process changes which would minimize the swelling of the emulsion or the chances of reticulation?
Thanks for the help. :cool: