Re: possible answer to archivalness comparison between carbon gum andpt/pd
I have looked up the last pages of "A New History of Photography" (M Frizot) and there is no mention about carbon print. Instead, there is a beautiful example of cracking (both 2x and 20x) occurring in an albumen print.
But if I look to my two original albument prints and I am not able to see any crack...
Quoting Frizot about platinum prints: "these very stable images have, however, the disavantage of attacking paper with which they come in contact, owing to the acidity of the process".
I don't know if this is ever true. In my opinion, an extended washing, especially if performed with hard tap water, is able to neutralize whatever acid pretreatment.