I bought a pack of 4x6 AZO that expired in 1920 on ebay a while ago. I actually just wanted the box, but I thought I should try the paper out. I developed for 1 minute in Ansco 130. The first sheets came out with pretty heavy fog. I added some benzotriazole and it didn't help much. I then tried overexposing it and giving it a much shorter developement time 20 sec + 5 sec drain and a water rinse. The image mainly forms in the rinse and the fog is almost not there. The images look quite good actually. Good enough that I may make some 4x6 negatives to print on it. Any ideas on how this might work in Amidol (I didn't want to mix some up for this test)? Does benzotriazole work well in Amidol? Has anyone found any older Azo that still works? I missed out on a few packs that I think were from 1917?