Originally Posted by PeterB
I was not comparing both dyes, AFAIK was the MACO film made by EFKE, they used "normal" pan film (100 asa) and "doped" it with an IR sensitive dye, so that's why it needs heavier filtering that HIE resulting in very low speed.
HIE was a emulsion sepcialy designed to register IR light.
I also mentioned that I did not have problems with younger emulsion runs of MACO (in 4*5) format.
Nowadays MACO does not offer IR film by EFKE anymore, EFKE is marketing it by itself (oa through Freestyle),