Upvote:10
Looking up colour standards, it seems plausible that this green was defined in the RAL classic colour system, which is widely used in Europe and was created in the 1920s. My colour vision is not very good, but it looks to me like a slightly faded version of RAL 6000, "Patina Green".
Upvote:15
β¦ the green color that the wonderful Ce 6/8 II "Crocodile" locomotives wore while driving across the alps during the 1920s β¦
Well since you specifically ask about the 1920s, it appears that the answer is "none". According to all sources I could find, specifically https://www.stummiforum.de/t19973f20-SBB-Krokodil-Braun-oder-gr-n.html or https://lokifahrer.ch/Lokomotiven/Loks-SBB/Ce_6-8-II/SBB-Ce_6-8-II.htm, the crocodiles wore brown at that time. The green livery didn't come until the 1930s and even then it took a long time to convert the whole fleet.
If you're really curious and need a definitive answer, I suppose you'll find it in the dossier KDII_DIV_SBB66_0133 "Anstrich der elektrischen Lokomotiven" ("coating of the electric locomotives") which is available to order from the SBB archive.
Upvote:16
@[email protected] says NCS* 8010-B90G, which is closest (but not exact) to RAL 6009. The German wikipedia page for the Ae 6/6 calls the color "tannengrΓΌn", which is the name of RAL 6009. The source seems to be official documents hosted on the SwissRailModeling Yahoo group, which as far as I know is lost to time.
The image you linked is quite weathered, this one shows newer paint.