Posion flask Half post method

[cowseatmaize]

What year did americian bottle maker adapt the hobnail pattern on bottles to symbolizm poison?

They never did. Hobnail and other patterns like geometric have been around for a LONG time and used for all types of things that weren't poisonous.Well some things were like cosmetics but hobnail wasn't an intent to ID id as a poison, it was just pretty.