I have two lovely pieces of EPNS. I have identified one as Israel Sigmund Greenberg and the other as Cooper Brothers (thanks to this forum) but I would like to try and date them and find out more. I have trawled the internet for similar pieces but can’t find anything.
There is no objective method of dating these pieces. You will have to make a judgment based on style. The handles on both pieces scream “art deco” so possibly 1920 - 1960 or so. Coopers remained in business until 1983 and Greenbergs until around 1945.
Yes, you can only make a guess regarding its year of manufacturer.