Bay was one of the largest producers and made some very good designs.
They also made some rare specialty glazes that are utterly fantastic.
However, they also produced a huge amount of kitsch, tourist ware and designs of questionable aesthetic value.
In addition to this page, the site includes numerous other research items. Anglicized and Germanic pronunciations of company names Identifying West German Pottery This page includes bottoms, marks, and some information about companies and tendencies.
In the era from 1954-85, well over 100 German companies made collectible art pottery. Started by Eduard Bay in 1933; note that it's not correct that Bay stopped art pottery production in 1971; some art production continued into the 1980s, including some striking works...some not so striking; Bodo Mans; Bay was one of the top early companies with decors such as Florenz (1955), Rheims (1960), and Ravenna (1961).
Bay continued to make some excellent items through the 1960s as well as some lesser lines, but slipping demand for art pottery forced a change to kitchen items.
Although Mans continued to do some designs for Bay, documentation for who did which designs remains scarce for anything after the early 1960s.
I believe the pictures, commentary, research gallery, essays and videos make this the most extensive site designed for research on the subject.
(There are forums with more pics and such, but the forum design doesn't make research easy.) If you have questions about an item you own, I'm happy to help, but please take the time to check out the site first to make sure the information isn't already waiting.
If you do send an e-mail, include a picture of the item and the bottom.
There's not much I can do with only numbers and a description.
Note the lower case "y" used at the end of Germany.