Over the course of past 6 months I have been developing methods for dating crown caps, first just those from Serbia, and later from ex-YU countries (Croatia, Slovenia, Bosnia, Montenegro, and N. Macedonia). Initially I was using Google search for news and history articles on internet mentioning brands and breweries and news of their anniversaries, acquisitions, and new beers. While doing that I was discovering official web sites and YouTube channels of breweries occasionally with timelines and mentiones of those events, and dated videos introducing new products. Later I added factory signs (FS) as a method of establishing period or more or less accurate years of issue for certain caps.
Beer labels on bottles and cans also proved to be a valuable source of dating information, where I was matching graphical design on dated labels with those on caps. Unfortunately, more than 80% of bottle labels do not have the date ("best use by") since collectors have unused labels, or incomplete labels (just the front label, while the date was on the back or neck label of the bottle). Also, labels prior to 1990's rarely had the year, but just the day and month of the production, since in those days production technology resulted in beers with a much shorter shelf life (few weeks compared to 6 months now).
Valuable source are collections of beer cans and unopened bottles that have well organized online presentations, with the year of production for each item in collection.
Recently I discovered a website for rating beers, with dated comments that point to the year of issue (earliest rating), and the range of years beer existed (indicated by the latest rating).
Auxiliary methods were analyzing the evolution of the logo design, appearance / disappearance / change of words and graphical elements, as well as mentioned anniversaries. Personal memories are the least reliable source, but sometimes are tied to events like birthdays or school year that can be precisely pinned in time, when contemporaries can shed light on years of issue or range of years a beer (and crown cap) existed.
As a quick recapitulation,
here are those 10 methods for dating crown caps, and example links:
1. Internet articles and
dated photos (Google)
2. YouTube channels of breweries
and their web sites
3. Bottle label catalog https://colnect.com/en/drink_labels/countries
4. Factory signs http://crowncaps.info/signs
5. Beer cans catalog https://m.facebook.com/profile.php?id=100009586476310&v=photos
6. Unopened bottles catalog www.facebook.com/Gospodjinci.Serbia/photos
7. Website for rating beers
https://www.ratebeer.com/breweries/
8. Establishing anniversaries and major events in the brewery history
9. Evolution of the logo
design (example http://www.ultrahome.in.rs/crowncaps/chronology/karlovacko.html)
10. Interviewing contemporaries
Mihailo Aliæ, researcher and collector, Belgrade, November 2021.
http://www.ultrahome.in.rs/crowncaps
http://crowncaps.info/collections/4946