The Owens-Illinois Glass Company formed in 1929 and quickly grew to own most of the glass manufacturing market. You can recognize their bottles pretty easy by the trademark image on the bottom.
Between 1929 and 1954, they used a very distinctive “diamond IO mark,” trademark that looked like the letter ‘I’ within an oval superimposed on an elongated diamond.
Then in 1954, they removed the elongated diamond and just used the letter ‘I’ within the oval.
It’s a good thing they included these trademarks, because we can use them to figure out roughly when our whiskey was made. Here’s how to decipher the code:
- If you see the trademark with the diamond, your bottle was produced in the 1930s, 1940s, or 1950s.
- If the bottle says “Duraglass” in raised letters, you can rule out the 1930s because that didn’t come along until 1940.
- If the diamond isn’t there and you just see the oval and the I, then your bottle was produced after 1954.
Now that we know the manufacturer and the general time-frame, we can use the raised numbers on the bottom to get the exact year when the glass bottle was manufactured. Here’s how it works for this manufacturer:
- The number to the right of the trademark is the date code
- A single digit date code generally means the bottle was produced before 1947
- A single digit date code with no period “.” indicates a date in the 1930s. For example, “5” is “1935”, “2” is “1932”, etc.
- A single digit date code followed by a period (“4.”) indicates a date in the 1940s. For example,”5.” is “1945”; “2.” is “1942”, etc.
- From 1947 forward, all date codes were presented with 2 digits. For example, “53” is “1953”, etc.
- If the date codes are worn or damaged, you can also guess at the date using the number to the left of the trademark. That is the factory code, and the factories had specific years of operation as described here.