The first stamp used on the base of the lighter bore the legend "PAT. This was used on lighters manufactured until around the end of 1950. There are many examples of "Pat Pend" cases with "Pat 1950" inserts (see below) these lighters would have been made around the time of the changeover at the end of 1950 using stock cases and newer inserts.The next bottom stamp used is the most confusing of all.I am going to start with the last undated lighter as this is the easiest to date.
There is still much work and research to be done, and this page is by no means complete.
If you can add any information please feel free to contact me The factory in Canada opened in 1949 and closed in 2002.
The lighters were stamped "Patented 1950" and many people think that this is the year of manufacture of the lighter.
This stamp was used until 1967 and a lighter with this stamp could have been made anywhere between those dates.
Codes were not used on the lighters until 1987, so we have to look closely at the bottom stamp and the insert to try to determine the date of manufacture.
It is not unknown for Lighters from Canada to to be shipped with Bradford stamped inserts, so this can sometimes be a help.1982-1986 Dating guide In July 1986 the line symbols were discontinued and the lighters were then identified by a series of roman numerals.These were placed to the left of the word Zippo, which left the space to the right free.Early 1986 lighters of this series do have earlier date codes.This series continued until 2000 1986-2000 Dating guide In March 2000 the roman numerals were supplemented with the actual year of manufacture (2000) printed below the roman numeral (XVI).There are numerous sites around the internet that give dating charts for Zippo Lighters, and there are also dating guides in many of the Zippo Books.