The third column in the table below describes the changes in the manufacturing process and the first time it changes, links are provided to photographs showing the detail. By looking at factory dated lighters we can make some assumptions that that the lighter was made either in that particular year or maybe the year before. All of these can be used to help date the insert, and when used with the case dating chart above can help to give a more accurate date of manufacture... Zippo switched to using chrome plated steel for their lighters. These cases can have a tendency to look yellow and are non magnetic. One thing to be aware of is that some people may have swapped inserts between lighters in their collection in the past, so it can be possible to find brand new in box lighters where the insert and case do not match. Much research remains to be done and this page will be updated as this research continues. Lighters made in early 1946 have a case made from Nickel-silver. 1946 to 1953 Inserts During the period above, there were a number of alterations made to the insert. ... .