Covers that are dated,
of course, pose no problem, nor sets that are known to have been
issued in a certain year, but, for the vast majority of covers,
unless youre ready to make a career of studying covers,
the best you can hope for is narrowing down your guess to within
a factual range of years.
The length of the cover,
the width of the striker, the use of certain types of footers,
all are indicators of age. Still, it's possible to narrow the
general time period that a cover comes from to a somewhat more
precise range of years.
For example, if the
cover youre trying to date is a front-striker, you know
at least its pre-1979 (the last front-strikers appeared
Also, for most of the manufacturers,
we know the years of operation.
The only general dating
guide, and by far the most comprehensive ever done, is the MM Dating Guide. This guide lists the known range
of dates for specific manumarks. As ongoing research reveals
more information, the guide is normally updated annually. It
currently runs 119 pp. and lists thousands of different manumarks.