- Date the stamp using watermarks. Watermarks, the semi-transparent markings that are used as a security device for paper, are typically used for a period of time and then changed or eliminated. By knowing the watermark of the stamp you are trying to date and comparing it to known ranges of watermarks, you may be able to place the stamp in the correct era.
Be aware that watermarks are rarely used in more modern stamps
- Examine the style of adhesive. One of the trends of postage stamps is the use of self-adhesive glues in more recent stamps. Consumers favor the "peel-and-stick" experience as opposed to the "lick-and-stick" of old.
Fortunately, self-adhesive stamps have not been used that long. While there were sporadic attempts prior to the 1980s to issue self-adhesive stamps, it is in the mid to late 1990s that they begin to be used by more and more postal authorities. Self adhesive stamps are very popular with the consumer.
By knowing the type of adhesive available on the stamp, one can determine approximate years of a stamp.
- Perforation changes can reveal dates. Stamp perforations might reveal an estimated date of issue for a stamp. The perforations exist to enable a pane of stamps to be separated into individual stamps, and the various methods used over the years can help to date the stamp.
The very earliest stamps were issued imperforate, which means there was no method of separating stamps, other than scissors or a sharp knife. After that, the early stamps were sometimes rouletted, which is where sharp blades were used to make incomplete cuts between the stamps. The individual stamps were easier to pull apart but they usually had rough edges where they were separated manually.
Later, perforating machines were used to puncture holes in the margin between stamps so that they could be torn apart. The perforations themselves are probably of limited value in dating the stamps since the perforations have been used for decades, but recently, there are been some perforation changes that can be used to zero in on dates of issue.
More and more stamps, especially commemorative issues, and stamp perforations that are not the traditional series of holes, but have some simple cutout design in the midst of the stamp perfs. Great Britain has used an elliptical perforation for a number of years that complements the row of round holes. Canada has issued several recent stamps that have a maple leaf punched into the perforations. Knowing these types of special perforations can help one date a stamp.
Most newer self-adhesive stamps are die-cut. This means that a sharp cutter (a die) has cut through the paper leaving the stamp adhering to a backing paper. When needed, the stamp is just peeled off. The die-cuts leave a very crisp edge to the stamp, since it is lifted from the backing paper, and not torn, like the other methods require.
Over the last few days I've tried to list just a few ways that you can determine the issue date of a stamp. Each of these techniques is only good at narrowing down a stamp's issue date to a range of dates. Hopefully, these tips will reduce the amount of time needed to find the stamp in the catalog.