by Arthur H. Groten

What constitutes a letter? A letter is the reason for the existence of the covering that contains it. From the earliest days through the mid-19th century, the vast majority of letters were sent folded and sealed, first with wax and later with wafers.

What was of paramount importance to the correspondents? The privacy of the contents, and how to achieved it? Given the importance of sealing the letter to ensure privacy, there is surprisingly little information on how that privacy was maintained.

There is but a single book dedicated to this topic, Adhesive Wafer Seals by Michael Champness and David Trapnell (1996). Passing note of them is made in Michael Finlay’s Western Writing Implements (1990).

My British colleagues know of no other significant references. In this article, we look at various intrinsic methods of sealing a letter during the 19th century. Prior to 1839, postage was charged based on the number of sheets and distance; an envelope, then, would represent another sheet and thus increase postage cost. It was not until the introduction of the uniform Penny Post (based solely on weight) that envelopes as we know them came into general use.

Initially, envelopes were not gummed and therefore had to be sealed by some other method, as noted above. By the late 1840s, envelopes appeared that had glue applied to the inside of the tip of the flap. There were often designs embossed in that area to give the appearance of an applied matrix or wafer.

Even so, wafer seals can be found used in conjunction with such pre-gummed, even embossed, flaps. Even with the advent of fully gummed envelopes, wafer seals were still used, often by merchants to promote their business, products or services or by special interests such as religious or temperance groups.

This practice continued well into the late 19th century when the wafer seal was gradually replaced by the poster stamp for those purposes.