R4 Wax Seals Primer Re-issue
This episode is the wax seals primer.
Intaglio seals are cut into the surface of the matrix. Intaglio seals are most commonly used for wax seals and create a design in raised relief in the wax.
Relief seals have designs that are above the surface of the matrix. Relief seals are commonly set behind a piece of paper for embossing that also creates a raised relief design. If a relief seal is used in wax it creates an impressed design more like a mold.
Letterlocking
http://letterlocking.org/about
https://www.atlasobscura.com/articles/what-did-people-do-before-envelopes-letterlocking
My personal favorite method is to use wax beads in a wax furnace to heat the spoon with the wax in it and the spoon gives you more control over how the wax is applied to the letter. Melting wax beads in a spoon also gives you the ability to mix wax colors to add to the character of the seal.
Non-machinable postage
And a few links from the Wax Seals Revisited Episode
https://www.carolinapencompany.com/custom-wax-seal
https://vanness1938.com/collections/wax-seals
J.Herbin Wax seal ink pads
Global Solutions Metallic White Shimmer Stamp Pad
Glue gun wax - especially clear wax