Latex Gum/Adhesive is applied in two strips to make envelopes self-sealing. The seal is made when the latex strip on the flap makes contact with the latex strip on the body of the envelope.

Pressure Sensitive Gum/Adhesive is activated when the gum is pressed against paper. The gum is covered with a release sheet, which the user removes when he is ready to seal the envelope.

A Clasp may be used with remoistenable gum to seal some envelopes. The clasp is passed through a hole in the flap and spread to hold the flap closed.

String and Button closures are useful because they can be reused many times. The string attached to the flap is twisted around the button on the body of the envelope to complete the closure.