You can find these seals at any office supply store. A regular sticker won’t stick to the paper as well as a postal seal.
These envelopes may still be opened intentionally so you’ll want another security mechanism if you’re concerned about this.
Most sealing wax comes in bars with a wick in the middle, much like a candle. Light the wick and hold the bar over the flap until a small amount of wax accumulates. The appropriate amount of wax should be able the size of a quarter. Some sealing wax comes in small pellets. Place one in a microwave-safe dish and nuke it for about 30 second. Then slowly drip it over the flap. You could also purchase a seal stamp that leaves a distinctive shape in the wax.
If you only have one-sided tape, fold it back on itself so that the sticky side is pointing out.
Use the brush that comes with the nail polish to gloss a thin layer over the adhesive strip.
A similar option is to place your content inside a greeting card and then place the card in the envelope. [3] X Research source
