Alongside our seals and sticks of sealing wax at Castle in the Air, we offer a free little handout from the early 1900s describing how to properly seal an envelope. If you're one of our readers who hasn't yet made it into the store, this one's for you!
Do not begin by thrusting the end of the wax into the flame and conveying it in a flaming spatter to your envelope. Take plenty of time and hold the wax above the flame of the candle, but not near enough to burn (about one inch); a burnt wax makes a streaky seal and is hard to manage.
When a marble-sized amount of wax has gradually softened, but is not dripping, apply it with a circular movement upon the place to be sealed, rub it around and down until you have a circle of proper size and thickness, then pull straight up and apply the seal. The result should be a clear-cut impression.
And remember, if you're planning to send your wax-sealed envelope using the U.S. Postal Service, it will need another 20 cents of postage for hand-cancellation.