Not every stamp is ready for a permanent spot in an album the moment you get it. Duplicates waiting to be traded, new arrivals waiting to be sorted, stamps you haven’t decided where to file yet, all of it needs somewhere safe to sit in the meantime. That’s exactly what glassine envelopes are for.
They’re translucent, acid-free paper envelopes, small, inexpensive, and specifically designed not to react with or damage a stamp’s surface the way an ordinary paper envelope can over time. You can see what’s inside without opening it, which makes sorting a stack of loose stamps dramatically faster.
They’re one of those supplies that feels almost too simple to matter, right up until you don’t have any and you’re stuck deciding between leaving stamps loose in a drawer or reaching for whatever envelope happens to be nearby. A stack of these costs next to nothing and solves the problem permanently.
If you’re just getting your supply kit together, this is one of the cheapest, easiest additions you can make.