Stamp collectors world-wide can use them.
I meant in a collage, a mail art.
You can put portraits in it to make a collage about 'forgotten people'.
Thank you Carien and Bradford
I was thinking of dyeing the envelope (paint, ink). To use in a junk journal.
The French Post sent me the beautiful stamps I use for Mail Art in these envelopes. I order them on the internet because we hardly find these stamps in post offices.
I end up with about fifty of these envelopes!
I hesitate to use it to send mail because I fear that it will tear.