1770 working class envelopes question.

I’ve been looking around trying to figure out what would have been the working classes envelopes for there letters. Since a lot of the images shown on google look as if they are an interpretation of letters made for like weddings and such Im not taking them as my instant answer. I’ve noticed most consist of the letter simply folded and wax sealed shut, but the few others I’ve seen are actually in an envelope waxed then stamped on the front. (Which could be higher class or google shuffling another era into my results) I’m assuming that the working class if they could afford to send a letter would only fold and seal. Basically I’m looking for confirmation on weather I’m assuming correctly or not. Thank you and take care.