mystery of first flight covers.

My grandmother got FDC's routinely, which were self addressed to her, sometimes with a pre-printed address label of the next door neighbor who apparently had the "connection" for getting the FDC's...  the address is in my grandmothers handwriting..... 

I know for a fact Mrs. Maynard (neighbor) was not mailig the FDC's, and most of the FDC's are unsealed and Mrs. Maynard's address lable would actually be under some or all of the flap had the envelope been sealed...

I recognize her handwriting.  I have  quite a few of them.... unfortunately, many of my grandmothers FDC were stuck to adhesive photo album pages (cornerless!).  A couple of times I would receive one, but I think these were unaddressed they received  duplicate sof and just wrote my name/address on.... (and I have a couple where I printed my name and address, monkee see, monkee do!)

she also liked to part of blocks and sheets to affix to pages....

Below is one of the few with a cancellationon the reverse, but notice, envelope was never sealed, and if it had reverse cancellation would not be where it is

Nov 17, 1962 Dulles International Airport- handwritten address is my greandmothers, and she never ewver visited the east coast... or flew in an airplane/jet.




here's the backof the FDC, unsealed with Nov 17 cancellation Newark, NJ Airport Mail Facitity-  note position of cancellation

(Dulles Airport is actually in Dulles, VA so how it gor to Newark is a mystery)



and here is the back of envelope with "flap down" ....

I may be misunderstanding the question, so hopefully this answer is applicable. To get a first flight cachet and cancel, you would address and stamp the envelope yourself, keeping the address to the right so it would not overlap the cachet that would be later applied. You'd also insert a postcard sized enclosure in that envelope to stiffen it so your envelope would get a good cachet imprint. You would then enclose the envelope in a larger envelope addressed to the post office doing the first flight cover, with instructions to hold for the first flight.

As for the unsealed envelope, I believe the envelopes were returned as they were sent. The person (your grandmother) could seal the envelope, or if they wanted the option to remove the stiffening postcard sized enclosure, they could just tuck the envelope flap inside the envelope without licking the gum. I have a number of collector created covers like this.

For the overseas first flights like the one addressed to Greece, this newspaper article from 1947 might help explain:


Not all first flight envelopes were created as collectibles. Some were ordinary mail that happened to be sent that day, such as this letter sent from my great grandmother to my grandmother (while she was visiting the states from the Canal Zone, and apparently from the addresses on the envelope, hard to pin down) 
thestampforum.boards.net/post/61376/thread

stainlessb - I had forgot about that part of your post. Yes, FDCs were often purchased from the postal service stamped and cancelled but unnaddressed (in bulkas well). I have some of those too, even sheetlets of postal buddy cards with 4 FDC cancelled cards. As to value, I don't know which have more value, addressed or unaddressed. I had the idea in my mind that unaddressed were less valuable since they're a bit like CTOs, i.e. cancelled but not genuine postal use. I certainly could be wrong, as I haven't looked up values. I guess since an unaddressed envelope can easily be turned into an addressed envelope, it's a weak distinction.