Exactly what is the procedure for removing a single self-adhesive stamp from a sheet, booklet, or souvenir sheet while keeping the backing intact and not hanging outside the perforations? I understand there are some press sheets and die cast sheets where the perforations go through the backing making it easy to separate individual stamps. When I buy a single stamp (self-adhesive)from a dealer how do they manage to provide a stamp that doesn't look like it was just cut out with scissors?
For coil self-adhesives, I just fold the liner from the backside approximately where the die cuts would be and Xacto it. It leaves the die cut perfs hanging over the liner a little. It's easy since it's a coil and liner alignment is easy.
For self adhesives with die cuts on 4 sides -- dunno...do you take the time to Xacto 4 sides if you're a dealer? I don't know, but I've seen obviously hand torn and scissor cut ones that look so bad that I'd rather buy a new example.
When taking a modern self-adhesive single from a pane, I do leave about 2-3 mm of paper all the way around. I trim it long and straighten the cuts out with a stamp mount guillotine.
But that wouldn't work if intending to split all the stamps into singles/blocks for sale.
If you wanted it even with, or at the interior edge of the perf, I'd do as Gwanghoops suggested and fold the paper back and cut it with an Xacto or razor blade. The only problem I have with leaving the perf's hanging in the wind would be their tendancy to get stuck on anything, if they do, the gum on the perf's will be disturbed at best and you're no longer mint all over.
As a side note, I almost wish the backing paper was black.
I purchase the U.S Stamp Yearbooks (what used to be called the mint commemorative sets), one of the reasons being that it has singles, so I don't have to buy the whole sheet if I don't want it.
I've wondered how the postal service separates all the singles for these sets, sometimes the perforations appear to be perfectly cut around, with the backing still on the adhesive side. It looks like they may have a machine that cuts the stamps out of the pane.
I've not been too happy with my attempts to either cut exactly at the perf tips, or to peel back the perforated edge, cut the backing to separate the stamps, and lay the perforated edge back down.
What I've been doing is using for postage the stamps around the single, block, or strip I want in "collectable condition" Then I can make nice straight cuts around the edges leaving a consistent boarder just beyond the perforations.