I may have written this in another "hinge thread," but I'll do it again here.
Dennison hinges are the gold standard but, as has been said, are not made anymore for unknown reasons. One story is that they used glue made from expired horses whose tissue was processed into the gluey substance then commonly used to make glue -- and that was later prohibited so the glue could not longer be made. Animal-based glues, although they may seem a bit gruesome today, were very common for generations. After all, ladies wore the pelts of small dead animals around their necks and shoulders so this kind of thing was just accepted as normal.
The story of animal glue being banned as the reason these hinges stopped being made might be possible, I suppose. The problem has always been that there is absolutely no evidence to prove this. And the existing Dennison hinges have never been tested, as far as I know, to see if they do, in fact, contain glue made from animal tissue, and you'd think that would be fairly easy to do. I still use old Dennison hinges at times, and I never feel I'm licking animal glue -- for what that may be worth! "Yum, the pleasant taste of an old, expired horse!"
The copycat "Dennisen" (with an "e" and not an "o") hinges are some company's obvious attempt to capitalize on the name of the once-popular hinges by misleading customers. Even today, Dennis"e"n hinges sell on
ebay for inflated prices to people who I imagine think they're buying the other similar-sounding brand and are willing to pay high prices. Caveat emptor, as they say. It's allways bothered me that these are allowed to be sold since it's such obvious deception -- like buying an "Appul" computer or a "Rollex" watch (which I've actually seen for sale on the streets of New York!").
What the secret of Dennison's glue was is, well, still a secret we may never know. Some speculation in this thread may be correct -- that the glue was applied in layers (I've never noticed that myself) or that it's somehow applied in a checkerboard pattern which I also have never noticed. I think just looking at the hinges with a good magnifying glass, the low-tech way, would show these characteristics, but I can't see them, myself. So the mystery remains. If you find out, let us know!
Subway Stamp Shop in Pennsylvania tried some years ago to recreate Dennison hinges. Apparently, they managed to find and purchase some of the original Dennison hinge-making equipment, but later found they still could not make the hinges properly. It may be that they could not find the right glassine paper, but more likely, they could not recreate the glue which had once been used. They called these hinges "Dennis's hinges" (after a young relative named Dennis, I understand), but they were not anywhere near as good as the real thing. They may still be for sale.
All modern hinges, as has been said a number of times, are made by the same company in Europe -- which I think is Prinz. No matter what brand is on the package, they are Prinz-made hinges. AI says it's a "company called Prinz Verlag GmbH based in Germany." So thanks to Prinz for continuing to make hinges or we would not have a single modern packet of hinges to buy anymore.
Hinges having largely gone out of style makes them most likely not a big profit item for anyone to make. But they probably would appeal to new collectors. I have a massive stamp collection (100 albums) and even sophisticated little me still uses hinges in my Scott International album -- but not in my country-specific albums which only use mounts, some clear and some black.
I use hinges in my International album for a few reasons. Those stamps are my duplicates and are usually used stamps with hinge marks already on them, so why not use hinges? Using stamp mounts also makes the pages a great deal thicker so the album quickly begins to bulge, and I don't want that in these albums or I'd need dozens more binders (and my wife would kill me). Using mounts keeps the albums much slimmer and they still look good in a kind of old "classic" stamp album way that I still like.
As for other brands of hinges similar to Dennison, obviously none of the modern brands will be the same. But even older brands no longer produced like Scott hinges and Fold-O, and so on, are not really similar. A Canadian company sells imitation or fake Fold-O hinges, I believe, so beware if they say "Made in Canada". I do not think they are the same hinges. I once tested about 25 different brands of older and newer stamp hinges, probably every brand you are likely to encounter new or on
ebay where I found many of them, and all of them were just terrible hinges. When removed -- which is of course the key thing here --they all peeled the album paper badly and damaged the stamps they were applied to. Every single one of them. There was no brand, including among the older hinges, that was nearly as good as Dennison hinges which are outstanding in being able to be removed easily with no damage.
This is why Dennison hinges sell for so much today. And although packages and even boxes of them are sometimes found (please tell me where I can find these boxes!), they must be drying up by now. I bought a few on
ebay a while back when they were an "outrageous" $10 a package -- with some discomfort because of that high price. Today, they sell for a lot more than that! I have enough packages of Dennison hinges plus some others so I may be okay.
I often cut them in half especially for smaller stamps. Even with modern hinges, cutting them in half reduces the likelihood of damage to your stamps -- as does not slobbering on your hinges. Just a tiny amount of moisture is enough and will allow the hinge later to be removed a little more easily. The number of times I've removed hinges from someone else's album pages which were nearly cemented to the page -- as well as to the stamp -- by a collector with a very aggressive use of moisture is far too many. And often with unused stamps, these collectors also manage to moisten the gum on the stamp so it gets cemented to the page in this other way. I end up in a bad mood when I have to rip stamps off an album page like this, and sometimes I've just binned the pages if they are common stamps since they cannot be removed without damaging them. "Lick lightly" should be the motto of hinge users. Another reason for the move to stamp mounts.
There are double-sided removable tapes today that I've played with but I am very reluctant to use them on stamps since who knows what damage they might eventually do. But maybe some of these adhesives will work on hinges someday -- like Post-It notes. Back in the 19th century, many collectors used the selvage attached to stamps to make "hinges" and that ruined a lot of those stamps. Not to mention the Scotch tape many of us once used when we were beginners which also ruined those stamps. Oh, the horror!