This taken off the net, but very informative.
Subway Stamps has purchased the old Dennison hinge equipment and reverse engineered old fashoned peelable hinges.http://www.subwaystamp.com/
G&K (part of the Subway Family) has purchased and rebuilt the original machine Dennison used for over 50 years to manufacture the best stamp hinge that was ever made. G&K is now using the original machine (completely rebuilt), the original Dennison gum formula and special glassine made to the original Dennison specifications.
They have named these after their grandson, Dennis, look for "Dennis's Stamp Hinges", Just like Grandpa used.
So far they have developed the Formula A stamp hinge for ungummed stamps. They are still working on a Formula B hinge for gummed stamps.
The following is from the Winnipeg Stamp Club (2004)
THE SEARCH FOR THE PERFECT HINGE
BY LEN KRUCZYNSKI
Though Dennison Stamp Hinges have not been manufactured for many years, they are prized by collectors. These familiar greenish hinges have remarkable adhesive properties: although holding the stamp firmly in place, they peel easily, never ripping or taking apiece of the stamp (or album page) along with it.
I recently opened a packet of Dennison hinges that had been purchased in the early '70's (priced at 35 cents per 1000): the hinges were still flat, separated easily and functioned as well as the day they were made.
Now, the first thing that comes to mind to explain the remarkable adhesive ability of the Dennison hinge is that it must have something to do with the gum. Being a chemist by training, I decided to use Chemical Analysis to see if Dennison gum was different from any other. The method of analysis used is called Infrared Spectroscopy: an infrared beam is passed through a thin layer of the gum, producing a trace which, like a fingerprint, is unique to each chemical substance.
The gum rinsed off three hinges was sufficient to do the analysis. In the process of removing the gum from the hinge, I weighed the three hinges before and after gum removal in order to calculate the percentage of the weight being due to the gum. The results of the chemical analysis are startling. All hinge makers use the same gum: dextrine. Dextrine is manufactured from potato or corn starch by boiling with minute amounts of acid. It has been available commercially since the '30's.
It is very common: it is the gum on most envelope flaps and has been used on Canadian stamps up to the '70's when it was replaced by Poly Vinyl Acetate, or PVA for short. Hinge manufacturers have tried to capitalize on the remarkable adhesive properties of the Dennison hinge. Collectors may have been fooled into buying "Dennisen" hinges, marketed in a package similar to the blue and red Dennison package. More recently, Subway Stamp Shop (2121 Beale Ave, Altoona, Pa. USA) is marketing the Dennis hinge, claimed to be manufactured on, and according to, Dennison specifications of paper and gum.
Here are the results of my analysis of six different stamp hinges put into three categories:
1.THE BEST: peel easily, never rip, never take a "divot" out of the stamp or album page.
Dennison (26 % gum)
2.ACCEPTABLE: peel if you are very careful; sometimes rip, sometimes take a "divot" out of the stamp and/or page.
Dennis (16 % gum)
Unitrade (33 % gum)
3. POOR: almost alway rip when removal attempted; often removing part of stamp or page.
Gibbons (39% gum)
Fasto (42 % gum)
G&K(38 % gum)
And now for some comments and conclusions.
Gibbons hinges are made in Germany, as are Fasto; they appear to be one and the same hinge.
G&K hinges are also marketed by Subway.
One striking trend that may explain Dennison's secret is the amount of gum. The best hinges have a smaller amount of gum.
The only conclusion that I can come to at this point is that Dennison's secret may lie in that greenish (glassine) paper. Does it have some sort of wax that causes the peelability?
The hunt for the perfect hinge goes on!