It's a debate that has rumbled through philatelic circles since at least the 1950s (famous US Stamp Dealer and author Herman Herst Jr wrote about it in many of his articles, collections of which have been published as Nassau Street and Fun And Profit In Stamp Collecting and both of which are entertaining and educational reads well worth checking out!). Should mint stamps be collected as hinged or never hinged. Or perhaps more to the point, at what point chronologically should a collector stop collecting mint hinged stamps and only seek out never hinged copies of issues.
A look at stamp catalogues from various regions is little help as none seem to agree to any date in particular. Generally, Scott sets its values for mint as never hinged for most nations around 1945 or so. Some countries a little later, some (like the USA) in the 1930s. Scott also, at least in its Classic Specialized 1840-1940 Catalog, provides pricing for never hinged for issues before their cutoff date. One thing Scott very rarely does though is price items, or even give a rough guide to value, for hinged items AFTER the transition date. Does this mean hinged items issued after the transition date are worthless???? Surely it can't, but how do you value the items if there is no guide, even a rough one.
Other catalogues, as I note above, use different dates. The Gibbons catalogs make the transition form hinged to never hinged with the coronation of George VI in 1937. Again, no guide is provided as to what kind of a discount should be given for items issued after 1937 that are hinged, and even more perplexing, neither is any suggestion of a degree of premium never hinged items issues before 1937. At least none is given in the three specialized Gibbons catalogues I own (Australia 9th ed, New Zealand 5th ed and Malaysia-Singapore-Brunei 4th ed).
Since I am focusing at this time mainly on the French colonial world, I also have a set of Maury catalogues for France and empire. Here there IS some help, as Maury prices everything from start to its general transition date of 1960 in both never hinged and hinged varieties. Interestingly enough, the degree of premium for Never Hinged items in the later 1950s vs hinged is not that large, usually around 33% or so. After 1960 prices for mint stamps are for never hinged only, though one could argue that the discount should not be too huge for hinged if the examples of the late 1950s pricing ratios are taken into consideration. Similarly the Afinsa catalogues for Portugal and Colonies offer pricing for both never hinged and hinged stamps up to 1953 and the Centenary of Portuguese Stamps issue. The İsfila catalogue for the Ottoman Empire and Turkey sets the date at 1938, while the Guillermo Jalil catalogue for Argentina sets it at 1940, with both catalogues providing pricing guidance for never-hinged items issues before their transition dates, though not after.
Stamp mounts only began to become common in the USA with the introduction of the Crystal Mount by the HE Harris company in the 1950s, though there were some predecessors that, to be honest, were more work than worth the effort to use. I remember Crystal Mounts well, since that is what my father used when he introduced me to stamp collecting in the 1970s and 1980s. I remember spending many an snowy upstate NY evening helping him mount his various collections with these mounts, that only came in a small range of sizes so that one had to fold over part of the mount to secure the stamp inside.
Crystal Mounts in their packaging from the 1980s...images that bring shudders of horror to me today.
(rant) I truly LOATHE Crystal Mounts (/rant). It was always way too easy to bend perfs as you folded over the extra plastic, and stamps often have a hard time "breathing" when they are in tightly folded ones. When I inherited my father's stamp collection, I discovered that removing stamps from mounts was rather akin to extracting a coin that has fallen thru a grate - often frustrating and infuriating. You need to be very careful removing the stamps from a Crystal Mount, and you often need to put it under some weight afterward to remove the -curl- that the mounts often create after years of storage. Really poorly stored collections housed in Crystal mounts often have yellow staining where the gummed strip was positioned, and occasionally the gum will even glaze from moisture trapped over time.
When I was heavily building up my first stamp collection in the 1990s, I used the traditional album pages and Scott Mounts, as I've noted in my first post. At times it felt like I was spending as much on supplies as I was on stamps. But this time around I have decided to use Lighthouse Vario stockpages and it is so wonderful NOT to have to factor the cost of mounts into my stamp budget AT ALL. Although they have come down in price from what they were in the 1980s when I was trying to convince my father to switch to Scott mount and stop using Crystal mounts (an arugment he eventually came to accept in the early 1990s) they are still not cheap especially when you consider the range of sizes you need if you are a worldwide collector.
But back to the original question - hinged or never hinged. In the end, this is something that each collector has to decide for himself or herself. De gustibus non disputatum est. My general rule of thumb is hinged is fine until 1960, and from 1960 onward I will only buy never hinged issues. By 1960 you really have huge supplies of never hinged material for most nations available in the marketplace here in the USA, and stamp mounts by 1960 were much more commonly in use. Some nations I may make the never-hinged only transition a bit earlier, but 1960 is, for me, a pretty firm date for all nations. Now, if given the opportunity to purchase pre-1960 material in never hinged form at a fair price, then I will not turn my nose up at it either, but for me at least, there is nothing wrong with a hinged stamp, provided that the hinging by previous owners has not done any major physical damage to the stamp over the years, such as thins on the back. For my part, so long as the stamp remains in my possession, I will not harm it further with another hinge. But let us be honest, we admire our stamps for the designs on the front, not to fetishize the pristine-ness of the gum on the back.