Although it is not the first thing that the newcomer to the world of antique glasses frames thinks of, the material that antique eyeglasses are made out of is one of the many keys to determining when they were made, and is an interesting subject in its own right. The clever, labor intensive techniques developed to turn such unlikely materials as leather and cow horn into slim, precise, lightweight eyerims, bridges, and temples is a testament to mankind's capacity for problem solving and a fascinating glimpse at how high quality items were made prior to industrial production.
The most persistent material for spectacle frames is, naturally enough, metal. Many of the finest spectacles of the early American period, imported from Europe for the most part, were framed in silver or gold, but these precious metals fell victim to their value in most cases and were melted down once the original owner was no longer wearing them.
Other metals survived human cupidity more readily, and metal framed spectacles are to be found from the days of the ill-fated Jamestown colony up to the modern era of the Internet.
Leather was an extremely popular material for antique glasses frames, mostly because it was cheap for the purchaser. Some of the earliest surviving rivet spectacles from medieval Europe have still-intact leather frames, and the British colonies in North America often witnessed European lenses fitted into leather eyerims.
The leather was boiled to soften it, then cut into the fine shapes that were molded to the form of eyerims, bridges, and so on, and finally placed in cold water to harden it again, which made it nearly as hard and long-lasting as wood. Leather was finally displaced as one of the main construction items for spectacle frames when mass production of metal frames became possible in the 19th century.
Horn was used for a huge variety of small objects, including knife handles, antique glasses frames, utensils, decorative boxes, buttons, and many other uses. The horn used was either ordinary cow horn sliced off in layers and flattened, or baleen from the feeding plates of whales. The horn was pressed hard between two red hot metal plates before being quenched in cold water, tempering it into a dense, hard, tough, fine-grained form that could be carved into sturdy glasses frames.
Tortoiseshell is the shell of sea turtles harvested and cut into antique glasses frames. It provided a more colorful type of frame, and is in a way the ancestor of plastic frames. Tortoiseshell continued to be used until long after leather and horn fell out of common use, though it is no longer used today when sea turtles are seriously endangered.
Plastic is a true neophyte on the scene where antique glasses frames are concerned, but there are plenty of funky, psychedelic glasses and sunglasses from the 1960s that made excellent use of it for their extravagant purposes. The problem with plastic, of course, is that it cannot be repaired once it breaks, and it is often fairly brittle, too. It can be glued, but the join is visible as a permanent crack, which lowers or eliminates the eyeglasses' collectible value.
Nevertheless, there are many fun plastic glasses still available for the collector, with many of the vintage types, such as John Lennon glasses, displaying vivid colors, huge, goggle-like sizes, and sometimes strange shapes, too.