Glass buttons have been around since the 18th century when the material was mixed with other materials to produce a button. It was not until the 19th century that pure glass buttons were produced. These were made with a metal shank or post. Glass buttons with a self (glass) shank are modern buttons, and by modern, I mean from the very early 20th century.
But how can you tell a glass button from a plastic one? This is fairly easy if the buttons are clear. Glass buttons sparkle, they are clear, they have a clarity that just cannot be found in plastic or synthetic buttons. Plastic buttons have a cloudy appearance. If the button is pressed or cut, the edges are sharp, just like cut-glass crystal. Glass is also cold to the touch (touch it to your lips, they are more sensitive to temperature). Tap the button on your teeth, it should be a sharp clicking sound not a dull thud! And of course glass buttons are heavy. Plastic buttons are very light. If in doubt check the back. If the button has a metal shank or post it is glass. The metal was inserted into the glass button while still hot.
In this picture there are 4 different backs. All of them are associated with glass buttons.
1. Loop shank with metal backplate. There are lots of variations and date to the nineteenth and twentieth century.
2. Metal loop shank with rosette back plate. These date from nineteenth to early twentieth century.
3. Metal box fourway metal shank, late nineteenth, early twentieth century.
4. Built up self-shank, twentieth century.
These were in my grandmothers collection and all date from the late 1800s early 1900s.
The same criteria apply when trying to identify coloured glass buttons. The sound, feel and weight come more into play here. These lemon zebra buttons are a great example of vintage 1930s glass buttons.
There are a large number of particular styles of manufacture for glass buttons …. but that’s another blog post!