Bone glass: the fearsome-sounding collector’s treasure that feels like glass but looks like porcelain
Fact or fiction: bone glass is made from bones, and milk glass from milk? Here’s how to tell opaque or translucent white glass varieties apart.
White glass, opal glass, opaline, milk glass, bone glass—they’re all opaque or translucent varieties of white glass, but how do they differ? In opal glass, one ingredient is often phosphate, which scatters direct light and turns clear glass cloudy. White opal glass is commonly used in lamp shades.
Also known as milk glass, white glass can be tinted to produce milky tones. However, no actual milk is used in its production. The phosphate required for bone glass, on the other hand, comes from bone ash derived from livestock, making these pieces unsuitable for vegans. Bone glass was used, for instance, in old pharmacy bottles.
Distinguishing bone glass, opal glass, and opaline can be tricky, but it’s possible by holding them up to the light. If you notice an orange-yellowish tint in the white glass or around its edge, it’s bone glass. A transparent glass with a slightly bluish cast is opaline. Opal glass stays white even in bright light.
In Finland, Riihimäen Lasi produced bone glass items, though they’re relatively rare. American manufacturers made more bone glass pieces, and some of them found their way to Finland as well.
