Of our packaging materials, glass seems the most inert – non-porous, non-reactive, impermeable, recyclable.

But glass is secretly unstable; and as it ages, glass decomposes.

Alkali ion depletion on the surface cause migration of other ions, leading to the formation of layers. Called weathering, pitting, grooving, etc, it results in cavities, films, crackles, dark areas swallowing light, silver or milky or iridescent scales growing on the surface as the glass slowly stops holding itself together and prepares to crumble into dust.