Question

Why do very old glass objects appear slightly milky instead of being transparent?

Answer 1

Hi friend,
Like liquids amorphous solids have a tendency to flow through very slowly.Therefore sometimes these are called pseudo solids or super cooled liquids. Glass panes fixed to windows or doors of old buildings are invariably found to be slightly thicker at the bottom than the top.This is because the glass flows down very slowly and makes the bottom portion slightly thicker.The long alternate expourser  of light and dark due to day and night causes the heat difference which may convert amorphous to some crystalline form and this makes the appearance of glass milky.
Hope it helps.

Answer 2

Answer:

Explanation:

Glasses are made up of silica. It is partially crystalline and partially amorphous. As timr passes due to changes in temperature of the system, it becomes crystalline as some of the atoms become more arranged. It absorbs water and forms a layer which results into cloudineds of glass. Thus, the glass appear milky