Question

Why some very old glass objects appear slightly milky instead of being transparenr?

Answer 1

some of the glass pane ypu may see get milky because it undergo anneling

it is a process I. which some part of the pane turns into crystalline solid due to regular heating and cooling.

hope it hlps

Answer 2

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.