The glass in previous windows may be the very early 'plate' or 'wide' glass to 'crown' or 'cylinder'.[5] Old glass is recognised by its imperfections ('ream') which bring about optical distortion. C – Parting bead. There are 2 parting beads positioned on both sides of your sash box, working vertically from top https://skin-cosmetics04791.blogripley.com/36587102/facts-about-sash-window-draught-proofing-revealed