The glass in old windows can be the pretty early 'plate' or 'broad' glass to 'crown' or 'cylinder'.[five] Previous glass is recognised by its imperfections ('ream') which cause optical distortion. Draught proofing for sash windows will involve sealing the gaps by which air escapes whilst keeping the window’s operation. This https://trevorhyiqx.answerblogs.com/36076829/detailed-notes-on-sash-window-draught-proofing