I have recently had double glazed windows fitted. The windows are supposed to be pilkington k glass. Some windows had stickers on them saying the the glass with the sticker should be fitted facing inwards.Some of the pane had the sticker facing outwards. I queried this with the window fitter and they said the stickers were wrong not the window. Is there any way to check the glass is the correct way round. Also is it possible to check k glass has been used?