Coated products

The invention relates to barrier coatings to prevent migration of alkali metal ions from a glass surface. The barrier coatings are deposited by pyrolysis of a silane gas on the glass surface above 600 DEG C in the presence of a gaseous electron donating compound, whereby oxygen from the glass is incorporated with silicon to form a transparent barrier coating up to 50 nm thick on the glass surface. The barrier coatings are used to prevent migration of alkali metal ions into overlying layers sensitive to alkali metal ions e.g. in glass coated with electroconductive or infra red reflecting coatings, and in liquid crystal displays.