Glass colour changes

Read the whole patent

Listed from its IP Australia record in Patent Yard's archive of Australian patents past their term. Its claims, description and drawings are in the AusPat record and on Google Patents, and the Claude kit works from them.

Why it's free to use

• Filed July 6, 1973 and granted January 14, 1975. An Australian standard patent lasts 20 years from its date of patent, which is at most a year after this filing, so its term ended by July 6, 1994.
• A pharmaceutical extension adds at most five years, so even that would have ended by July 6, 1999.
• We check Australian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.