Making glass articles with defect-free surfaces
CA 2061941 A1 · Owner: Dumbaugh, William H. Jr. · Inventors: Dumbaugh, William H. Jr.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention is directed to a method for making a glass article having at least one surface which is essentially defect-free and is at least equivalent in smoothness to a polished surface. The method generally comprises the steps of:, (a) bringing into contact with each other a body of a glass which is relatively insoluble in an acid solution and a body of a glass consisting essentially expressed in, terms of cation percent on the oxide basis of 70-85% B2O3, 7-20% BaO, 0-10% PbO, 0-12% R2O wherein R2O consists of, Li2O+Na2O+K2O 3-15% PbO+R2O, said glass from its setting point to room temperature having a linear coefficient of thermal expansion within about 5x10-7/°C of that of said …
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed February 27, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended February 27, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 27, 2014.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.