Dyeing hair with melanin precursors in the presence of iodate and peroxide
CA 2290098 A1 · Owner: Wenke, Gottfried · Inventors: Wenke, Gottfried; Prota, Giuseppe
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention concerns improved processes for dyeing keratinous fibers especially hair on the human scalp using a two-step oxidation process for the oxidation of the melanin precursors 5,6-dihydroxyindoline (DHIN) 5,6-, dihydroxyindole (DHI), and derivatives thereof such as 5,6-dihydroxyindole-2carboxylic acid (DHICA).
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 April 9, 1998. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended April 9, 2018.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 9, 2020.
- 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.