US Patent No. 9,844,500 B2; Kao Corp., Tokyo, has patented a process for semi-permanent hair straightening. It entails applying a solution comprising glyoxylic acid at a pH of 1.5-2.1 to prewashed hair, keeping the solution in contact with hair for 15 to 120 minutes, wherein said keeping has an average duration of 60 minutes; drying the hair, and straightening the hair with a hair straightening iron at temperature of approximately 200+/−50° C. The glyoxylic acid is dissolved in an aqueous soluti...