Antiperspirant active compositions and manufacture thereof

A method of making an antiperspirant active composition comprising:

• I) heating an aqueous solution containing a first aluminum salt having an aluminum to chloride molar ratio of 0.3:1 to 3:1 and a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat, and a molar ratio of buffer to aluminum is at least 0.1:1, at a temperature of 50° C. to 100° C. for a period of time of 1 hour to 6 hours to Obtain a first aluminum salt solution;
• II) adding to the first aluminum salt solution an aqueous solution of an inorganic base to obtain a second pH adjusted aluminum salt solution having an OH:Al molar ratio of at most 2.6:1;
• III) heating the second pH adjusted aluminum salt solution at a temperature of 50° C. to 100° C. for a period of time of at least 6 hours to obtain a third aluminum salt solution containing an Al30 polyhydroxyoxoaluminum cation;
• IV) heating the third aluminum salt solution at one of
• a) at a temperature of 100° C. to 250° C. in an isochoric reactor or under hydrothermal reaction for a time sufficient to form a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27Al NMR;
• or
• b) at 100° C. at reflux for about 10 days or greater;
• to form a fourth aluminum salt;
• and
• V) optionally adding an aqueous solution containing a zirconium compound to the second pH adjusted aluminum salt solution to thereby obtain a second pH adjusted aluminum-zirconium salt solution having a molar ratio of aluminum to zirconium of 5:1 to 10:1.