A composite griddle plate comprising a first sheet of metal defining a cook surface and a core plate of a metal having a relatively high coefficient of heat conductivity wherein the first sheet remains in intimate contact with an upper surface of the core plate with the aid of a vacuum. The present invention also embraces methods of making these antiperspirant salts and solutions and compositions containing same. The method of generating the test signal includes generating a first time segment associated with a first frequency sub-band of the overall frequency band and generating a second time segment associated with a second frequency sub-band of the overall frequency band.