Updated: Aug 23, 2022
The shape is a hand, curvy on the bottom and long ridges on the top.
Origin story: This shape was meticulously cut from craft foam by an RIT student in Professor Deborah Beardslee's Graphic Design class. The student created this icon to represent the 'clean' button on an oven. The visually impaired testers approved.
As I labeled more appliances the simple 'clean' button icon was changed to a diamond shape. The diamond was also a positive representation in our initial testing. The hand shape is now used for the 'hand wash' feature on washing machines.