Dust Mask: Rigid Perforated Guard with a Replaceable Cloth Filter (Swindell, US 2,681,060, 1954)

A simple dust mask for workshops and plants. A rigid cup with air holes covers the nose and mouth. A cloth filter lines the inside and folds over the cup's rim, held by wire clips: the air passes through the cloth, and the cloth also pads the rim against the face. Change the cloth and the same mask can pass from worker to worker. Result: a nose-and-mouth dust mask with a filter you can replace. Source: M. E. Swindell, US 2,681,060 (1954). Unknown: sizes, how the cup is formed, the cloth. Picture: the patent drawing.