Patents by Inventor David J. Fenn

David J. Fenn has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method of indicating the presence of an impregnant in a substrate
    Patent number: 4311479
    Abstract: The invention is a method of indicating the presence of an impregnant, e.g. an antimicrobial composition, in cloth to provide visual evidence of the continuing activity of the impregnant. The antimicrobial composition in the cloth is activated on contact with a liquid such as water and is ionically bonded to the cloth. Small portions of the impregnated cloth are dyed with an indicator dye which bonds preferentially to the antimicrobial composition so that when the antimicrobial composition is exhausted, the dye will disappear from the cloth. The dye is preferably applied to the cloth in stripes.
    Type: Grant
    Filed: June 23, 1980
    Date of Patent: January 19, 1982
    Assignee: Exterma-Germ Products Ltd.
    Inventors: David J. Fenn, Adrian N. Fellows