The subject invention pertains to materials and methods for stopping or decreasing the blood flow from an open wound or medical or surgical procedure. Compositions of the invention comprise a salt form of a cross-linked polyacrylic acid. In one embodiment, the composition comprises a sodium salt of a polyacrylic acid. Compositions of the invention can also optionally comprise one or more different salt ferrates, and/or a cationic exchanger resins, and/or a silver compound. In an exemplified embodiment, a composition of the invention comprises sodium polyacrylate provided in a dry powdered form. Polyacrylate compositions of the invention can be applied directly to a wound or treatment site, or they can be incorporated into a wound dressing, such as a bandage. The clot or scab formed at a wound or treatment site treated with the present invention is extremely elastic and exhibits considerable tensile strength when stretched to the breaking point. The subject invention also concerns wound and surgical site dressings and coverings, and methods of using a composition of the invention to stop blood flow from an open wound or treatment site.