Soluble nylon is a chemically modified form of nylon produced by treating nylon with formaldehyde. It is soluble in alcohol, or alcohol and water, and is particularly useful when flexibility and penetration are required, as in an adhesive. Soluble nylon film is used in archival restoration as an adhesive backing for fragile documents, in which case it is applied by heat. It is also used in resizing paper. See also:NYLON SIZE ; SEWING THREAD . (198 , 235 )