The following solutions and materials were used in the experiment: Lightning Powder PD kit, Sirchie PD kit, ODV PD kit, Lynn Peavey PD kit, the physical developer working solution routinely used by the U.S. Secret Service's Forensic Services Division, maleic acid solution, and vinegar solution. Eighteen paper samples were used in the experiments. Several different experiments were performed to test both the use of dilute acetic acid (vinegar) as an acid prewash as well as the ability of the four PD kits to develop ridge detail. The importance of the acid pre-treatment when processing papers with an alkaline pH was clearly demonstrated. These experiments have shown that vinegar may be used in place of other acids as a pre-treatment used prior to processing with physical developer. Of the 18 papers tested, only the fax paper and glossy pamphlet stock reacted adversely with the vinegar pre-treatment (as they did with maleic acid). In general, the working PD solutions prepared from commercially available kits produced comparable ridge detail to a PD solution prepared in the laboratory from the component chemicals. 4 figures and 16 references