Wetwop - BLACK or WHITE Wetwop™ is a pre-mixed liquid that produces excellent friction ridge detail when used to develop prints on any adhesive surface, such as masking, duct, clear, cellophane, brown packaging, and nylon reinforced strapping tapes. •Indefinite shelf life •Requires no mixing •Simply shake and use. •Apply with latent paint brush, set for 15 seconds, then rinse with cold water. •Consistently produces better contrast with less background staining than Sticky-Side Powder. •Excellent friction ridge detail results.