Abstract: A special ink consists of water and a humectant. A reusable paper includes a surface darkened by a water-insoluble material and a coating covering the darkened surface. The coating is made of a material that scatters light when dry and that becomes at least translucent when wetted by water. If the special ink is used to print on the reusable paper, the print will be visible for a limited period of time (e.g., half an hour). By the end of that time period, however, the special ink will have evaporated and the print will have disappeared completely from the reusable paper. The special ink may be applied to the reusable paper by an inkjet printer. An inkjet cartridge for such a printer includes a casing filled with the special ink.

Abstract: A fingerprint detecting agent and a fingerprint detecting method using the agent, which can be used to detect latent fingerprints being in a wet condition, the fingerprint detecting agent includes a fixer containing silicone series compound, fluoride series compound, hydrocarbon series compound, animal or vegetable oil, higher fatty acid, or higher alcohol, and an arbitrary mixture thereof; a diluent containing polar soluent; a developer containing achromatic colored powder or chromatic colored powder. Latent fingerprints can be easily detected by spraying the fingerprint detecting agent; particularly, even if the latent fingerprints to be detected are in a wet condition, it is possible to detect them speedily and certainly.

Abstract: The present invention provides a transparent or colorless coating comprising a heat responsive material that increases in opacity when exposed to heat. An example of a heat responsive material is a silicate or a titanate. The present invention further provides a coating composition comprising a carrier and a heat responsive material. The coating can further include additives such as adhesion promoters, surface tension modifying agents, crosslinking agents, or plasticizers. The present invention further provides a method for creating a mark on a substrate comprising providing to the substrate the transparent coating to obtain a coated substrate and exposing a selected area of the coated substrate to heat, e.g., a laser, to create the mark. The present invention further provides substrates suitable for laser marking.

Abstract: The present invention provides a transparent coating comprising a resin and a heat responsive material that increases in opacity when exposed to heat. Preferably, the transparent coating is free or substantially free of a pigment or dye. An example of a heat responsive material is a carbohydrate. The present invention further provides a coating composition comprising a solvent, a resin, and a heat responsive material that increases in opacity when exposed to heat. The present invention further provides a method for creating a mark on a substrate comprising providing to the substrate the transparent coating to obtain a coated substrate and exposing a selected area of the coated substrate to heat to create the mark. The substrates can be marked with a laser.