For the application of aqueous reagents, contact transfer is an alternative to dipping or spraying. The Derivapress, Fig. 16, uses a simple press, that opens and closes like a book, to bring the layer into contact with a transfer pad impregnated with the reagent solution. After brief contact, the press is opened and excess reagent is reads or bed by the transfer pad leaving a dry layer evenly impregnated with reagent. In early versions of this device, the transfer pad was made from an absorptive open-cell polyurethane foam material. A different or modified material is possibly used in the current version. Reagent solutions that do not wet the layer completely will not transfer homogeneously by this method.