Isomalt hard coatings prepared from isomalt, a surfactant, and a coating binder provide good hard crunchy coating with good color without the usual stickiness problems typically associated with isomalt hard coating processes. Isomalt hard coatings prepared from isomalt, a surfactant, and a coating binder provide good hard crunchy coating with good color without the usual stickiness problems typically associated with isomalt hard coating processes. Gold and silver are recovered selectively such that gold and silver are separated from non-silver and non-gold material within the scrap. Gold and silver are recovered from scrap material using mixtures of acids, in some instances. The mixture comprises nitric acid and at least one supplemental acid, such as sulfuric acid or phosphoric acid. The amount of nitric acid within the mixture are relatively small compared to the amount of sulfuric acid or phosphoric acid within the mixture. The recovery of gold and silver using the acid mixtures are enhanced by transporting an electric current between an electrode and the gold and silver of the scrap material. Acid mixtures are used to recover silver from particular types of scrap materials, such as scrap material comprising silver metal and cadmium oxide and scrap material comprising silver metal and tungsten metal.Recubrimientos duros de isomalta preparados a partir de isomalta, un surfactante y un aglutinante de recubrimiento que proporcionan un recubrimiento duro y crujiente adecuado con buen color sin los problemas usuales de adherencia asociados, típicamente, con los procesos de recubrimiento duro de isomalta.
