A composition for use in the production of metal traces and other metal components of printed circuit boards, wiring boards and the like. The composition includes the following components: (a) a metal powder, (b) a solder powder, (c) a polymer or a monomer which is polymerisable to yield a polymer, wherein the polymer is cross-likable under the action of a chemical cross-linking agent, and (d) a chemical cross-linking agent for the polymer, the cross-linking agent having fluxing properties and being unreactive with the polymer without catalysis. The polymer will generally be an epoxy resin and the cross-linking agent will generally be a polyacid. The composition preferably is one in which the metal powder and/or solder powder generates and/or has adhered thereto a catalyst for the cross-linking agent which is liberated on application of heat.