Sterling silver, in contact with skin oil, sweat and air, forms deposits that first appear as small dark dots; this tarnishing is material-typical and on non-sealed surfaces unavoidable. Pure cleaning cloth often does not suffice; more effective is wool soaked with silver-cleaning agent, which leaves a fine film easily removed with a soft cloth. Exactly this procedure is also applied by the Faber-Castell service, which for Graf von Faber-Castell generally works free of charge except for postage and shipping insurance. Sulphur-containing ambient air (e.g. industrial regions) considerably accelerates the deposit formation.