GB957366A - Sonic cleaner - Google Patents

Abstract

A cleaning solution for removing tarnish from metal surfaces consists of water, thio urea, or thio-phosphoric acid and a non-ionic surfactant. The surfactant is suitably a condensate of ethylene oxide with polypropylene oxide. A powder composition consists of thio urea 30-85%, e.g. 65% meta-phosphoric acid 5-50%, e.g. 16%, surfactant 5-30%, e.g. 19%. An aqueous solution comprises 3-9 (e.g. 6) parts by wt. powder composition dissolved in 100 parts by wt. water (see Division C7).ALSO:The surfaces of metal articles are treated to clean and remove tarnish by immersing said articles in a solution comprised of water, thio urea, or thio-phosphoric acid and a non-ionic surfactant; and cavitating said solution by the application of sonic energy. The tarnish is formed of sulphide and oxide films and may be removed from the surface of silver, copper, and their alloys. The cleaning composition may be prepared in dry form when it contains thio urea, meta-phosphoric acid and a melting agent, which composition is dissolved in water preferably with heat applied and advantageously with sonic energy applied <FORM:0957366/C3/1> The wetting agent may be a detergent having surface active and detergent properties, e.g. non-ionic surfactants such as Pluronics. A mixed, uniform powder composition may consist of thio urea 30-85% (e.g. 65%), meta-phosphoric acid 5-50% (e.g. 16%), wetting agent 5-30% (e.g. 19%), Pluronic F-68 (for details see Specification). An aqueous solution comprises 3-9 (e.g. 6) parts by weight powder composition dissolved in 100 parts by weight water, and the action of this cleaning composition may be enhanced by mechanical agitation as provided by ultrasonic cavitation of the cleaning solution from sonic energy at a frequency and power amplitude sufficient to produce cavitation. The frequency is maintained above 10 kilocycles per second with a practical limit of 120 kilocycles per second, normally being at 20 kilocycles per second; and the power input advantageously may be 80 watts per gallon of aqueous solution. The solution may be cavitated by subjection to sonic energy for 1/2 -5 minutes, e.g. 1 minute, and cleaning is performed in sonic cleaning apparatus.