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Recommended procedure for soldering:
· 1. The steel surfaces must be clean and free of oxidation.
· 2. A rough surface improves adherence of the solder, so roughening with grinding wheel, file or coarse abrasive paper is recommended.
· 3. Use a phosphoric acid based flux. Hydrochloric acid based fluxes require neutralising after soldering as any remnant traces will be highly corrosive to the steel. Hydrochloric acid based fluxes are not recommended for soldering of stainless steels.
· 4. Flux should be applied with a brush, to only the area being soldered.
· 5. A large, hot iron is recommended. Use the same temperature as for carbon steel, but a longer time will be required because of stainless steel's low thermal conductivity.
· 6. Any type of solder can be used, but at least 50% tin is recommended. Solder with 60-70% tin and 30-40% lead has a better colour match and greater strength.