ForMatter/Processes/joining/Jewelry Soldering — Hard Tier
proc_soldering_jewelry_hard

Jewelry Soldering — Hard Tier

joining · hard solder, high-temperature jewelry solder, first-fit solder

The highest-melting tier of jewelry solder — the one used first in a multi-step build because every later soldering operation has to stay below its melting point. Each metal family has its own solder hierarchy: silver hard / medium / easy, gold hard / medium / easy / repair, platinum its own thing. The whole system exists so a jeweler can build a ring with a dozen joins without melting any of the earlier ones.

Filler-metal alloy with melt range 740–815 °C for sterling silver hard solder (~75% Ag balance Cu / Zn); 750–800 °C for 18k yellow gold hard solder; 1100 °C+ for platinum hard solder. Capillary action draws solder into the joint at temperature; flux (paste boric / fluoride for silver, fluoride for gold, none typically for platinum) prevents oxide formation. Joint strength approaches 90% of base-metal strength when properly executed.

Scale & Tolerance

  • scale (mm)1 – 100
  • tolerance (mm)0.1
  • skillintermediate — temperature reading, flux placement, and timing all critical
  • costlow

Equipment

  • school_shoptorch (acetylene-air or oxy-propane for silver / gold; oxy-hydrogen for platinum), soldering board, third hand, solder pick, flux

Environmental

  • energy_uselow (torch only)
  • waste_streamspent flux, oxide pickle
  • consumablessolder, flux, pickle

Citations