To harden sterling silver, heat it to 600°F (316°C) for 30–50 minutes in a kiln or furnace. Air-cool the sterling silver before pickling. The hardness will be equal to the hardness achieved by cold-working it to a 50% reduction (or ¾-hard). If you want to make your sterling silver harder than ¾-hard, you must physically reduce the cross-sectional area using the chart below.
|Rockwell Hardness||Common Term||Reduction in Cross-Sectional Area|
|Fine Silver||Sterling Silver||Wire||Sheet|
Example: If you start with a dead-soft wire and reduce the cross-sectional area by drawing it down 50%, your material will become ¾-hard.