Saturday, May 25, 2013

Heat Hardening Argentium Sterling

Typically jewelers and other metalsmiths harden metal via working it. Hammering, twisting, or bending have the effect of compressing the atoms within grains, relocating defects to grain boundaries, and generally hardening the metal.

It's also possible to use heat to harden metals, in a process called precipitation hardening, whereby the composition of tiny areas within the metal shift as the different components of an alloy redistribute due to mobility of the atoms. The procedure for heat hardening conventional silver is well known, but leads to a relatively small amount of hardening and a correspondingly deep firescale that is hard to remove. However, using heat hardening for Argentium results in a significant hardening, up to twice that of unhardened sterling, with NO firescale, while also enhancing the tarnish resistance of the Argentium surface.

Ronda Coryell from Jewelry Studies International shared this video of the hardening process using a household oven at lower temperature for a longer time. I use my handy metal clay kiln with a schedule of full ramp to 570ºF kiln and hold for two hours.

Find further information about heat hardening Argentium and the User Guide for Original Argentium on the Argentium Guild website.