Sunday, December 16, 2012

Tumble & Shine

Once I resolved the bails on this small series of simple pendants, it was time to fire and tumble them.  When silver clay is fired it does not come out looking shiny and metallic.  When I first tried metal clay I thought I was under-firing it because it kept coming out white.  Now I know that white is simply the fire-scale on the surface of the metal (below left).  It easily comes off with a brass brush, but leaves the silver sort of matte and in need of polishing.  A tumbler is a great way to polish up your pieces (not just metal clay) and it serves to help work-harden your pieces.  It also softens burrs that might be on your metal.  Tumblers range in price, I use the small inexpensive one above and can fit a number of pieces into it.  It's a simple tool, fill the barrel halfway with stainless steel shot (bought with the tumbler), a small amount of cleaning solution (see what your instructions recommend), place your pieces and fill with water just above the shot.  I run the tumbler for 2-3 hours depending on the degree of tumbling the pieces appear to need.  Below you can see the difference from the white fire-scale to the shine out of the tumbler.  A word of caution, soft materials such as pearls and turquoise may react badly with your cleaning solution, so know its compatibility and be sure precious metals are actually precious or the stainless steel shot may reveal more than a high shine!


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