Expanded Metal

Expanded metal is pretty slick stuff (not literally). It works as both classifier and as a sort of low profile set of riffles. It's often used over the top of moss to carry off the larger material and let the fines drop down, though I have heard that it can lower the effectiveness of moss when used under riffles, as the riffles press on the expanded metal and compress the moss.

One of the better applications of expanded metal over moss that I've seen is the Damn Fine Sluice. Basically, the long throat of the sluice lets material stratify some as it makes its way down the box, then the metal lets the larger material ride out the end as the fine gold and black sands settle into the moss. I haven't used one yet, but hope to if my finances ever get back in order. Heck, maybe they'll appreciate the mention here and send along a sample... ;)

You can pick up expanded metal at most hardware stores, but I'd likely hit the scrap yard first. Locally, I'd probably try Schnitzer Steel for expanded metal, punch plate, wire cloth/woven metal, etc, not just because I have a friend who works there, but because salvage yards have tons (literally) of metal scrap laying around that's just begging to be used in one project or another.

Online, you could check out any of the sponsors at right. I've also heard good things about McMaster-Carr, though the expanded metal is not easy to spot on their site. Once there, look bottom right under "Raw Materials and Springs". They also have a ton of other materials, metal and otherwise.

Send advertising inquiries to eathan {at} gmail {dot} com, trades welcome.