Spanking beans to locate rocks

I have found a way to locate pebbles in beans that finds even the well camouflaged ones.   Most recipe books have you search for the rocks prior to soaking them.

I measure out and soak my legumes first.   Then I thinly spread a layer of them on a metal tray or cookie sheet, metal is important.   I then spank the back of the sheet with a wooden spatula.   If there is any rock in the tray, it will have a distinctive ping.   The soaked beans will have a dull sound.  

Sounds great! We'll try it. We serve rice, dal and vegetables at least once a day, and your method might be a great thing.

Photo of my favorite "Bean testing Tray".   The handles on both sides accentuates the rock ping.  Though a rock still sounds different than the beans if your holding on to the tray with your hand, not touching the tray with your hand makes it even more distinctive.

I test a handful of soaked beans at a time.