If the actual chips in bulk look anything like my samples, I don't think any oiling is necessary, and may actually do harm (remember
this post?) BTW, the purpose of oiling isn't to get rid of dust (think about what would happen if you added some oil to a little pile of dust--now you've got
yucky sticky dust paste). The purpose of oiling is to get some oil absorbed into the clay, which I believe reduces the surface opacity/reflectivity and makes the chip color appear darker/deeper (think about what your shirt or paper napkin looks like when you drip some oil onto it).
