Cleaning Pastels

I have a bunch of pastels that I hadn't used in some years and because I didn't take care of them, many are covered in dust from other pastels and each looks dead and gray.  I read somewhere that you can clean your pastels by filling a cup or some container with rice, inserting the pastels into the rice and giving it a few shakes (with a lid on it, so I learned).  That worked pretty good, but it is a little inconvenient because you have to clean your pastels a few at a time, and my pastels tend to always be dirty.

So, my mind racing, I thought of a way of making a kind of tumbler with a motor that would allow for more rice and many more pastels.  But making something like this is a little daunting for me.  Then I remembered that about 20 or so years ago while vacationing with my family at Cape May, I found in some small shop near the beach a Lortone Model 3A rock tumbler, which they still sell.  One of my many interests is rock collecting and lapidary.  I've done neither, but finding the tumbler sparked my imagination and so I had to have it.

Back to the present.  I figured I'd try using the tumbler by filling it with the rice and placing in it a few pastels.  I let it go for a few minutes and it worked.  The harder pastels cleaned well, but the softer pastels not so much.  Part of the problem, I think, was that I was using the old rice I was using when cleaning them in a container.