craftgrrl | Identifying Vintage Buttons

Hi. I recently bought about ten pounds of assorted vintage buttons and I'm hoping to Ebay them but I know that I'd probably get a lot more if I know how to tell which ones are bakelite, since those are worth more. I was wondering if anyone has some advice? I Google'd a bit and the only things I saw mentioned were to use 409 and Scrubbing Bubbles. Supposedly if you rub the button with a q-tip coated in either of those and it turns yellow, it's bakelite. The problem is, I don't use any sort of chemical cleaners in my home because they make me sick. So I'm wondering if there is any other way to identify them. It also seems like celluloid is really popular. Any tips on identifying those?

Any help would be greatly, greatly appreciated. Thanks a bunch.