Apologies if there is the 'teaching people to suck eggs' thing. It is certainly not intended!
However, I recall 2 quite important references. One is the freebie of the Holzapffel books and apart from a seemingly myriad of information, describe different abrasive and how to sort out- what you create. Great stuff but there is the classic Amateurs Lathe by Sparey who, if my memory is holding out, described using powdered brick dust at some point or other.
Both are well worth a place in anyone's shelf.