On 13 Jul, 20:25, wrote:
On Fri, 13 Jul 2007 18:49:43 GMT, "George"
wrote:

Glass,Metal oxide... ect.

So you use a softer one for wood than you would for metal? What's to
stop you just buying the hardest one and using it for everything? I

cost. And clogging

Sand is cheapest, but not a very good abrasive. Al oxide is the next
cheapest, and widely used. Good for wood and paint. But paint sticks
and clogs, so a more open abrasive is used, is with more open space
between the grains.


NT