[mura_gadi (Steve)]

Hello,

The shatter caused by silicon carbide is greater than that caused by aluminium oxide at the same grit. The fractured surface material generated by aluminium oxide has smaller pits, fractures, smaller loosened bits of material etc to clean away. That makes progressing between grits a little friendlier and gives a smoother final finish than Sic at the same grit. Ideally if you had a lot of glass to hog, you'd go 80/120 silicon carbide for fast hogging, then 180-220 aluminium oxide to rough figure/figured focal length onwards.

"Keep in mind that silicon carbide leaves pits about three times deeper than aluminum oxide" from The Joy of Mirror Making - Mel Bartels.

Hobby Gem shops and lapidary clubs for polishes and grits etc... a quick google will give you a lot providers.

Kemet industries Sydney, or any high end polishing/lapping company really in your area will have them.



Luckily NSW is very good for options.
Steve
Ps. At 5 and 9 micron, see if you can find microgrits and I would not suggest spending extra on "optical grade" material. Get microgrits or check to see if your oxides need a wash prior to use.

Pps. Keep an eye out for zirconium oxide over rouge if you can find it for later.