66 B, if you just want to clear coat an already powder coated surface, a good rub down with a new Scotchbrite pad will give you the roughness needed for the powder to adhere. Make sure you don't leave any finger prints or they'll show up too. :-D
If you're wanting to clear bare metal, any glass bead, aluminum oxide or similar media will work just fine. I usually use Black Beauty black slag in a fine grit; though it costs a little more than blasting sand, it lasts a LOT longer (3-4 times), won't give you silicosis, and cuts much faster.
I'm always happy to answer questions. Keep them coming!
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It just dawned on me I failed to announce the July Special on FBBO. Sorry for the late notice guys.
It's 20% off on any job over $100.00, and there's still a few days to get the parts here to take advantage of the sale. (I'll cut a little slack on the arrival date since I was extremely late in telling ya'll about it.)