Garnet vs crushed glass

[bcguy]

My task is abrasive blast below waterline steel sailboat coated with MC Tar about 10 yrs ago. Coarse crushed glass is fairly cheap relative to Garnet. Just wondering if anyone has experience with abrasives and my best bet. Thanks...

[model 10]

Beside the point I'm sure, but you can get grit that has nickel in it. I had an aircraft steel tube fuselage blasted with this stuff. The idea was the inpinged nickel gave some corrosion protection

[hellosailor]

Garnet is harder than glass, but I'd guess the glass is still going to shred the tar and if you need more glass than you would need garnet, the glass still would be cheaper. If disposal raises hazmat problems, there are also systems that use crushed dry ice, which leaves no extra "blasting" material in the residue as it evaporates after use. That should also make the tar more brittle and easier to get off. Something to check with local suppliers.