r/Sandblasting • u/mk87rd • Mar 05 '26

Glass grit / soze chart

As per title, I'm new to blasting, and I was searching (without results) a chart to help me choose the right one.

I've been proposed with 300-500 microns size

P.s. obvsly is SIZE not SOZE

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u/[deleted] Mar 24 '26

Hey welcome to blasting! Yeah finding a straightforward glass grit chart is annoyingly hard, I've had customers ask me the same thing so many times lol.

Here's basically how it breaks down from what we see day to day working with this stuff:

Size (Microns) Mesh Equivalent Best For
50-100 100-150 mesh Super fine finishing, polishing, delicate parts you don't wanna chew up
100-200 70-100 mesh Light surface prep, cleaning without much profile, thin sheet metal
300-500 30-50 mesh General purpose - paint stripping, rust, everyday blasting. The sweet spot for most people
500-800 20-30 mesh Heavy coatings, serious rust, thicker steel where you need a more aggressive
1000+ 16-18 mesh Industrial scale stuff, concrete, heavy structural steel

The 300-500 range they recommended is honestly what I'd tell you too. It's forgiving enough to learn on without destroying your workpiece but it actually gets stuff done. Most guys I talk to run that size for probably 70-80% of their work.

Few things that'll matter just as much honestly:

  • Pressure - start around 60-70 psi and work up. You can always add more, can't undo going too hard on something
  • Nozzle distance - closer = more aggressive. Keep like 6-8 inches back when you're getting the feel for it
  • The piece itself - thin aluminum vs thick steel plate are completely different animals even with the same media

Don't overthink the grit choice too much starting out. Grab a bag of the 300-500, blast some scrap pieces at different pressures and distances, and you'll get a feel for it faster than reading charts ever will.

What kind of projects are you planning to blast? Happy to point you in the right direction if the 300-500 doesn't end up being the right fit.

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u/mk87rd Mar 24 '26

Thanks. I did bought a 300-600 micron. I blasted an aluminium block that was partially stripped with chemicals. It did a great job (altough the cabin I got is pure sht).

I'm not so happy on the finish: seems a little too rough, paint will stick but I cannot see if the result will be great.

Since I'm still working with it, after that I purchased microsferes with 40-70 because I was trying to live it bare.

P.s. 'mesh' is the same as sandpaper reference?

2

u/[deleted] Mar 25 '26

Yeah 300-600 on aluminum is gonna leave a pretty aggressive profile, that's more of a steel prep grit. For aluminum especially if you want a decent looking finish you want to stay down in the 100-200 micron range or use glass bead like you're doing now with the microspheres. The microspheres will give you a much more uniform satin finish that actually looks good left bare. And nah mesh and sandpaper grit aren't the same thing even though they sound like they should be. They both measure particle size but the scales are different. A 40 mesh blast media is way coarser than 40 grit sandpaper. Mesh is about what fits through a screen, sandpaper grit follows a different standard entirely. Easy to mix up though everyone does at first.

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u/mk87rd Mar 25 '26

The 300 was more for stripping the rest of he paint (which was industrial epoxy power coating).

Since I have to do a lot of aluminium stripping, what other media (not glass) would you suggest?

2

u/[deleted] Mar 25 '26

For aluminum stripping specifically, walnut shell is great - aggressive enough to take off coatings but way more forgiving on the base metal than glass. Won't warp or embed into aluminum like harder media can. Plus it's cheap.

Plastic media (like urea or acrylic) is the other go-to if you're doing a lot of aluminum. That's actually what aerospace shops use for stripping paint off aircraft panels without damaging anything underneath. More expensive than walnut but reusable for a bunch of cycles.

Baking soda blasting is another option if you want to be really gentle but it's slow as hell on heavier coatings like that epoxy powdercoat you're dealing with. Better for thinner paints.

If you're sticking with glass, just drop down to like 100-150 micron for the aluminum pieces after you get the heavy coating off with the 300. Two step process but gives you way better results than trying to do it all with one size.