What size grit do I use to sandblast?

[Nancy Mc]

What grit silicon Carbide is best for sandblasting. 80 grit or 120? Just want to change surface texture and do some of Brock Craig's techniques on irid. Sorry if this is an old question.

[Brock]

For your purposes, I'd go with 120. If you're gonna do the double irid technique, make sure you've got Aluminum Oxide. Silicon Carbide, while a superior grit for most techniques, is a DEFINITE No NO for double irid.

[Tom White]

Brock, would you please explain why you need aluminum oxide instead of silicon carbide for double irid technique? Silicon carbide is all I have on hand now.

Best wishes,
Tom in Texas

[Brock]

Brock, would you please explain why you need aluminum oxide instead of silicon carbide for double irid technique? Silicon carbide is all I have on hand now.

Best wishes,
Tom in Texas

I don't know if we ever got a definitive answer, but Tony Smith, Nikki O'Neill, and Steve Immerman investigated it, and I believe the consensus was, that the SiC fractured the glass leading to many tiny bubbles, that look crappy (technical term). It looks gray, like it wasn't cleaned properly, even if you scrub it thoroughly.

When using AlOx, a good cleaning results in a nice black colour, not gray.

Maybe one or more of the above will chime in. Brock

[Tom White]

Guess I will have to get some 120 grit Al2O3 to try the double irid technique.

Best wishes,
Tom in Texas

[Tony Smith]

Brock described it accurately. The SiC particle is very hard and very sharp and when it impacts the glass it creates microfractures in the glass which trap air during fusing and make it appear grey or cloudy (or dirty). Although some people have had "mixed" success using SiC with this technique, a number of us have had unacceptable results regardless of how much scrubbing and cleaning we did prior to fusing the mating pieces together.

Tony

[Jeri D]

Can you use beach sand to blast.? I found someone to bring over their equipment( I have the compressor) and he has "slag" and sand. I want to blast off fiberpaper stuck to the bottom of a 15x15x1/2 end tabletop.

[Brock]

Can you use beach sand to blast.? I found someone to bring over their equipment( I have the compressor) and he has "slag" and sand. I want to blast off fiberpaper stuck to the bottom of a 15x15x1/2 end tabletop.

Yup, but, ya gotta screen it Jeri, otherwise it's like throwing rocks at glass.
Hmmm, is your table glass? I'd screen it anyway, just to get some consistency in particle size. Brock

[Jeri D]

yup,glass strips ,kind of like a flat marty piece.
What size screen to use?
Ya know what was weird, the top, under the heat, the French white strips seemed to bleed out , not stay concise like the back side( maybe now my front!) I thought white was the hardest! Could it be the french thinks of itself as a ripe camembert
Jeri
not a bon vivant but forever a foodie

[Brock]

yup,glass strips ,kind of like a flat marty piece.
What size screen to use?
Ya know what was weird, the top, under the heat, the French white strips seemed to bleed out , not stay concise like the back side( maybe now my front!) I thought white was the hardest! Could it be the french thinks of itself as a ripe camembert
Jeri
not a bon vivant but forever a foodie

Any size screen, you're after consistency, not any precise particle size. That plastic mesh for doors would work. Sounds like you got some of that rare Saturday glass, Camenfritolla.

[Paul Tarlow]

I believe the health hazard with using sand is that a good deal of silica is put into the air.

- Paul

Can you use beach sand to blast.? I found someone to bring over their equipment( I have the compressor) and he has "slag" and sand. I want to blast off fiberpaper stuck to the bottom of a 15x15x1/2 end tabletop.

[Kevin Midgley]

Beach sand is dull, not sharp for blasting. The dust is incredible. It can be used but it isn't a good idea in terms of health and working time which is much slower than using a commercial abrasive like aluminum oxide.
Kevin

[Jeri D]

Thanks for your replies. I am hoping to find a booth, but the few here are blasters for boats or machine parts. No glass blasting done on the island!
J

[Tony Smith]

You can always make one from a cardboard box or rubbermaid tub and a piece of clear glass for the window. The main things you'll need are a shopvac to remove the glass dust and a pair of rubber gloves to protect your skin & nails. The hardest time you'll have is holding up the gun (if you go with a siphon tube in a bucket) or the blaster if you use one of the portable blasters. There are some low cost pressure pots available , but "low cost" is relative. While you can buy the basic pressure pot for about $100, you really should have a cabinet to work in just for personal protection. This is strictly a personal opinion, but having blasted in the open before, I think it's the safe approach. And if you're going to buy a cabinet, they all come with a built-in siphon blaster anyway. If you have compressed air available, you should try starting with just the siphon blaster. I realize that this is confusing, but it's all a matter of personal choicesand investments, and they are always confusing.

I've updated my website to include the "Sandblasting on a Budget" information that I presented at WGW and you can find that at http://www.amsmith.com/sandblasting/inf ... ginfo.html

I have more information on pressure pots that I'll try to get out later this week.

Tony

[lissa]

I am wanting to sandblast the surface of pieces and then firepolish them back to full gloss. I am looking for Aluminum oxide grit and have a few questions. Do I want white or brown, and how fine do I need to get? Someone told me 180 should be o.k., but that seems a bit coarse if I want to get it back to full gloss. Lastly, where do you buy it? I only want 50# of it and am having a hard time finding a source online.

lissa.

[Tony Smith]

I am wanting to sandblast the surface of pieces and then firepolish them back to full gloss. I am looking for Aluminum oxide grit and have a few questions. Do I want white or brown, and how fine do I need to get? Someone told me 180 should be o.k., but that seems a bit coarse if I want to get it back to full gloss. Lastly, where do you buy it? I only want 50# of it and am having a hard time finding a source online.

lissa.

You want brown aluminum oxide. Try
3R Mineral & Manufacturing
6911 Parke East Blvd, Tampa, FL 33610
(813) 740-2440
http://3rmineral.com/glassetching.htm

You won't be sandblasting to get your shine back, so the coarseness of the grit is almost irrelevant. You need to firepolish to get the shine back. 120 grit is a good, all-purpose grit... but anything 120 to 180 will work.

Tony

[lissa]

Thanks Tony, that is good to know. After we slice our murrine on the tile saw we always take them to 400 grit on the lap wheel prior to fire polishing to get the cleanest gloss, but if 120 or 180 works with sandblasting that's great! A more versatile grit.

By the way, the sandblasting section on your site is great, what a nice service to give.

Thanks for your help.

lissa.

[Tony Smith]

Thanks Tony, that is good to know. After we slice our murrine on the tile saw we always take them to 400 grit on the lap wheel prior to fire polishing to get the cleanest gloss, but if 120 or 180 works with sandblasting that's great! A more versatile grit.

By the way, the sandblasting section on your site is great, what a nice service to give.

Thanks for your help.

lissa.

Yeah, nobody that I know of blasts with anything higher than 200 grit. Above that, the particles are so small that they have almost no effect on the glass.

You're welcome.

Tony