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I'd love to do something like this with my kid when they get a little older, but am always hesitant on the health risks on grinding the mirror. Can anyone shed

I'd love to do something like this with my kid when they get a little older, but am always hesitant on the health risks on grinding the mirror. Can anyone shed light on the health risks if any?

tzs 6y ago
You grind a mirror by hand by taking two glass discs, and rubbing one against the other with a slurry made of abrasive grit and water between them, with the length and direction of your strokes determining which disc becomes your concave mirror. You start with large grit and work down to smaller grits as you get closer and closer to the desired final mirror curve. The large grits seem unlikely to become aerosolized during this. The finer grits are pretty small (a few microns) so probably could become suspended in air but because you grind wet, not dry, this probably isn't likely. Just work in a place with good air circulation and it should be OK. There's also the glass particles that get removed to consider. I'd expect that they just end up in the abrasive slurry. This all assumes you are hand grinding. If you use some kind of power tool that goes a lot faster than the sedate processes that is hand grinding, all bets are off. There might be other ways things could get in the air. You can deal with all of that by wearing a respirator like you would for painting or sanding (once they become available again...).
- londons_explore 6y ago
  If I were giving this to my child to do, I would give the child gloves, instruct them not to eat the slurry, and make sure they wash everything each day. If they break any of the rules, the health risks are minor.
  - AstralStorm 6y ago
    Well, to remove the final risk you can wear glasses and a dust mask.
VLM 6y ago
Interesting scaling problem: A kid should probably start out making a 6 inch mirror which only weighs maybe a pound. But mass goes up by a factor of a cube with diameter... the linked article 15 inch mirror blank is likely 75 to 100 pounds? You can buy special thinner blanks but it gets to the point where in a wet slippy fingers situation it doesn't matter all that much if 60 pounds or 80 pounds lands on your toe when you drop it. Something the other responder didn't mention about wet grinding is after you finish with a coarser grit, perhaps 200 grit, you have to clean the mirror and the local environment VERY completely or else when you switch to finer 400 grit even one tiny grain of 200 grit will ruin and scratch up the attempt at a 400 grit polish. So its kind of self-fixing in that if you're not screwing up, there will never be aerosolized grit because your working area will be very clean indeed. Its a very clean hobby, compared to most.
tejtm 6y ago
It is really easy, keeping glass wet (with water) while grinding & polishing keeps it in a slurry so no airborne particles to give you silicosis.

I'd love to do something like this with my kid when they get a little older, but am always hesitant on the health risks on grinding the mirror. Can anyone shed light on the health risks if any?

tzs 6y ago

You grind a mirror by hand by taking two glass discs, and rubbing one against the other with a slurry made of abrasive grit and water between them, with the length and direction of your strokes determining which disc becomes your concave mirror. You start with large grit and work down to smaller grits as you get closer and closer to the desired final mirror curve. The large grits seem unlikely to become aerosolized during this. The finer grits are pretty small (a few microns) so probably could become suspended in air but because you grind wet, not dry, this probably isn't likely. Just work in a place with good air circulation and it should be OK. There's also the glass particles that get removed to consider. I'd expect that they just end up in the abrasive slurry. This all assumes you are hand grinding. If you use some kind of power tool that goes a lot faster than the sedate processes that is hand grinding, all bets are off. There might be other ways things could get in the air. You can deal with all of that by wearing a respirator like you would for painting or sanding (once they become available again...).

londons_explore 6y ago
If I were giving this to my child to do, I would give the child gloves, instruct them not to eat the slurry, and make sure they wash everything each day. If they break any of the rules, the health risks are minor.
- AstralStorm 6y ago
  Well, to remove the final risk you can wear glasses and a dust mask.

VLM 6y ago

Interesting scaling problem: A kid should probably start out making a 6 inch mirror which only weighs maybe a pound. But mass goes up by a factor of a cube with diameter... the linked article 15 inch mirror blank is likely 75 to 100 pounds? You can buy special thinner blanks but it gets to the point where in a wet slippy fingers situation it doesn't matter all that much if 60 pounds or 80 pounds lands on your toe when you drop it. Something the other responder didn't mention about wet grinding is after you finish with a coarser grit, perhaps 200 grit, you have to clean the mirror and the local environment VERY completely or else when you switch to finer 400 grit even one tiny grain of 200 grit will ruin and scratch up the attempt at a 400 grit polish. So its kind of self-fixing in that if you're not screwing up, there will never be aerosolized grit because your working area will be very clean indeed. Its a very clean hobby, compared to most.

tejtm 6y ago

It is really easy, keeping glass wet (with water) while grinding & polishing keeps it in a slurry so no airborne particles to give you silicosis.