Thread: Flatten an extremely hard stone

Hello,

How to flatten an extremely hard stone?

I have just found a very old "La Lune" stone with a slightly uneven surface in places. I have just used all the tools at my disposal (sander, sandpaper, synthetic stone, cheap diamond stone, etc.) to sand the surface and I can't do it!

Anyone have an idea on how I can sand this stone with accessible DIY means?

Best regards

I would use course sic and work up through the grits until I reached the grit i wanted for it.

A grid with pencil, (prefer sharpy because it doesn't wash off) and lots of elbow grease and patience.

I get silicon powder from Lee Hardware but loads of places sell it, its not uncommon.

Just my humble opinion

Yeah, silicon carbide powder works well on a flat surface like a piece of glass or a marble tile, some people even use a cooky sheet from the thrift store on a cement floor. I go up to 500 and then finish with wet dry sand paper. If you don't want to buy the SIC powder there's no reason you cant do it all with wet/dry. (though you might go through a bunch of it depending on how warn the stone is)

Ditto the above. I get mine on eBay. This is a link to the seller's store that I have had good luck with.

https://www.ebay.com/str/rockbottoml...mis&media=COPY


They have a variety of sizes of grit and packages. If a stone is really wavy you might want some really coarse. I have 16 which are like pebbles almost; coffee grounds really. That works really fast but leaves lots of deep scratches so be prepared to work up and careful that you don't get too heavy handed or you may have to remove more than you want to get all the scratches out and make it smooth. I find I use a lot of 80 and 220 but before long you will figure out what to get big packages of and what to get small. If you get something in the middle to start you will be safe but you don't want to run out in before you finish because that can be anticlimactic. " Whomp, whomp, whomp-whomp."

I have done some very hard, very uneven hones underwater on a Diamond plate. It does take a toll on the Diamond plate. I will order SiC for my next hard hone flattening. My current setup is great for softer hones.

Moonstone is not that hard . Around 6 on the Mohs hardness scale.
SiC should kill it but any Corundum sandpaper should also be harder. Maybe a belt sander might help. Wear a mask tho.

Originally Posted by tintin

Yeah, silicon carbide powder works well on a flat surface like a piece of glass or a marble tile, some people even use a cooky sheet from the thrift store on a cement floor. I go up to 500 and then finish with wet dry sand paper. If you don't want to buy the SIC powder there's no reason you cant do it all with wet/dry. (though you might go through a bunch of it depending on how warn the stone is)

How do you use thrift strore cooky papers? Why not from the supermarket?

What i meant was an Aluminum cookie sheet/pan. I suppose you could buy a new one if you wanted. I would think that something harder would be more precise though.

Flattening a hard rock takes a lot of elbow grease. One thing I have foun is that buying good quality sandpaper really makes a difference.

Ark's are about the hardest I've encountered, and still, sandpaper worked just fine.

But if your working a hone with severe unevenness/damage, I'd recommend the loose SIC grits in 80 and 220. Paper should work once you've got it flat again.