I give it 3 out 5 stars in terms of performance. The costs is not bad and usually runs about $20 to $30 U.S. Dollars depending on where you purchased this stone from. The first drawback I noticed was its size. I personally think that the perfect size for this stone would be similar to the size of a standard scotchbrite pad instead of its current size. In terms of performance it could be a little rougher in grit but it's much better than wet/dry sandpaper. I wore myself out using that method compared to this flattening stone. It does extremely well for medium and soft stones, but I would NOT recommend it for extremely hard stones such as jnats, cnats, black surgical or hard Arkansas oil stones. It simply doesn't have the cutting power which can be solved with a rougher grit and smaller size. Here's how to use the Norton flattening stone.
Step #1: draw a grid using pencil only on the stone that's to be flattened:
Step #2: Place the flattening stone with the diagonal ridges down on top of the surface that is to be flattened and work the stone back and forth under cool running water using firm pressure and circular motions. Think of trying to remove wax from your car:
Step #4: Dry with a clean cloth or paper towel and enjoy your results. Mine turned out great on the Norton 4K/8K combo stone. Here's the results I got on the 4K side:
And here's the results I got on the 8K side:
As far as flattening BBQ grill stones goes, I give this flattening stone a 3 out 5 star rating overall. It performed great and I got great results, but its size was a bit problematic. Here's what the grilling stones look like and you can get them at various BBQ supply stores, and stores such as Lowe's, Home Depot and Dollar tree also carries them. The large one I got at a restaurant supply store:
Here's how these stones work. Basically using water or biodegradable BBQ cleaner shown below, just simply place the stone on the cooking grate and work back and forth until your cooking surface is clean:
I like to use Weber's grill cleaner:
Or if I'm in a pinch, just plain old tap water will work with these stones:
Basically to flatten these stones, you just repeat the same process listed above:
And here's the results I got:
If I was asked if I would buy this stone again, then my answer would be NO. But if it had an 80 grit flattening surface and a smaller size such as a scotchbrite pad, then my answer would be a definite YES. There's always room for improvement.