I have a 9x12" granite surface plate which I usually exclusively as a level surface for wet-sanding/lapping parts after I have milled them in my TAIG. I'm curious - any harm in leaving the granite plate submerged in water for hours/days?

I wet-send in a large tupperware bin with surface plate submerged in water. I used to drain the water everytime, but it would be nice if I could just leave the water in it...

Thanks.

Granite is one of the more impermeable rocks, as long as you dont let the water freeze Id be surprised if you managed to damage the plate with water. Watchout for the abrasive slurry that you are making in the tank tho, that probably will cause the surface to wear concave.

Think about the mountains of the English Lake District, granite thats been there in the wet for thousands of years ;)

Dave

If it's a very accurate surface plate, I wouldn't use it like that. Not when I can get a cheap 9 x 12 x 2 B-grade plate from ENCO for $15. on sale right now. I'd be more concerned about the abrasive than the water.

If it's a very accurate surface plate, I wouldn't use it like that. Not when I can get a cheap 9 x 12 x 2 B-grade plate from ENCO for $15. on sale right now. I'd be more concerned about the abrasive than the water.

That's exactly what it is - one of the cheapies from Enco with free shipping. Perfect for lapping / sanding...

Water won't hurt it, the grit will. I know this from our grinding department at work. The grit in the air settles on the granite, and the sliding of parts, as the lads check their work, eventually wears a hollow into the granite. But good surface plates are reasonably priced, so we accept the life span.