Here are some comparisons of SPG's and ABS of a few stones of mine. They were not run in a laboratory, I just made do with what I had at home. I am pretty close on the numbers though and I think it's interesting how the stones differ.
The Washita's are vintage stones that had been degreased. I believe they are pretty clean though as I had another soft Ark that I thought had never been used and I found out different when I dried it in the oven and oil came to the surface. None of the Washita's did that and Dan's stones used here have never been used with oil.
My absorption numbers could easily be off a tenth or two as my scale isn't that fine and it's hard with such a small sized sample but still trends are apparent.
Washita 1- SPG -2.289 - ABS 1.0
Washita 2- SPG- 2.268 - ABS 1.1
Dan's SFT- SPG- 2.321 - ABS 1.9
Dans HRD- SPG -2.466 - ABS 0.8
Dan's BLK- SPG- 2.700 - ABS 0.2
The Washita's are vintage stones that had been degreased. I believe they are pretty clean though as I had another soft Ark that I thought had never been used and I found out different when I dried it in the oven and oil came to the surface. None of the Washita's did that and Dan's stones used here have never been used with oil.
My absorption numbers could easily be off a tenth or two as my scale isn't that fine and it's hard with such a small sized sample but still trends are apparent.
Washita 1- SPG -2.289 - ABS 1.0
Washita 2- SPG- 2.268 - ABS 1.1
Dan's SFT- SPG- 2.321 - ABS 1.9
Dans HRD- SPG -2.466 - ABS 0.8
Dan's BLK- SPG- 2.700 - ABS 0.2