The hardness ratings you may know of are from different sources and, on our opinion, are not accurate and there is no true way to measure the hardness of a porous organic material. The tool used to get these numbers you see below is from a device made to measure the hardness of plastic materials. But the numbers we have below were not measured by Kamuitips.com or Kamui™ Japan.
Kamui™ Soft - 69.6