#18 Mikawa Shiro Tenjyou Nagura

For sure a knife shaped and sized Mikawa nagura. This stone will make fast middle work of most steels replacing the 2k to 4k work that your synthetics, while leaving shallower scratch patterns for your finishing stones to deal with. There are some gas voids as you can see in the photos but these can be cleaned up as they appear.
Almost too thick for the width and length. The ends are fairly square so it will fit into a stone holder but for sure a monumental chunk of white shiro nagura.

I have a straight razor pictured with the stone for size and scale, and there is no reason why this stone cannot be used for honing razors, it is just that the scale is geared for knives.

This shiro white nagura makes an excellent middle stone, inserted between a bevel set and the final finishing stones, or it can serve as a giant nagura rubbing stone. It will remove metal from the hardest razors leaving a more polished surface.

I found that these base stone nagura are easier to use if you soak them for 1 to 2 minutes so the hydration becomes consistent. Splashing clear water as you go along will keep them cutting.

Becoming very scarce in this size, I do not know how long I can continue to source them from my nagura miner who keeps telling me that these will be the last he will every see. He is old so I believe him. These and all of my other bench size Mikawa nagura do not have Asano ink stamps or any other attributions because I circumvented the stones before Sakamoto-san the owner of the Asano stamps had a chance to make his a bid.

The stone (toishi) has been lapped perfectly flat and the corners and edges beveled unless otherwise noted.  All of my stones come with a money back guarantee minus the return shipping.
 
Hardness                   6+
Particle Size               9+
Speed/Cutting           9++