How to detarmine stone hardness

[Brian Dormer]

I have inherited a number of tools from my uncle - who was a woodcarver for most of his life. Some of the stones (Arkansas Hard) are marked. Others are not. I'm certain he knew what was what - but unless it's marked - I don't have a clue.

There is also a RED diamond plate (I think RED is FINE/HARD).

Is there any way to determine what hardness these are? I have about 8-10 stones to identify.

Also - is there a general rule as to whether you use water or oil on a given stone (or the diamond plate).

[j.e.mike tobey]

Take some steel to them. The finer the scratches, the "harder" the stone.mt

[Bob Barkto]

The diamond stones should be used with water or used dry. Water is better IMO as it helps keep the stone clean and keeps the dust down. I add a drop of dish soap too.

For the others... a little testing might determine what was used on them.
A drop of water will bead up real quick on an oily stone. If it is a water stone the water will soak in quickly on coarser stones.
Smell them! Sometimes the oily odor will remain.
Warm them and place them on an absorbent cloth and see if they leave an oily stain.
Water stones are generally pretty soft and can be scratched easily with a hard object. You should see a powdery trail in the scratch. Some of the newer water stones like the Norton and Shapton stones might be too hard to tell by the scratch test.

Oil stones can be used with water. Use a lot. A little drop of dish soap helps too.
If the oil stones are oily continue with oil or clean them before switching to water.

Water stones, like Japanese water stones, Belgians, Nortons, Shaptons and the old razor stones must always be used with water only. Oil will ruin them.

For determining the relative fineness... use them! The diamond stone is probably a fine grit, about 600. It depends on who made it tho.

Can you post a picture?