Alba the Cat and more Sharpening Stone Experiments

This week we celebrated the fifth birthday of our cat. Alba is a beautiful feline that is part Siamese. She knew it was her birthday because she asked for lots of skritches and we were happy to oblige.  Alba was treated to several morsels of tuna fish.

My son Brandon received Alba as a gift when she was only a few weeks old. This is a photo of Alba the day she came into our home.

You'll be seeing more of Alba later..

Last week I received several questions regarding the Oven Dutch Cleanser (ODC) nagura and the red jasper stone from Jason who maintains My Peculiar Nature blog. Jason wanted to know if the five samples of ODC were a variety of different grits and if the red jasper would produce its own slurry, getting finer as I progressed with sharpening. Lets find out..

I took the Stanley No. 4 Plane blade to the DMT Extra Fine diamond stone and lapped the back and bevel. This would be a good starting reference to determine any changes in the scratch pattern.

Since I consider the red jasper a finishing hone I needed an intermediate stone after the diamond plate. The first stone I used to remove the diamond scratches was the vintage soft Arkansas stone. After about 100 strokes we start to see identifiable reflections of light on the back of the blade. Not quite a mirror finish but consistent haze.

Rudy at GSS provided five random samples of lithified tuff, or volcanic ash. I assumed all five were the same grit, but Jason pointed out that the five he received were of varying grits and texture. At first all five samples felt the same to me. Maybe it was because of the callouses on my fingers. However, after placing the tuff samples in a bucket of water, I was able to determine that two of the samples were course, two were medium course and one was extra fine. My friend did the same test with the same results. We have now confirmed and classified all five stones based on texture. I've already tried the course nagura stones on a previous experiment, but I didn't try the extra fine sample. All nagura stones are not the same and each nagura stone has a different effect on each sharpening stone. The key is to find the best match or pair for the maximum effect. The same can be true with tool steel and sharpening stones. Certain steels respond better on certain stones. Hence, my whetstone experiments.

Here is the extra fine ODC with a thick slurry on the red jasper. The extra fine ODC was easy to work with and didn't feel gritty. The jasper stone felt much different than with the course ODC nagura in previous tests.

After 100 strokes I start to see a faint mirror reflection on the back of the plane blade. The extra fine ODC works better than the course ODC from previous experiments.  

Next I wanted to try the Japanese Mikawa nagura stone for comparison. This nagura is extremely hard but also very fine. As you can see, it doesn't develop much of a slurry. However, the Mikawa activates the red jasper and produces an almost mirror finish after 100 strokes. This combination is very promising. We have used 200 strokes on the red jasper.

To confirm with a previous experiment, the DMT diamond plate as a nagura produced the best finish on the back of the blade after 100 strokes. The diamond plate and red jasper is the winning combination here. The total strokes on the jasper is now 300. What if I did 300 strokes with just the ODC? Or 300 strokes with the Mikawa? This isn't very scientific, is it? I still think the jasper and diamond plate works best. The ODC and Mikawa nagura will be saved for other sharpening stones. The down side to using the red jasper is that it does not produce its own slurry while working the back of the blade. This stone must be activated with another stone or diamond plate.

Last week I acquired a Thuringian whetstone on eBay and wanted to compare it with my other stones as a potential hone. I've read a lot about Thuringian stones and how prized they are especially by razor collectors. Thinking this stone was a fine finisher I started with 100 strokes. The stone quickly developed a thick black swarf and was aggressive at removing metal. However, when I turned the blade over I saw that my mirror finish was gone. Of course, this stone is 'yellow/green' and is the smoothest and most sought after Thuringians. This stone compares to my vintage Washita and is very quick to remove metal. Perhaps even better, faster.. This natural stone cuts extremely fast.. I'm impressed!

Needing to progress back to the mirror finish I grabbed the Ozuku Asagi Koppa Japanese whetstone and a recently acquired Uchigumori stone which is a finger stone used to develop the unique haze on the steel of Japanese swords. The Uchigumori stone comes from the Kyoto mine and has a grit between 3000 and 5000. It has super soft particles that will not scratch the blade. I'm going to try it as a nagura. It develops a thick slurry and feels much softer than the Koppa. The Koppa feels hard like glass.

After 150 strokes the mirror finish is starting to return. I'm really enjoying working with this Japanese natural stone. The texture and feedback are very desirable when working the blade. As I get closer to the point of sharpness, I gradually use less pressure on the blade. By doing so, I can see the wire edge break off the end of the blade and sit on the middle of the stone.  This particular stone works much better than the red jasper. The Koppa and Uchigumori stone might be the winning combination.

After about 1000 strokes the blade is now razor sharp without the use of a strop or honing compound. Its hard to see with my camera phone, but this blade has a mirror finish on back. The reflections are tools hanging on my wall. 

A better reflection of the bevel that has been sharpened to 30 degrees. This blade is ready to go to work.

Lately my sharpening experiences have become therapeutic.

Happy Birthday Alba!!