Kitaeji Maintenance 5

I was asked how Kitaeji reacts to natural Aoto.

I did not try only Aoto but I tried also other natural stones which I have in my collection. I do not have so many natural stones other than the finisher from Kyoto mines so I could try only 7 stones.

Aoto:
 

This is my favorite Aoto. The mine is unknown but it feels like a rare and very good  Akamonzen Aoto.
It has small red brown dots at the surface.

The Aoto is a middle stone. Though this Aoto is on the fine side of Aoto you can  still see some scratches. It does not destroy the Kitaeji pattern so it will be a very good middle stone or pre-finisher.

Now some finish stones which make semi mirror or mirror finish.
These are Mikawa Nagura (Mejiro), Tsushima Nagura (from mountain) and Translucent Arkansas.

 Mikawa Nagura Mejiro

 Big Tsushima Nagura (from mountain)

Translucent Arkansas

Now the results (they look almost same):

  Mikawa Nagura Mejiro Polish

Iy

 Tsushima Nagura (from mountain) Polish

Translucent Arkansas Polish

You can see that these finishing stones are not suited for Kitaeji polish.

Now back to some natural middle stones Iyo and Amakusa:

Iyo Stone (on hard side and porous)

Iyo Stone Polish

This Iyo stone was very very slow. But the result was not so bad as a middle stone.

But still not good enough compared to the 3 fingerstones I selected.

 Amakusa Stone

Amakusa Stone Polish

Amakusa was very slow too. Polish was similar to Iyo.

Last is my favorite middle stone Aizu:

 Aizu Stone

  Aizu Stone Polish

Aizu was the fastest of all stones tested here. You can see scratches but you can see the Kitaeji patterns too. Aizu is a very good middle stone but I can not find any Aizu now.

After every test and end of all the tests I used Hakka or Maruka fingerstone to get the Kitaeji pattern back.

Here the Shigefusa Kitaeji knife after all the tests:

 Maruka Fingerstone Polish

Hakka Fingerstone Finish

Conclusion:

Middle stones of Aoto, Amakusa, Iyo and Aizu does not destroy the Kitaeji patterns. They can be used if you do not care about scratch patterns.
But these middle stones are a bit brittle so I think you must enforce them with Japanese paper and Cashew lacquer if you want to use them as fingerstones.
And the finish is more bright and not so good as the finish with fingerstones I have selected.

Finishing stones which make semi mirror or mirror finsih destroy the Kitaeji patterns.  Mikawa Nagura, Tsushima Nagura and Translucent Arkansas are those stones.

If you want a nice Kasumi finish the results of this test is useful too.

Edit to add on 27th. July:

My friend Maxim at JNS has also blog about fingerstones:

Fingerstones

Kitaeji Maintenance 4

Here I want to show how Kitaeji react to synthetic stone.
I used my Arashiyama and polished the tip part of the Kitaeji.

 

I did not sharpen the edge. I just polished the Kitaeji because I wanted to know how the finish is.

Here are the results:

 

The Kitaeji patterns are gone where the stone polished the Kitaeji.

Before I used my fingerstone I wanted to know how Bar Keepers Friend (BKF) react to the worn Kitaeji. BKF was the only polish agent which was indifferent to Kitaeji patterns as you can see here:  Kitaeji Maintenance 2

Here the result:

  Some of the Kitaeji patterns are back but the contrast is very little.

 I used my Hakka fingerstone and in 1 min I had the Kitaeji patterns back.

Excuse me of the few scratches (you can see then if you click in the picture for full scale). I was in hurry and did not care about contamination.

Conclusion: 

From the 4 polishing agents only BKF is indifferent to Kitaeji patterns. 

Though weak BKF can get some Kitaeji patterns back. 

Synthetic Stone (Arashiyama) will destroy the Kitaeji pattern. 

But you can sharpen with synthetic stone and get the Kitaeji pattern back with Japanese Natural fingerstones.

Kitaeji Maintenace 3

Continued from Kitaeji Maintenance 2.

Case 3 Pikal:

Pikal is a polisher which is used in Japan.

I applied this polish at a part of the knife with a kitchen sponge.

1 min of polish and the Kitaeji pattern is almost gone.

Now maintenance with the Maruka fingerstone:

With experience I got better with the water/mud ratio. You will see it is almost all swarf and little mud.
After 1 or 2min the Kitaeji pattern is back:

Case 4 Chromium(III) oxide (Cr2O3):

This polisher is sold in Japan as "Aobo" which means blue stick.

Arrow is just indicating shadow of the "Aobo"

Cr2O3 polish with tissue paper

The Cr2O3 polish was quite slow. It took me 5 min and still the Kitaeji pattern was still visible.

I used the Hakka fingerstone to regain the Kitaeji pattern and the result is here:

Conclusion.

Polishing the Kitaeji with polishing agent which make mirror finish to soft iron will destroy the Kitaeji pattern.
I think some synthetic finishing stones does it too. (I did not do the test because I do not have fingerstones from synthetic finisher).

Regaining of the Kitaeji pattern is very easy with high grade natural fingerstones.

The contrast of the Kitaeji was:
Hakka>Maruka>Uchigomori

The uniformity of the finish was Uchigomori=Maruka>Hakka

I have tested more than 10 other natural fingerstones which I did not make any pictures. The 3 fingerstones in this test are the best 3 of the fingerstones I have tested so far.

These 3 fingerstones can be used to the Kasumi finish too to make nice haze.

Kitaeji Maintenance 2

What I did is polish part of my Kitaeji 180mm Petite with some polish.
These polish make mirror finish to very soft iron so in most cases the Kitaeji patterns are gone.

After the polish I used one or 2 of the finger stones and brought the Kitaeji pattern back.

Case 1 Mothers Mag & Aluminum Polish

You can see after the Mothers polish the Kitaeji pattern is gone.

Now I want to have the Kitaeji pattern back.
I used Uchigomori fingerstone with some water.

The mud or swarf is a bit thin for this Uchigomori finger stone. Swarf/mud ratio is high and indicate that this stone is a real "Sword Polish Grade" Uchigomori. In 1 or 2 min the Kitaeji pattern is back. But the contrast of the pattern is not so high.

Next I tried Hakka fingerstone:

The Hakka fingerstone makes much more mud.  After 1 minute or so I got much more contrast. With more contrast you get also the wide or broad lines.

Case 2 BKF:

I polished with BKF only 1 min or 2 min. The time maybe to short for the acid of BKF to react full with the steel. But still you can see that the Kitaeji got a bit brighter.

I used a Maruka fingerstone with water to eliminate the bright side caused with BKF.

 

I used the fingerstone for 1 to 2min. 

This Maruka fingerstone is the best of all 3 fingerstones in this test. It has high swarf/mud ratio and is very fast.

 The contrast of the Kitaeji pattern is in the middle of Hakka and Uchigomori.

More tests in part 3

Kitaeji Maintenance 1

 The maintenance of Kitaeji is very easy using Japanese natural finger stones.
I will write about it in part 2.

First some pictures of out of the box (OOTB) Kitaeji:

Kitaeji Gyuto 240mm

Kitaeji Santoku 180mm

Another Kitaeji Gyuto 240mm

The Kitaeji is made by carbon steel and very soft iron. You can read about it here:  Q&A with Iizuka san

 The patterns of Kitaeji carbon steel (see arrow) can be white or black. 

 It will depend on light. Carbon steel is more like a mirror and very soft iron has haze. If the blade reflect the light direct the carbon steel is white (white arrow). If it does not reflect the light direct the haze of very soft iron reflect more light and get brighter than the carbon steel (black arrow). 

 Kitaeji has also very narrow "hairlines".

 I do not know if I can show you it in this picture:

"Hairline" Kitaeji

It is the same "hairline the Kasumi finish has:

"Hairline" Kasumi

 You can see it much better in the Kasumi finish picture. But if you have the knife at hand you can feel the "hairlines" with finger or nail.

  Iizuka san does not tell me how he makes these hairline finish by hand. I think it is secrect.

  Other blacksmith who use machines make such hairlines with rotating steel brush. I do not have such machine so I will skip to make these hairlines.

  There are also some broader lines OOTB.

Broad Lines

 There are some broad lines which I indicated with white arrow. Iizuka san said these are "characters" of Kitaeji. The reason of these lines are not clear. Uneven diffusion of carbon froｍ carbon steel to soft iron or uneven distribution of boric acid powder can be the cause.

I tested 3 different finger stones.

Here the pictures of stones I made the finger stones:

Ohira Uchigomori Suita Sword Polish Grade

Nakayama (Maruka) Stone (a bit more orange than egg color)

Hakka (Finer an a bit harder than usual Hakka)

 Picture of the finger stones (Uchigomori and Hakka)

Left Hakka and right Uchigomori finger stones.

Continued to part 2