Hira polishing - Discussion on how you approach it

[KasumiJLA]

Hi all

I made a little demo to a friend who was wondering how I worked the hira to prepare the surface. So I thought it might be of interest to some of you here.

I have currently three methods of doing it: good old sandpaper, this version on the side of the whetstone and obviously flat on the stone. There are positives and negatives about this method I use. Here is a summary:


Positive
- No slurry to manage, so you can push the mirror finish quite high with synthetics. I can go up to 12k and everything is bright and homogeneous.

- No need to care about the banana shape, especially if it is to work with a single bevel. There is still some wear but, in my opinion, it is much less present and above all better distributed over the entire length of the stone. So less flattening needed overall.

- Uneven hira that is not straight works very well. It is easier to find the places precisely, such as the junction between the shinogi line and the kireha near the heel or really close to the spine. I find this technique quicker.

- Alterning scratch pattern is super simple and the stone does not want to grab the softer steel , even with strong pressure.

- Kireha can also be done this way and it's shown in this video. The feeling it's quite nice actually and in my opinion it's safe enough not to ride on the shinogi line. I start with the hira and end with the kireha and everything is crisp.

Negative
- Unfortunately the stone will deform and you have to work as much as possible over the entire length. This is especially important for coarse stones as they wear out faster.

- I have never tried on a kurouchi finish. I don't know if this technique would be well adapted but I doubt it.

- Without slurry you can't really play with contrast for a foggy kasumi. This method is made to cut but limits creativity.

- I have tried on natural ones and the result has always been disappointing. I didn't investigate further but I intend to try again soon.


So this is it! I wanna know if you ever tried this technique and if you have some clues or tips. I like to experiment and try new things and I find it interesting. The stone use in this video is a Shapton 320.

 

[mengwong]

Fascinating! This reminds me of how the Sharpmaker suggests switching between the flat face and the corner of the triangle rod, for different contact geometry and pressure.

 

[KasumiJLA]

Fascinating! This reminds me of how the Sharpmaker suggests switching between the flat face and the corner of the triangle rod, for different contact geometry and pressure.

Pressure seems like to be the key when working on a tight surface like this. I will try some natural today and post some test results.

 

[mengwong]

Unfortunately the stone will deform and you have to work as much as possible over the entire length

Would using the short side of the stone make it easier to reset by flattening?

I imagine the stone clamped in a vise standing up.

 

[KasumiJLA]

Would using the short side of the stone make it easier to reset by flattening?

I imagine the stone clamped in a vise standing up.

That's interesting!

I think with a "f clamp" it's gonna be easy to do. Like not placing the stone vertically but working on the narrow side at least. Thank you for this wonderful idea!