Today’s sharpening

Today, I worked on Honbaduke for an 180mm Kama Usuba made of Gingami-3 steel.

I started with a diamond stone to shape the foundation, then moved on to a medium-grit whetstone and finally to a natural whetstone. I included the medium-grit stone in the process because I wanted to take advantage of the slurry created during sharpening to refine the edge to a razor-sharp finish.

This technique involves using the abrasive particles from the whetstone itself to polish the edge—something I like to call the ‘Free Particle Attack’ method. It’s incredibly effective for achieving a beautifully honed edge.

Diamond stones are great for maintaining a flat surface during sharpening.

However, medium-grit whetstones tend to develop a slight warp after just two full passes from tip to heel. (To be precise, even one pass can cause some warping!) For knives like Usuba, which require precise straight lines and have wide bevels, even a tiny warp can prevent the desired sharpening results.

To address this, I performed serious flattening of the whetstone after every two passes—totaling over five times throughout the process. Since the foundation was already set with the diamond stone, I used the medium-grit stone solely to achieve the ‘Free Particle Attack’ effect!

If I had relied on the medium-grit whetstone for the entire process, the number of flattenings would have been far higher.

I finished the sharpening with a Suita natural stone. At this stage, the edge is so sharp it feels like it could pierce through anything. After the handle is attached, I’ll refine the edge for completion.

While this piercing sharpness gives an incredible cutting feel, I suspect the edge won’t retain its sharpness for long.

• 2015-01-09