5 Common Mistakes with Thinning Wide Bevels & Kasumi Finish (And How to Avoid Them)

As I sharpen my blades in my workshop, there’s something mesmerizing about achieving a perfectly thinned wide bevel and a stunning kasumi finish. A well-executed kasumi finish not only enhances the aesthetics of my knives but also significantly improves their cutting performance. However, my journey in mastering this craft wasn’t without its fair share of blunders. Today, I want to share the five most common mistakes I’ve encountered while thinning wide bevels and creating kasumi finishes and, more importantly, how you can avoid them.

Mistake #1: Ignoring the Blade’s Steel Composition

One of the first lessons I learned was the importance of understanding the steel composition of the blade I was working on. Different steels respond differently to sharpening techniques and processes. For instance, high-carbon steels tend to sharpen beautifully with a kasumi finish, while stainless steels can be more challenging and may require a different approach.

Before starting, I always research the specific steel type—be it VG-10, Aogami, or AUS-10. This knowledge informs my choice of grit progression and honing techniques.

Mistake #2: Rushing the Thinning Process

In my early batches, I was often tempted to speed through the thinning process. Thinning a wide bevel requires patience and precision. Rushing can lead to uneven bevels or, worse, a truncated edge that affects cutting performance.

What I’ve found works best is to take my time, spending about 20-30 minutes per side during the initial thinning. I use a coarse stone (like a 220-grit) to establish a consistent bevel and gradually progress to finer grits, ensuring that each stone's work is fully realized before moving on.

Mistake #3: Inconsistent Angle Maintenance

Maintaining a consistent angle is essential when thinning wide bevels. I learned this the hard way after noticing a knife I had worked on had a wavy edge, which not only looked unprofessional but also affected its cutting ability.

To combat this, I use a guide or jigs when sharpening, especially on wider bevels. I typically set my angle between 12-15 degrees per side for kitchen knives. Utilizing a digital angle finder has enhanced my precision and consistency tremendously.

Mistake #4: Skipping the Kasumi Finish

Once I had a nicely thinned bevel, I would sometimes rush to finish the blade without applying the kasumi finish. This was a mistake. A kasumi finish not only provides a unique aesthetic but also helps in reducing drag during cutting, allowing for a smoother experience.

To achieve this finish, I use a combination of fine-grit waterstones and a leather strop. I work through a progression of grits, ending at around 6000-8000 grit for a refined kasumi effect. The key is to ensure that I angle my strokes slightly to create that beautiful textured appearance.

Mistake #5: Neglecting Regular Maintenance

After going through the effort of creating a beautiful wide bevel and kasumi finish, it’s tempting to think I’m done. However, neglecting regular maintenance can quickly lead to dull edges and damage. I learned this the hard way when I had to redo a beloved knife that had fallen into disrepair.

Now, I take the time to maintain my knives regularly. I strop them after every use and periodically touch up the edge with a fine-grit stone. This routine not only keeps my knives sharp but also ensures the kasumi finish remains intact.

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