Most sharpeners assume that moving to a finer grit stone will always produce a smoother edge and a finer scratch pattern. But what happens if a 16K sharpening stone appears to leave deeper scratches than an 8K stone? While it sounds impossible, this exact question recently sparked an interesting discussion among experienced sharpeners.
The topic came up in the Edge Snobs Facebook group after member Will M. noticed what looked like deeper scratches appearing on his edge after using a 16K Shapton Glass Stone. At first glance, the finish looked rougher than the edge produced by the previous 8K Shapton Glass Stone, which raised an obvious question—could a higher grit stone actually make the edge look worse?
Repeating an Old Experiment
Rather than relying on opinions, Will decided to document what was happening.
After finishing his edge on a 20K Suehiro Gokumyo, he intentionally returned to the 16K Shapton Glass Stone to observe how the bevel changed over time. The edge was photographed after every ten sharpening strokes, continuing all the way to fifty strokes.
Interestingly, this experiment closely mirrors an earlier discussion from 2011 often referred to as the 16K Shapton Glass Controversy. At the time, some sharpeners also believed the 16K stone was producing an edge that appeared rougher than expected, particularly on straight razors.
The Sharpening Progression
The sharpening sequence followed this order:
- 8K Shapton Glass
- 16K Shapton Glass
- 20K Suehiro Gokumyo
Once the edge had been refined to the 20K finish, it was deliberately worked again on the 16K stone. The goal wasn’t to improve the edge, but to observe exactly what happened as additional strokes accumulated.
Microscope images were captured after:
- 10 strokes
- 20 strokes
- 30 strokes
- 40 strokes
- 50 strokes
This provided a clear record of how the scratch pattern evolved throughout the test.
What Happened?
The results were surprising.
The 20K Suehiro stone produced a clean, highly refined finish that removed the previous scratch pattern. However, after returning to the 16K Shapton Glass Stone, new marks gradually became visible on the bevel.
By approximately 30 strokes, small chips or irregularities began appearing along the edge. These areas became easier to identify under magnification and stood out from the otherwise polished bevel.
Continuing to 40 and 50 strokes helped smooth the edge somewhat, but the bevel no longer looked as clean as it had immediately after the 20K finish.
Does This Mean the 16K Stone Is Worse?
Not necessarily.
There are several possible explanations for what was observed.
One possibility is that the finer stone simply revealed imperfections that were already present but hidden beneath the previous scratch pattern.
Another explanation is that excessive sharpening on any fine stone can begin to affect the very apex of the edge, especially on extremely thin straight razor bevels. Rather than improving the finish, too many passes may gradually create micro-chipping or edge fatigue.
Pressure, steel type, sharpening angle, slurry, and even the condition of the stone can all influence the final appearance under magnification.
Why This Matters
This experiment highlights an important point about sharpening.
A higher grit rating doesn’t automatically guarantee a better-looking bevel if the sharpening technique isn’t controlled. The number of strokes, pressure applied, and the condition of both the stone and the edge all play significant roles in the final result.
It also reminds us that microscope images should always be interpreted carefully. What appears to be a deeper scratch may actually be steel structure, lighting differences, or microscopic changes occurring at the edge itself.
Final Thoughts
The results of this experiment don’t provide a simple yes-or-no answer. Instead, they raise interesting questions about how ultra-fine sharpening stones interact with highly polished edges.
While the 16K Shapton Glass Stone appeared to introduce visible changes after repeated sharpening, that doesn’t necessarily mean the stone performs poorly. It simply demonstrates that sharpening is influenced by many variables, and the highest grit isn’t always the only factor determining edge quality.
Experiments like this are valuable because they encourage sharpeners to question assumptions, test different techniques, and rely on careful observation rather than expectations alone.