Magic Marker issue

We've all encountered blades with a portion of the bevel that seems to resist setting/sharpening because of a subtle frown, spine anomaly, etc. The usual advice is to use the MM to ensure all portions of the blade are meeting the hone with the stroke being employed.

I've noticed that often the MM, at least to casual inspection, indicates the entire blade does meet the hone -- yet the stubborn part remains stubborn.

When this happens, I've begun to look microscopically at that problematic part of the bevel. What I notice is that while gross inspection suggests the MM is being removed, the microscope reveals areas -- sometimes at the very edge, sometimes partially up the bevel -- where remnants of the MM remain, although gross visual inspection indicates otherwise. That part of the bevel is not meeting the hone, at least to the same degree that the other sections are.

Guess what I'm saying is, don't rely on unmagnified evaluation of the MM. It can be misleading.

Anyone else experienced this?

Yup. The bevels from both sides are not meeting, so there is a small, blunt area still there. It's not because you're not getting contact in that area, it's just because more steel needs to be removed to create the bevel.

This is one "drawback" of the MMT, but adding in the TPT or TNT will make it easy to find when this is happening. Those are specifically bevel tests, while the MMT is a contact test.