From my (currently invisible) blog:


TPT - Thumb Pad Test
Performing The Test:
1. Hold the razor in your dominant hand and aim the edge upward.
2. Place the fingers of your off hand along the downward facing spine for absolute control over how your thumb contacts the shaving edge.
3. With a moistened thumb pad, draw your thumb very gingerly across, not along, the edge repeating all along its length to feel how it grips or bites into your thumb print.

Interpretations:
1. If the edge has a faint tickling sensation and just starts to grip onto your thumb pad then you are in the right neighbourhood for a shave test.
2. If the edge bites and grips your thumb pad relentlessly wanting to cut in and not let go, then the edge may be overhoned.
3. If the edge tickles your thumb and feels like a very sharp knife with a good cutting edge then you are not sharp enough. This sensation is usually felt coming off a medium hone like a 4,000 grit waterstone.

Finer points:
1. The cross edge action of the thumb is done much more carefully than one would normally do it for a knife since you are looking for different responding factors.
2. I regularly perform this test after every few laps on the hone to chart the progress in the creation of the edge.
3. The sensations described above are from my personal vantage point and your perceptions may vary. The definitions cannot substitute for the actual experience of sensation since perceptions depend primarily on the tactile sensitivity of the tester. Calloused hands, for example, may find it difficult to accurately grade a razor's edge with this test.

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