CATRA testing and "initial sharpness" feel

[Skidoosh]

I'm wondering what to make of initial sharpness, how sticky sharp a steel feels. For instance super blue doesn't hold an edge very long but it still has the best initial crazy sharpness of an edge that I can find. When I compare it to S90V, Super Blue wins for "sticky sharpness" but S90V blows it away in edge retention. Is there any metallurgical/Engineering understanding of initial sharpness?

 

[Twindog]

I think any steel can be sharpened to "sticky sharp" levels, but some are easier to sharpen to that level than others. For most of us, sharpening is both a science and an art. The variability of sharpening skills is huge.

 

[Karl H]

I could be wrong, but I believe:
- higher matrix hardness or very fine participates = more sticky sharpness
- larger hard precipitates (I.e., vanadium carbide, chromium carbide, etc) = less sticky sharpness
- sharpening with an abrasive that is much harder than the hardest precipitates in the steel = more sticky sharpness

All of these factors affect how smooth or “toothy” the apex will be. I think what you are looking for is a smooth, thin apex without exposing or tear out of large carbides, rolling, or chipping.

For more info, I recommend checking out Knife Steel Nerds.