Why Ice is slippery (physics); and ROH

[Query]

An interesting but somewhat technical article: http://lptms.u-psud.fr/membres/trizac/Ens/L3FIP/Ice.pdf (Why Is Ice Slippery, Physics Today, 2005.)

Note that recent physical models and experiments suggest that ice is always "wet" (liquid or semi-liquid) in a thin layer at the surface, at ice rink temperatures, even without pressure from the skate, or frictional heat.

Note also that the liquid layer is only a few tens of nm high, which may help explain why ridiculously tiny changes in blade shape matter.

I recently sent an email to Edge Specialties (they make the Pro-Filer hand sharpening kit), arguing for more available ROH options in available kits, because the width of the strip that hydroplanes across the surface, could be strongly affected by edge angle - in particular that in a simple geometric model it is proportional to the difference between the edge angle and 90 degrees. (Brad, who manages Edge Specialties, has argued that differences in blade shape of less than 0.001" shouldn't matter, so minor ROH changes aren't so important.)

In particular, I argue that the blade sinks into the ice along the sides of the blade, so that the width of the strip that lies in or on top of the surface is approximately proportional to that angle, which is in turn approximately proportional to (Radius of Hollow)/(Width of blade). The pressure on the strip, available to cut into the surface and create clean edges, is inverse to that, and should be proportional to (Width of blade)/(Radius of Hollow).

I have no direct observational evidence that proves that this model is exactly correct, but I believe that many of you would agree that even small ROH changes matter. Yes?

No doubt a similar argument could be made for rocker curvature...

[Query]

Work continues in this area, suggesting that the physics of ice is extremely complex.

E.g.,

2019:

https://www.cnrs.fr/en/why-ice-so-slippery

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.9.041025

2020:

https://journals.aps.org/prx/pdf/10.1103/PhysRevX.11.011025

2021:

https://www.insidescience.org/news/why-ice-slippery-its-not-simple-question

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.11.011025

I admit there are parts of these papers that are beyond my ability to understand.

But it does look like there has been a return to the idea that ice is lubricated by a very thin film of of water, as a liquid, gas or mixed solid/liquid layer that has substantially different charateristics from ordinary solid or liquid water.

And - no surprise here - there seems to be a belief that the best skating blades and skis need to spread out the pressure over a relatively wide area (because friction increases with pressure), bounded by very sharp edges to allow for pushing and maneuvering.