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Re: Bloody thumbs

Mon Jan 27, 2014 2:25 pm

What grit are red blood cells? 8-)

Re: Bloody thumbs

Mon Jan 27, 2014 2:46 pm

SteveG wrote:What grit are red blood cells? 8-)

So given that red blood cells are 1000th of a mm

there are about 4-6 million cells for 1 microliter of blood given that there's probably a teaspoon of blood on the stone. Provided it has an even coverage.

so given an average stone size of 3x8 we have 24 square inches.

a teaspoon of blood over the whole stone 15ml = 15000 microlitres

15,000 x 4 million = 60,000,000,000/24 = 2,500,000,000 per square inch

and that's just cells, which would break down quickly under the stone. So to answer your question steve 2,500,000,000 grit

This is all going with the assumption grit for stones is calculated the same way as sandpaper.

Yes, yes. I'm a smart ass. :twisted: :twisted:

Re: Bloody thumbs

Mon Jan 27, 2014 2:54 pm

I want to see Sadden start using that on his EP setup. He likes very high levels of refinement on some of his knives 8-). Just bustin' your stones Sadden :-).

Re: Bloody thumbs

Mon Jan 27, 2014 2:56 pm

The best part about blood is the cell break down, you'd actually start to get iron particles dissolved in a liquid solution However at that point you might as well sharpen with a bowl of mineral water xD

Re: Bloody thumbs

Tue Jan 28, 2014 1:38 am

So a typical human erythrocyte is ~ 6-8 mm in diameter or about 1500 to 2k grit :) So just to go off on this topic a bit, normal RBCs (red blood cells) are shaped a bit like round rafts. not spheres so we are selectively measuring them along the raft's maximal dimension, not its thickness. Now we also have lymphocytes and other wbcs (white blood cells) in the mix too with even more heterogeneous shape profiles, and of course as this blood slurry is used the cell walls break down into smaller structures. And of course these little RBC 'rafts' flex allowing them to get through even smaller capillaries than their smallest diameters would allow if they are rigid. This unusual property (Frauhaus Lindquist effect) along with the non Newtonian properties of blood such as limited rather than infinite shear values make for a most interesting area of fluid dynamics - rheology. In a way you might think of this heterogeneous and complex fluid as more closely resembling a natural stone slurry than a synthetic slurry.

Just thought I'd share this bizarre analogy with you :)


Re: Bloody thumbs

Tue Jan 28, 2014 10:31 am

Now Ken, be careful. If you end up teaching us all how to sharpen our edges using bodily fluids and tissues, you will dry up your business :D
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