Some things will just dull any edge angle?

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KennyB

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Jan 19, 2010
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I've been messing around a lot with my Izula's edge angle lately after finding it was at about 20 degrees inclusive. I felt that was too thin on paper, but it had been holding up really well so I have just been testing it on stuff lately to see what it can stand. The results are pretty darn interesting, and I'm really not sure what to make of it anymore.

It holds up to pretty much all of those other "edge killers" I would expect. Cardboard, carpet even, chopping against the grain on wood.

The only thing that has done it any damage?

Paper towels cut ontop of a dresser
And bamboo that was weathered and caked in dirt


So I'm not really sure what to think. Are these "edge killers" really not that much of a task for an edge, or is there just something really sinister about these paper towels or the top of that dresser? It does have a thick coat of paint ( it's a junker dresser, don't worry ) so I wonder if maybe the paint had some kind of pigment in it? And the bamboo, that could be explained by the dust/dirt coated on the outside of it...

Anyway, yeah, at this point I'm really not sure if it's too thin or not. I guess it's not rocket science, I'll just keep trying out different things and seeing how it holds up, but this has caught me by surprise. Oh, and my conclusion is just that whatever was on the bamboo and that dresser that dulled my edge probably would have dulled an edge at any angle, like it was dust or silica or something. Like to know what you guys think on that matter...
 
I noticed edge chips/deform at 20deg inclusive for my vg-10,zdp,d2,m4 blades when hitting hard clumps of silica/rock/epoxy. High psi forces are localize at edge against particles, so the edge either chip or roll. Push cutting a lot of cardboard will dull the edge quite fast too, although hard non-paper particles are smaller in cardboard, therefore lessen the damage. Try 0.25mm 30deg (then 40deg) incl micro bevel to see if it would improves edge retention.
 
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I was searching the web about compounds a while back, and did see that many of the abrasive compounds we use for stropping & sharpening, are also used as pigments in paint. In fact, I think if you search on 'chromium oxide' (same stuff as used for green compound), you'll see much more uses for it as a pigment. I think I've read here on the forum, some 'old timers' have been clever enough to use green-painted wood as a makeshift hone or strop, obviously knowing what the 'green' was made of. Aluminum oxide (used in ceramic sharpeners and polishing compounds like Simichrome & Flitz) is used in a similar manner, mostly for whites and maybe as a base color, for mixing other colors too.

And cutting anything with dirt/dust (silica) on it can dull an edge quickly, too. Real dirty cardboard can do it. Fiberglass is another edge killer.

I sometimes 'test' my edges by cutting paper towels, but only free-hanging, without the hard backing. The paper towels by themselves don't seem to faze the edges at all, as with most paper.
 
Obsessed with Edges said:
I was searching the web about compounds a while back, and did see that many of the abrasive compounds we use for stropping & sharpening, are also used as pigments in paint. In fact, I think if you search on 'chromium oxide' (same stuff as used for green compound), you'll see much more uses for it as a pigment. I think I've read here on the forum, some 'old timers' have been clever enough to use green-painted wood as a makeshift hone or strop, obviously knowing what the 'green' was made of. Aluminum oxide (used in ceramic sharpeners and polishing compounds like Simichrome & Flitz) is used in a similar manner, mostly for whites and maybe as a base color, for mixing other colors too.

And cutting anything with dirt/dust (silica) on it can dull an edge quickly, too. Real dirty cardboard can do it. Fiberglass is another edge killer.

I sometimes 'test' my edges by cutting paper towels, but only free-hanging, without the hard backing. The paper towels by themselves don't seem to faze the edges at all, as with most paper.
Click to expand...

Yeah, I remember finding that when searching for some CrO aswell so that's why I wondered that. It hit me to test it out on a different backing, and it certainly wasn't the paper towels. Not sure if it would really be the paint since it seems like latex based paint to me, but it was certainly something with that dresser-top.
 
Latex would be the binder in the paint, the glue that holds the pigment onto the surface. It's the pigment that would be the abrasive that dulled your knife. Chromium oxide green paint is abrasive no matter whether it's oil based or latex. Apart from the dirt on the bamboo likely being abrasive, bamboo has an extremely high amount of natural silica in it...kinda makes me wonder why I am seeing more and more cutting boards made of bamboo...
 
I have noticed masonite dulls my para quickly (cutting open packages on top of a work bench). Oh and zip-ties...........
 
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