Using Very High to Super High Rockwell Rated Blades. Practical Considerations for Super High* Rockwell Rated Knives
I own 5 high Rockwell rated knives (my Linder Super Edge knives). See below some example images:
The rest of my knives fall into HRC 55-58,
Some examples: (some random Spanish made knives I own)
so from HRC 58-59 I will say these are high Rockwell knives.
For example:
Any knife rated above HRC 59 is very high hardness knife
just another example:
and any thing like HRC 63 and above are Super High Rockwell knives.
These are somewhat arbitrary ratings. An average metal working file has a Rockwell of approximately: HRC 60-64, sometimes HRC 65 for special files. So one can see that a knife whose HRC is 64 is capable of cutting metal!
EDGE MAINTENANCE
In terms of edge maintenance, it is generally considered very poor practice to use any knife until the edge turns blunt. Let me define "blunt" as a knife edge which will not cut any common materials even with excessive force applied by the hand alone.
However, a "dull" edge on the other hand may cut such similar objects, however not without undue resistance and or resulting on some damage to those objects. The consequences of this "damage" may or may not be of any relevance to the task at hand.
It's probably clear that sharpening any knife at home will provide the optimal circumstances in terms of time taken and equipment utilized. The reason here is that if one is sharpening at home, it means you are not generally in a hurry to use the knife/axe/machete etc.and one can work without time constraints looking over your shoulder!
In contrast, there are 2 types of field sharpening: One is when you are based around a vehicle and other is when you have no vehicle; for example you are backpacking in and limited by what equipment you can logistically carry.
Clearly when you have driven to your site (eg hunting base/campsite) you can basically bring as they say "everything but the kitchen sink", and thus equip yourself with all but motorised sharpening devices (ok, bring a generator and go crazy with belt sharpening tools LOL).
I will focus upon the second type of scenario where one is limited to what is carried upon their backs.
In terms of hiking to camping sites, I know no one personally who has independently remained away from civilisation for more than 10 days unaided by others dropping food/fuel, equipment etc. and requires a knife for such existence. Long distance trekking doesn't count as usually one will at some point encounter other trekkers and thus can be aided by others. Hiking well travelled trails also doesn't count as it's possible (and often done) to replenish stocks/swap materials etc. during such long hikes. Bike touring remote regions around the globe does count speaking from personal experience.
Essentially we are limited to where and how long we can travel, by the amount of water we can either carry or find along the way.
It could be possible to dull these edges of say a HRC 55-58 knives if these activities occurred at a high frequency or there were "accidents" from striking something very hard.
However, with careful usage I could go a week out and not have to resharpen the edge at all because in reality unless you are working on a "process line" you are simply not going to be dulling an edge of a quality outdoor knife IMHO in such a short period of time.
This brings me to the point of super high Rockwell knives.
Recently on the channel @BushCampingTools, I demonstrated the use of a knife (the Extrema ratio ONTOS II S600) both during the night and day for just over 3 weeks duration, showing some things which may be encountered requiring the use of a sharp knife. Such as but limited to: making other tools for example digging sticks to avoid using a knife as a shovel; cutting up various food stuffs; chopping (in the absence of a saw or hatchet) trees down to build structures; Extracting coconut water for drinking and or further food preparation in the absence or limited freshwater availability. I've actually done this latter activity in real life for several months subsisting upon coconut water for both cooking and drinking however, we used a machete for this purpose! During the above tests of the ONTOS II S600,
the edge was not sharpened/stropped nor was it sharpened/stropped upon arrival from the manufacturer, so as not to bias the test results. At HRC 64 this edge did not dull at all and why not? After all, at HRC 64, such a hardness, this edge could cut metals (of lower hardness) without damage.
Some have suggested this type of steel hardened to such high Rockwell values would not be suitable for long term survival usage due to the difficulty of resharpening in the field. I would argue based upon what I've already said above that this would not be the case. During a long term stay in the field one is to be more care with what they cut and how they treat their tools in general to provide a maximum longevity, especially to edged tools. In fact, I have done this with a 3 month stay in the field subsisting between acquiring food via money with fishing and foraging during those in between periods. We were very careful with how we treated our knives and in fact we had zero equipment other than stones to sharpen any knife during this entire term. So this brings me to the point of what can one do in order to keep sharp such high Rockwell knife edges whilst during prolonged journeys away from home?
Firstly, as I said, don't let the knife edge go dull. Bring a strip of leather or even better still, wear a good quality leather belt to use as a stropping surface. Carry (and it takes no room and could easily possibly last over a year with careful use, a small quantity of diamond stropping agent, say around 3000 grit (see below).
For example but not limited to:
#WorkTuffGear / #JENDE Diamond honing products.
3000 grit diamond compound will definitely hone the edge of a steel at 64HRC against a quality leather strop. In fact it will do better than hone but actually remove material as apposed to simply polishing the edge.
If a knife edge will cut with almost no effort the following objects then you can take it as very sharp:
Shave leg hairs
easily cut tomato skin
easily cut mango skin
easily cut fish skin
(forget paper as paper as a test as it is fibrous and even if the knife edge is not super sharp, one the cut begins the structure of the paper will help for it to grab against the edge of the knife and aid the cut, whereas the above objects the materials are no fibrous in nature.
Probably most people can access a tomato with todays global trade, maybe a mango is hard to find and maybe you live where you can't fish or buy fresh fish. Don't go crazy cutting paper and cardboard as most cardboards and papers have clay mineral fillers and these will only serve to unnecessarily dull your knife edge. But if that's your thing then don't let me stop you.
@Bushcampingtools seen here fishing a 70km long (uninhabited-save for a dozen houses at the entrance) beach on Eastern Australia
* In a nutshell: Don't let them go blunt!
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