W.T. Beck :
[hard and wear resistant steels]
Can I infer from your first post that knives made with such steels could be sharpened on a rock should the edge geometry be correct?
First off there would be no need to. Those knives will actually last many days of constant use for vastly more work than necessary unless you are just looking for stuff to cut up (which I am very familiar with). Unless you are spending weeks at a time, sharpening will never come up. It would only be a concern if you were in a plane crash or similar and of course kept your knife but lost your honing supplies and were looking at month+ time in a very knife demanding enviroment.
But yes, even the harder high alloy knives can be sharpened on a rock. The natural benchstones are just rocks after all. They have just been milled and lapped to a nice presentable shape. The biggest problem with using rocks that you find is that the surface is very uneven, and the consistency very low. So you get large scratches occasionally and it is therefore hard to get above a certain level. You may find it easier to use lapping pastes made from river silt depending on your location.
I have sharpened very high alloy stainless steel blades (VG-10) on everything from rocks to rusty picks. The blades were predulled by digging holes in rocky soil. It was not difficult to get them to the point where they could cut fabrics with a few passes. However you will have a hard time getting any blade back to near optimal levels on random rocks, because quite frankly, a benchstone so horrible that you would never use it, will be 10x better than what you would find under foot, otherwise those natural stones would be rather cheap, or your could make a few hundred dollars quite quickly just by picking up all those rocks and selling them on ebay.
I think of a survival knife as one that should be usable should one become lost in a forest somewhere, without access to sharpening equipment.
Quite frankly, the amount of wood you would need to cut in order to make an INFI (or similar) knife go that blunt that you could improve its sharpness on a rock would be equivalent to a small forest. What I would be concerned about for preparing for that type of situation would be maximizing your technique to minimize the strain on the knife and yourself, as well as practicing general methods to do the same.
For example, if you have to dig or root in soil, carve a stick and fire harden it rather than wear all that metal off the knife edge. Use the back of the knife to break bones rather than the edge, and practice knowing how to seperate joints by cutting the connective tissues and breaking the joints so you can minimize bone contact. Even small steps like removing the bark from a tree before chopping it can help a lot as the bark will collect dirt and debris which can be very abraisive.
As well, split up the work into sessions. This will not only let you recover which will make you more productive, but it allows the edge to relax back into alignment which will keep it sharper for longer. In general try to avoid cutting dirty materials, a simple rinsing can save you time in the long run by preventing excessive honing. Plus dirty materials are not usually great to use anyway, really dirty rope for example abrades itself which you would want to avoid since it is going to be in short supply.
Also, keep in mind all the edge maintaince techniques, which while they can't replace honing, can drastically increase the time the edge stays sharp. Experiment with stropping and burnishing which both can be done on a very wide variety of materials from human skin, woods, plastics, all manner of clothes, various bits of hardened metal and even glass. Any very critially, rinse the blade and dry if at all possible after constact with salt water or acidic juices. Even the stainless blades won't take this for very long without excessive edge damage resulting.
So in very short, yes it can be done, but no it can't be done well regardless of the steel, and no its not a real concern outside of very long extended stays and quite frankly, it isn't going to be the major concern in that case. If you have survived to the extent that the knife is dull, you been there for quite some time and have done a lot of cutting which should have included such things as; having built a shelter, gathered a supply of fire wood, stocked signal fires, collected and smoked/dried foods etc. . Now you can relax and carefully work the edge back up to par with some light honing.
-Cliff
), but I will suggest AUS-6, or the slightly "better" AUS-8 as those steels are easy to sharpen, they hold a sharp edge pretty well, and they are pretty rust resistant...All are traits that a "survival knife" must have.
But, since that scenario is highly unlikely, I'd opt for a geatly wear resistant knife. Better to count on the knife working well, than hoping for that perfect natural stone to show up for you.