Yeah, you basically just run the edge across the exposed ceramic. The angle the edge makes with the sharpening surface is important, though. There’s no single bevel angle that works for all knives; sharper angles cut more cleanly but are less durable and can’t handle as much force, so a sushi knife needs a different bevel than a machete. Whatever angle you choose should be consistent all the way through.
Unless the knife is old or very dull, you’re probably best off trying to match the factory angle. An easy way of doing this is to run a Sharpie along the beveled part of the blade and then check it after a couple of strokes; you’re looking for the smallest angle that’ll take the ink off all the way to the edge.
I don’t think the bottom of a mug is capable of enough precision to make the Sharpie trick worthwhile (or even (=flat) enough to talk about choosing bevel angles), but here is more info about knife sharpening than most people need :-)
It’s never going to give you as consistent an angle as a water stone is, certainly. But I’d still expect a difference if you tried to bevel one knife to 30 degrees and the next to 12.
What’s the procedure for sharpening a knife with the bottom of a mug? Do you just drag the side of the knife along it a few times?
Yeah, you basically just run the edge across the exposed ceramic. The angle the edge makes with the sharpening surface is important, though. There’s no single bevel angle that works for all knives; sharper angles cut more cleanly but are less durable and can’t handle as much force, so a sushi knife needs a different bevel than a machete. Whatever angle you choose should be consistent all the way through.
Unless the knife is old or very dull, you’re probably best off trying to match the factory angle. An easy way of doing this is to run a Sharpie along the beveled part of the blade and then check it after a couple of strokes; you’re looking for the smallest angle that’ll take the ink off all the way to the edge.
I don’t think the bottom of a mug is capable of enough precision to make the Sharpie trick worthwhile (or even (=flat) enough to talk about choosing bevel angles), but here is more info about knife sharpening than most people need :-)
It’s never going to give you as consistent an angle as a water stone is, certainly. But I’d still expect a difference if you tried to bevel one knife to 30 degrees and the next to 12.
You may be right about the Sharpie trick.