Sharp is Good

The most import­ant fea­ture of the knife is that it be sharp; razor sharp is a good start. In a recent post on the Crispin Col­loquy, D.W. From­mer II, a pro­fes­sion­al west­ern boot­maker whose skill and philo­sophy I admire a great deal, said the abil­ity to sharpen a knife is one of the most import­ant skills a boot­maker can have. His reas­on was that without a sharp knife you can’t cut an accur­ate pat­tern, or make a clean skive and that your seams won’t go togeth­er as well because they lack clean edges. The abil­ity also extends to awls and oth­er edged or poin­ted tools the maker uses. Without being really well sharpened the tool may per­form, but it won’t per­form well and that will show in the final product.

A blunt knife will drag on the leath­er you’re try­ing to cut, which will dis­tort your pat­tern and leave a messy edge. Don’t be fooled into think­ing that sharp knives are more dan­ger­ous than blunt ones. Blunt knives are much, much more dan­ger­ous than sharp ones because you have to apply far more force than you do to a sharp one, and they won’t bite into mater­i­al the same way, mak­ing it more likely that you will slip and cut your­self or at best slip and slice into the piece you’re cut­ting. The knife should be sharp enough that you don’t have to apply much pres­sure at all to get it to cut.

There is noth­ing to be gained from cut­ting things out in one pass. Take your time and make a num­ber of con­trolled, accur­ate, shal­low cuts rather than try­ing to cut through the entire thick­ness at once. This is par­tic­u­larly import­ant for sole leath­er and pat­tern­ing card­board. A prop­erly sharp knife will often cut through uppers leath­er in a single pass without requir­ing excess­ive force, but if it doesn’t don’t worry. Just go back and do anoth­er pass.

There is a lot of inform­a­tion out there on how to sharpen a knife, so I won’t go into it in great detail here. Have a look at these sites:

In wood­work­ing circles there’s a scheme called “Scary Sharp” that involves using fine sand­pa­per glued to glass. It’s way cheap­er than fork­ing out for high qual­ity sharpen­ing stones and I think this could also be applied to knives quite eas­ily.

I use a spy­derco sharpen­ing sys­tem that uses ceram­ic rods held at an angle in a plastic base:

It works pretty well, the fine stones put a good enough edge on a blade to go straight from them to a strop and pro­duce some­thing that is well sharp enough. The brass gaurds are there for a reas­on, if you for­get them you’re liable to miss the ceram­ic rods and end up with neat scars like this:

Jok­ing aside, I was damn lucky not to sever ten­dons when I did that. It took 5 stitches to close and took my hand out of com­mis­sion for a good couple of weeks. I did it because I was in a hurry. Take it easy and you’ll be a lot less likely to hurt your­self.

When a knife you’re work­ing with starts to get a bit dull it doesn’t usu­ally need to be fully resharpened. A touch-up on a strop will bring it back to sharp pretty fast. A strop is just a piece of leath­er (use smooth stuff not some­thing with an embossed grain pat­tern) glued to a bit of wood with some cut­ting com­pound rubbed into it. They pol­ish the edge of a blade so that it’s smooth and the smooth­er an edge is the clean­er and easi­er it’ll cut. I strop craft knives before I use them oth­er­wise I find they aren’t quite sharp enough. Strops are also crit­ic­al for keep­ing a good point on an awl. The one I use for my awls looks like this:

The grooves in it are from drag­ging the awl points across it. One thing about using a strop, you drag back­wards trail­ing the edge, unlike sharpen­ing where you push the edge for­wards across the abras­ive. You can get the cut­ting com­pound from a hard­ware store, just get the low speed stuff and get the smal­lest stick you can — you only need a tiny amount. The oth­er, prob­ably bet­ter, thing you can use is jew­ellers rouge if you have a jew­ellers sup­ply in your town. [edit] Lee Val­ley Tools sells a com­pound spe­cific­ally for using on strops aimed at wood­work­ers. The needs of leather­work­ing blades and wood­work­ing blades are pretty sim­il­ar so this will be a safe bet. They also have a wide array of sharpen­ing equip­ment.

Knives I Use

I use a few dif­fer­ent knives depend­ing on what I’m doing, none of them are peri­od — some­thing I will even­tu­ally fix — and at least one of them really needs to be thrown out to force me to learn to use some­thing bet­ter.

The knife I reach for more often than I should is a small snap-off blade craft knife
like this:

These have the advant­age of being cheap and sharp enough out of the box that they only need a little strop­ping to get really use­fully sharp. They do, how­ever, have one major dis­ad­vant­age for doing any pre­cise work — the blade flops around in the handle like a fresh fish in the bot­tom of a boat. This makes it impossible to cut square edges, even if you have really steady hands. This causes prob­lems when it comes to cut­ting edges for but­ted seams, and when cut­ting thick leath­er. If you cut on an angle it’ll be big­ger on on side than on the oth­er and the edges won’t meet tidily.

A bet­ter option for some­thing reas­on­ably sharp out of the box are the little craft knives with a screw clamp mech­an­ism to hold small blades in the end of a handle. I think Amer­ic­ans call them Xacto knives.
I don’t have one of those though, instead I have a couple of Swedish scalpels I got at an army sur­plus store. They get scary sharp but are a little bit chunky at the spine of the blade. Craft knives have very thin blades which can be use­ful.

The oth­er knife I use a lot is a so-called “shoe knife”. I got my first one of these for a fiver at a hard­ware store and was giv­en a box of a dozen by a friend who got them on trademe. They get plenty sharp but need fre­quent touch-ups dur­ing use to stay that way. I would advise people start­ing out to get one of these and learn how to sharpen it.

It’s not stain­less so there’s some kind of stain­ing on the blade from cut­ting damp veg tan. I’m prob­ably going to cut the blade of this one back to about half it’s length to make it a bit easi­er to con­trol.

A kind of knive you’ll see men­tioned a lot is the round or head knife. This is a dir­ect des­cend­ent of the trenket used by medi­ev­al shoe­makers, which had a dif­fer­ent handle con­fig­ur­a­tion than the mod­ern ones but was the same basic idea. I have a cheap crappy one. It sucks. If you’re going to fork out for one of these get a half decent one like an osborne or some­thing.

I have nev­er really got­ten my head around how to use this thing prop­erly. The major reas­on being that I’ve nev­er man­aged to get it sharp enough. I don’t have a mech­an­ic­al wheel sharpen­ing sys­tem and I think you need one to get a good edge on one of these. There are instruc­tions on how to cut with one of these in one of Al Stohlman’s books but I haven’t seen them.

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