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Jan 27, 2007 08:59 AM

Knives: Temper, Temper!

Warning: Just about all of my knife "knowledge" is opinion and experience. Feel free to disagree or correct as required.

A critical quality in a blade is temper. A fine blade is what I call a 'live blade,' it has what I call a 'watch-spring temper.' So in considering any knife I perform the infamous Marsano Tap Test:
Hold the knife lightly between thumb and index finger, just above the rivet nearest the bolster (or thereabouts) blade flat to the cutting board, and bounce the tip on the board. It should bounce right back, eagerly, gthe way a drum stick does during a drum roll (which works mainly by bouncing the stick off the drumskin). That will be, all else being equal, a fine knife.

If the blade clanks or clunks or resists bouncing, just lies there, you haven't got a knife. You've got a paint-stirrer.

The watch-spring blade will also give a cleaner, clearer skating sound on a steel than the low-quality blade will.

A 12-inch steel from a restaurant supply is a must, I think; the 10-inchers from consumer stores are lame. If like me you've got some old carbon-steel jobs (I have a swell old Deerfield and a fartoo-big Sabatier) modern steels may be too harsh. Not sure. Anyway, I lonmg ago got an old steel from the '40s at a flean market, and always use that.

As it happens I get to a lot of restaurants (and boy am I getting sick of them), but I'll try to remember in future to seek access to the kitchens and see about collecting more edgy opinion therein.

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  1. You can go nuts testing the tempering - here's what Terry Primos says:

    "Occasionally I will take a blade to the point of destruction to see how tough it is. I do this by clamping 1/3 of the blade in a vise with the tip pointing straight down. I then slip a 3 to 4 foot cheater pipe over the handle. Next I carefully bend the blade. If the blade was differentially heat treated with a hard egde and a spring tempered spine, it should bend to 90 degrees without breaking. Otherwise the blade should not fail until it has been bent approximately 45 degrees. The cheater pipe is not just to get me a little farther from the blade, it is also for more leverage. Unless the blade was forged pretty thin, I can't bend it 90 degrees or break it by hand."

    The whole article - including a good picture of this process is at the site:

    Folks should understand that Primos is talking about testing his own hand-made knives. Tempering is not an issue with high-quality commercial kitchen knives, whether forged or stamped.