Chefs can stay sharp with proper knife care
By John Fladd
The first thing Jim Renna wants you to know about kitchen knives is that the sharper a knife is, the less likely it is that you’ll cut yourself.
“There’s more injuries on a dull knife than a sharp knife,” he said, “because you’re using more pressure on a dull knife.” And if the knife slips while you’re cutting, all that pressure you’ve been applying to an onion gets directed to your hand or fingers.
Renna has been a chef and cafe owner for 30 years. He has recently expanded his business to sharpening blades, particularly kitchen knives, at Kitchen on Demand Knife Sharpening (3 Executive Park Drive, Bedford). Last spring, Renna bought a new toy.
“I purchased this unit back in June,” he said, proudly nodding at his sharpening machine. “This is a Tormek T8. It’s water-cooled. It’s got all types of jigs for axes and scissors, pocket knives, just all different kinds of anything that needs to be sharpened. I did a lot of practicing, reading up and watching a lot of videos online, so for five months that’s all I did was practice, because I didn’t want to start advertising until I knew what I was doing and everything was going to be perfect.”
After decades of using knives professionally, Renna knew there is much more to kitchen knives than most home cooks think about.
Different styles of knives, for instance, are not interchangeable with each other. Each is designed for a particular use.
“You’ve got your paring knife,” he said, “which is a smaller one. You’ve got your boning knife with a thinner, more flexible blade. Then you’ve got your regular chef knives, which everybody uses for cutting. And you’ve got your serrated knives for bread and things like that.” He said that when choosing a chef’s knife, for instance, a cook should look for one that fits well in their hand and is heavy. ”So you want a heavy, balanced knife that you don’t have to apply a lot of pressure to,” he said. You’ll get safer, more exact cuts.
Renna said most home cooks don’t get their knives sharpened nearly often enough. “The recommended [frequency] is six to eight months,” he said. “Most people do like five years. Most people don’t even think to have them sharpened.”
Each knife has an ideal angle that it should be sharpened at.
“Most kitchen knives are sharpened at a 15-degree angle,” Renna said. “But a customer just brought a knife in that’s supposed to be sharpened at a 20-degree angle, so that’s a big difference. Shun [brand] knives are at 16-degree angle, so that’s a one-degree difference, but it does make a lot of difference.” Renna’s sharpening unit has several ways to ensure an exact angle when he sharpens a blade, but it gets even more complicated — as he sharpens blades on the grindstone wheel of his sharpener, the wheel wears away slightly. He needs to measure the wheel regularly and work its new size into his calculations.
One other thing Renner wishes more home cooks knew about is the difference between honing and sharpening.
If you have a round “chef’s steel” in a knife set — the type you see television chefs running their knives along — its job is not to sharpen a knife. It hones it. As you put a knife to work, the microscopic edge of the blade gets bent out of shape.
“Honing straightens the edge of the blade,” Renner said. “If you use [your chef’s steel] often, your old knives will stay really sharp for a long time. There’s a skill to it, and [cooks] should find out how to use it.” He gives the example of a barber running a straight razor along a leather strop. The leather isn’t grinding away at the blade; it’s pulling the edge into line.
Kitchen on Demand Knife
Sharpening
3 Executive Park Drive, Bedford
The cost to sharpen a blade is $1.50
per inch of blade, or scissors for $7 each.
Turnaround is about 24 hours, or over the
weekend for a Friday dropoff.
Visit the Kitchen on Demand page on
Facebook.
Featured photo: Photo by John Fladd.
