Saturday, June 18, 2011

Knife Knowledge

The other day I sharpened an antique knife for a friend. It was a small butcher knife that read "High Carbon" on the face. It was stained and old looking but the handle was in great shape. Once I put it to the 4000 grit stone the edge came back to life and the thing was like a razor when I finished. I brushed a tiny bit of mineral oil on it and gave it back to my friend.

Recently I had a student ask if they could bring in their own knives rather than the school issued brand. I said it would be fine as long as they were suitable for butchery. The next day he came in with two very expensive Japanese knives that were made of "layered" steel. The edge was amazingly sharp and the knife worked very well.

The discovery of high carbon steel was truly an amazing breakthrough for knives and the ability to harden them made for much longer lasting edges. Knife blades are a combination of metals that all combine for specific purposes. There are a variety of metals used, but the primary one used today for most commercial knives is steel. Steel is composed of a variety of ingredients which can change the structure of the edge. Here is a list of knife blade ingredients used to create steel:

CARBON - a mineral that is added to iron to change it into steel. Carbon helps harden steel. The higher the carbon content, the harder the steel and the finer you can get the edge.

MANGANESE – also adds toughness and ability to harden.

CHROMIUM – Steel will rust and corrode and chromium boosts adds resistance to corrosion and staining.

VANADIUM - creates a fine grain in steel when heat treated.

MOLYBDENUM - used to increase toughness in steel and allows for more flexibilty

TUNGSTEN – a very hard metal that creates a fine yet dense steel structure.

Steel “recipes” are patented and owned by specific knife companies. Many Japanese, German, American and Swiss companies for instance own their steel patents and create knives that are unique to them. A layered knife is basically a very hard brittle steel at the core surrounded by softer steel to support it and give it some flexibility and stain resistance. A quality knife will have a combination of metals that will provide a quality edge that will last but also resistance to destructive acids, salts etc. found in many foods. Company trade secrets and techniques for creating these edges mean that the prices can be very high. A super quality Japanese blade can cost over $1,000 for a chef knife. But there are many knives well under that price that do a great job. Personally I use a bunch of different brands of reasonable knives that are typically used in the meat industry. Brands such as Victorinox, Sanelli, Giesser, Frost, Dexter all put out decent knives for low prices( $20 - $40). They all hold an edge pretty well but are by no means the same as the layered knives previously mentioned.

Along with the type of knife metal, the edge and body may have texture added to enhance the knives performance. Many knife companies now sell knives that are scalloped or “hollow” meaning there are a series of scalloped sections along the body extending to the edge. This provides for less friction when cutting and can also result in a sharper edge. This is a different technology than a “never dulling” serrated edge, such as that found on some bread knives. Serrated knives will damage meat so its best to leave them off the butcher block.

Beyond the steel edge another factor to consider is the knife handle. First compare handle materials. Some knives come with a smooth grip ebony handles. These will work fine if your hands are dry and fat free but often can get slippery. Some of the very expensive knives I’ve worked with had a riveted ebony handle I found too thin and uncomfortable for butchery, like the wrong shoes! Smooth handle knives are good for vegetable cutting and repetitive chopping but not the best for tight gripped butchering.
There are knives with plastic handles that vary in thickness and density. I often look for a textured handle like those found on a mountain bike grip, large and easy to hold with a great grip even if a little wet. Others will have a molded hard plastic that may feel a little unnatural if your hand is the wrong size.
Another option is the wooden handle. These can develop some texture over time and have a natural worn-in feel. I grew up cutting with wooden handled knives and they feel natural to me. But wooden handles can be damaged by prolonged moisture exposure so they need to be kept dry and an application of mineral oil is a good idea from time to time.
I’ve also worked with a very expensive Global knife from Japan. This single molded steel handled knife was basically one piece of hardened steel forming the handle and the blade. The handle is textured with little divots and was built into the knife. It had a good feel and the edge was incredible but it was cold and got a little slippery when wet. I couldn’t get a really good grip on it unless I kept my hand dry. Many chefs swear by these knives so again, it’s a matter of choice. Here are the basic choices for knife handles:

Hard textured plastic : durable, lightweight, many styles
Soft textured plastic: great grip, wear slightly faster, very comfortable
Riveted hard ebony: durable, many brands are thin, slippery when wet
Textured metal : very durable, cold, slippery when wet, will not burn!
Wood: damaged by moisture, “breaks in” to your hand, warm

To decide if a knife fits your hand, grip it like you are shaking someone’s hand and if your fingers fit snug and extend all the way around to the soft part of the palm the knife fits. A knife handle that is too small will feel slightly loose and will have the fingers overlapping when wrapped around the handle. A knife that is too small can lead to slippage and also fatigue. A knife that is too big can also be dangerous and can lead to loss of grip and fatigue. You’ll know when a knife is too big if your fingers don’t wrap around it securely. It will feel bulky and awkward. This can result in a dangerous loss of grip. When purchasing a knife be sure to sample a few to make sure the fit is good. Some knives have a sloping handle that enables the cutter to “choke up” on the knife and actually hold the blade with the thumb and forefinger giving the cutter more control. This technique is used for fancy smaller cuts like those done on poultry.

Whether you buy a knife for $10 or $1,000 be sure to understand what that knife will do for you. Its like skis or bikes ( can't help but think about those) If you buy a $8,000 downhill mountain bike to ride the railtrail you are simply wasting money.