Cutlery glossary

 

The following glossary is expected to grow as I use technical words in my articles. It is not by any means complete at the moment.

 


Bolster:
Part of a knife, generally made of some kind of metal, placed where the tang of the blade enters the handle. It is meant to protect the handle but also often plays a decorative part.

 

Grind:
Part of the blade that is progressively thinned out to result in a very fine cutting edge. There are various ways to grind a blade (flat grind, convex grind, Scandinavian grind etc.). Every type of grind has its pros and cons.

 

Heat treatments:
In knife making there are usually three types of heat treatments that are done in this order:

1- Normalizing which consists in:

– heating the steel to a given normalizing temperature (depends of the type of steel)
– holding this temperature for a given time
– cooling at a rate suitable for the steel.

Normalizing is intended to:
– eliminating or reducing the effects of previous operations (deformation, welding or previous heat treatment) by putting the steel in a stable, uniform, unstressed state
– giving the steel a structure allowing it to respond properly to further heat treatments.

2- Hardening which consists in:

– heating the steel at an appropriate temperature
– cooling it by quenching usually in a liquid like oil or water. Hardening brings steel to a very high hardness. However this comes with a cost: the steel usually becomes very brittle. Note that it is possible to selectively harden given parts of a blade. This leads to a very hard cutting edge, with the hardness decreasing towards the spine to give the knife a better toughness (see the Mora Bushcraft Triflex for example).

3- Tempering consists in :
– heating the steel once or multiple times at a lower temperature than the hardening one
– holding this temperature for a given time
– cooling at a rate suitable for the steel (usually very slowly).

Tempering aims to reduce the unwanted effects of hardening by softening the steel (thus making it less brittle) and making it tougher.

 

Paring knife:
The blade lenght on a paring knife ranges from 7 to 12 cm. The blade must always have a very pointy tip and a good thickness. Its main task is to clean (scrape), peel and cut all types of vegetables. It is also a very versatile knife in a kitchen.

 

Rockwell hardness scale (HRC):
A mechanical test allowing to measure the hardness of a steel. For knives, the general guidelines are the following: a Rockwell value of 56 to 60 is considered adequate for general purpose knives. 56 is on the softer side (case of the Swiss army knife), so the cutting edge will wear quite quickly but the steel is less brittle. Conversely, 60 is quite hard, so the sharpness is more durable, but the steel will tend to be more brittle. Some of my carving knives score 61-62 on the Rockwell scale. For carving wood they are unbeatable, but against bones, their cutting edge will disastrously chip.

 

To strop :
Technique aiming to get a razor sharp edge by polishing a blade. Stroping is usually done by rubbing the cutting edge on a piece of leather. It is can be used either after sharpening a blade on stones, or as a maintenance operation to keep a keen edge for a long time.

 

Tang:
It is the part of the blade that penetrates into the handle. Generally speaking, the longer and beefier it is, the better and stronger is the knife.