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This is how sharp your knife is

Published Aug 31, 2010

How much does it cost to cut? What impact does the sharpness of the knife have for the butcher, precision and quality. How sharp is a knife? These are questions which researchers at KTH are looking for the answers to.

In a study called STAR - Styckarnas arbetssituation (the working situation of the butcher) - KTH researchers Jörgen Eklund and Kjerstin Vogel in cooperation with trade organisations and companies are studying what the effect of the sharpness of the knife has for the individual butcher and the results he or she can achieve.

“The hypothesis is that the sharper the knife, the less the physical effort involved for the individual. The work moves along faster and the quality of the cut is better. It also facilitates the butcher’s work,” Kjerstin Vogel explains, researcher at the School of Technology and Health at KTH.

Kjerstin believes that the results will also show that a sharp knife does not only facilitate the work of the butcher, but also increases the company's profitability.

“We hope that the study will help awaken interest so that the industry starts a course which explains how the butcher sharpens and takes care of his knife. Our model is in Canada where there is such a training course,” says Kjerstin Vogel.

How do you measure how sharp a knife is? To measure the sharpness of a knife, you need a special tool which has been purchased from New Zealand. There are no similar tools in Sweden today which makes both the tool and the study quite unique.

An experimental group which consists of butchers is used in the study. They will be testing three different knives. Two of these are of conventional steel and the third uses a new steel, a so-called semi-ceramic steel which is harder than normal steel.

The study will show which knife is the most durable and whether there is any individual differences between the butchers. The butcher is allowed to use the different knives for a period of one working day for each knife. The sharpness of the knife is measured continuously and the butcher's pulse rate is also measured throughout the entire working day. Questions regarding how the butcher feels, the amount of work he produces and quality are additional parameters which the study will take into consideration.

“Cutting is a craft and a knife is the butcher's most important tool. If a sharp knife can do the work more easily and faster for the butcher, this will have an effect on the butcher's working environment in a positive sense,” says Kjerstin Vogel.

The study is expected to be complete in two months time and before the end of the year, the results of the analysis will be presented.

For more information, contact Kjerstin Vogel at 08 - 790 48 11 or

Peter Larsson