SP (Swedish Technical Research Institute) has on behalf of Testfakta compared nine kitchen knives. The laboratory has among many tests, tested the sharpness, resistance against rust and bending ability.
Following knives have been tested:
Fiskars Functional Form
Mac NKB 85
OBH Nordica Oden kockkniv
Chroma type 301
Sharpness and wear
The sharpness of the knives was tested according to a standard method based on ISO 8442-5. The knives were cutting back and forth in a mechanical movement through a pile of 15 mm thick paper tie. Since the weight of the knives is different, they were loaded with different weights in order to achieve the same pressuring force (260 gram). After 10 cycles, the amount of paper cuts was counted.
For measuring how fast the sharpness of the knives are worn out, the test was performed twice. In between these two tests, the knives cut 30 cycles of paper ties of high wearing quality (copy paper of high chalk).
For testing how good the knives are against rust, the laboratory used a method based on ISO 8442-2.
Before testing, the knives were washed with acetone and then mounted in an incubator on a plastic holder with a air pressure piston tilted about 45 °C ,with the tip and the edge pointing downwards.
The knives were dipped in 1% sodium chloride at 60 ±2 °C. The testing was carried out for 6 h with the dipping done every 10 seconds per minute. Then the onset of rust was studied ocularly and microscopically. The damages were graded on a 6-grade scale according to the standard ISO 4628-1. Only the rust on the blade was evaluated.
On a well-balanced knife the handle and blade weigh equally the same. The laboratory balanced the knives on the exact place of the forefinger when the knife is used. Then the pressure from the tip was measured on a balance.
The laboratory investigated the bending ability by fastening them 1.5 cm from the tip and loading the knife at the right angles with one kilo’s pressure (10N). The knives were loaded 27 cm from the tip. When the load was displaced, the remaining bend was measured on the tip of the blade in several grades sprain.
The safety of the handle
The laboratory examined the shape of knives between the handle and blade. All knives, except Ikea and Porsche have some kind of gliding blockade between the handle and blade. This prevents the hand from gliding against the edge. On Ikea and Porsche knives, the blade slopes against the handle without any blockade, meaning that the hand can glide against the edge of the knife.
The grades for the different tests have been weighed together for a final grade as followed: sharpness 40%, resistance against rust 30%, bending ability 10 %, balance 10%, and glide blockade/safety 10%.