Japanese Utility knife from Lee Valley


A shot of the blade alongside a Martha Stewart Chef's knife and Kyocera ceramic utility knife (blue handle) for comparison :

utility knife, chef's knife and
	kyocera ceramic

Specifications

The Japanese utility knife is a mere 0.057" thick and about one inch wide. It has a main sabre-flat primary grind which is 0.46" high ground at 2.9 degrees, and has very light hollow, beyond the visible, with a secondary chisel ground edge bevel. The edge is 0.005" thick near the base and runs past the visible limit near the tip. The edge angle is difficult to measure because of its size, but it is approximately 20 degrees included. The edge is uniformly sharpened along its length to a fine polish (less than 5 micron), and can push cut photocopy paper straight down and shaves very well.

This knife has exterior layers of stainless steel forge-welded to a high-carbon steel core of SK-5 at 60 +/- 2 RC. The side laminate is 410 stainless steel. The core extends up to about a quarter of an inch and is clearly visible. This combination of steel gives the edge holding and ease of sharpening of a very hard carbon steel combined with the ease of machining and corrosion resistance of the soft stainless steel on the flats. The edge will obviously corrode just as easily as a plain carbon steel.

Lee Valley recommends sharpening on a 1000 grit water stone which is far more coarse than the NIB finish. They also warn about using sharpening steels, assuming the grooved "butchers" steels.

Stock testing

The utility knife required 118 (10 g) to push cut light thread and 0.45 (4) centimeters of edge was to slice 1/4" poly under a 1000 g load, very high sharpness in both respects. On 3/8" hemp, with a straight push cut, the blade took 24 lbs to cut through the cord near the base of the blade which decreased smoothly to 17 lbs near the tip where the edge was slightly thinner. The blade had aggression on a slice as the force was reduced to 13-15 lbs on a 2" draw.

UPDATE : since the performance of the Japanese utility is so high and it is so affordable, it has been used extensively when reviewing kitchen knives (ref) as well as when examining the use of various knives in the kitchen.

Miscellaneous kitchen use

For soft vegetables and fruits, the advantage to cutting ability due to the slim profile of the japanese utility knife was not that critical. However on binding materials it gave a level of cutting ability which was significantly ahead of other production kitchen knives, even for those regound to more acute edge profiles.

In general the thicker and the denser the vegetables the greater the difference in cutting ability and the Japanese knife can handle even thick sections of turnips and such without any excessive rocking, or needing to use the off hand on the spine for additional pressure. Physical ability is also a factor. The knife was loaned to friends with disabilities which limits hand strength and control and their positive reaction to it was very extreme.

With some foods a slightly more coarse finish gave slightly better performance as a straight push cut isn't as effective as a slice. However because of the highly efficient geometry, it could often out slice blades with a more coarse finish.

Miscellaneous commentary

This knife has a very ergonomic and comfortable handle, the grip was much preferred to more squarish Henckels. The knife is also very light and thus generates little fatigue regardless of grip. Using it for many tasks generally done with a paring knife, such as peeling potatoes, the utility knife did well, being easy to handle, though the wider blade does inhibit tight turning. However a more aggressive handle finish would be preferred on occasion for some cutting as it can get a bit slippery when working with oily foods.

The lack of corrosion resistance does however force some care. The blade has to be rinsed frequently after cutting any acidic foods and should not be left wet for any length of time. After dicing up a few onions the edge took a visible patina which increased after every similar session even if the blade was very quickly rinsed and dried.

The only real downside to this knife, aside from the corrosion resistance is that the edge is likely not as tough as the common softer stainless steel production blades. Given the common kitchen misuse (edge contact with pans, plates, other blades etc.) this knife would take major chipping damage. It is also not made to cut bone, and isn't nearly as forgiving as the production stainless blades when used in this manner which will just dent.

Using the knife in a more utility role (rope, cardboard and the like), it does very well as the cutting ability and edge retention is high. It would make a functional choice for a light duty camp or outdoors knife. It isn't of course a hole digger or substitute for a tent peg, but for normal cutting work it would be quite solid. The only real drawback would be an inability for light chopping and baton work.

Sharpening

Because of the high hardness, assuming that it does not rust, the edge will stay sharper significantly longer than the production stainless blades. When honing, it is sharpened as normal on the beveled edge side, then lapped it on the flat side to cut off the burr. It was sharpened it in this manned after considerable kitchen use, honing the bevel with five micron SiC sandpaper and then lapping the flat with a 4000 grit waterstone. Because of the the light hollows in the primary grind and the laminate nature of the knife the speed of sharpening was very high and was easily brought to a hair popping finish. A smooth steel works well also and this blade doesn't need to be steeled nearly as often as the much softer western production stainless blades.

Overview

A summary at a glance of the abilities of the knife :

Performance summary
CategoryRating(g)
NIB sharpness very good
Cutting abilityexcellent
Handle ergonomicsvery good
Handle security good
Corrosion resistancedismal
Edge retentionvery good
Durabilitydismal
Ease of sharpeningexcellent

To clarify on the durability, the knife will handle what it was designed to do with no edge problems. However it can not be (ab)used in the same manner as the much softer and thicker western stainless knives, the fine edge needs more care in use to preserve its cutting ability.

Contact

Comments can be sent to : cliffstamp[REMOVE]@cutleryscience.com or by posting in the following thread on Bladeforums :

Lee Valley can be found online at www.leevalley.com. Photobucket.


Last updated : Jun 8: 2004
Origionally written : Dec 3 :2002
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