A shot of the Jess Horn in ZDP-189 :
The Jess Horn is made from 3/32" ZDP-189 stainless steel. It weighs 50 grams. The overall length is 18.3 centimeters with a 7.2 centimeter blade. It has a primary hollow grind with a very thin and narrow tip. The edge is very acute and thin through the middle of the blade and is 0.014 (2)" thick and 12.7 (5) degrees per side however through the tip and choil the edge thickens and gets more obtuse approaching 0.020" thick and 20 degrees per side.
With the origional edge profile and new in box sharpness, the M16 cut 3/8 inch hemp with 9.5 (5) and 14.5 (5) lbs on a slice through two inches of blade and a push cut respectively..
The Jess Horn tips tapers through 1.05" at an angle of 2.6 degrees. On a 50 lbs push it sinks to a depth of 278 (5) pages into a standard phonebook.
 | Due to the very high initial sharpness, the Jess Horn has no problems in the kitchen even on hard to cut foods like tomatos. There is no need to use the point to start the cut or excessive back and forth sawing or significant compression of the skin, the knife draws across the tomatos and readily makes a fine slice. In general the Jess Horn works well as a paring knife being very light in hand and very slim, in comparison it makes the Delica feel like a Manix. While small folders in general are hardly fatiguing to use, the Horn is practically weightless in hand and comfortable in side grips. The clip could use some contouring, but since the force applied in use is so low it isn't really a functional issue. The blade is also narrow and thus it turns very well and easily cuts peels off curved fruits and vegetables where wider blades and especially those with thicker grinds like the Endura have problems and have to resort to taking off sections at a time while the Jess Horn can smoothly make a continuous peel. The very narrow point also works well in coring and is much more effective than a Delica or Calypso Jr. and even the Opinel or Rucksack. |
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| In general, on thick and binding vegetables the cutting ability is solid and matches the performance of the ZDP-189 Delica. This is a little suprising considering the natures of the primary grinds as the hollow grind on the Jess Horn would be expected to give it higher performance than the same hight flat grind on the Delica. However the edge angle on the Jess Horn is higher in the choil and through the tip than the edge angle on the Delica and this is critical to shallow cutting. As the Jess Horn lacks a dropped blade profile it can't be used with similar techniques as a regular chef's or utility knife in the kitchen but can still handle various utility slicing tasks with a different techique. Specifically the blade is held at an angle to the board and drawn through most foods. This works very well on soft foods like sweet peppers. However this does not work very well on very rigid vegetables like turnips which the Horn also lacks the length to cut, and the top swedge also makes off hand pressure on the tip problematic which can be used to rock blades through heavier cuts. However it will readily cut carrots without cracking and on onions the japanese utility knife needs about one lbs to slice through a medium size onion and the Jess Horn takes three to four lbs, so a difference will be noted, but the force applied is still very light. |
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| The very tapered point also goes into meats readily and efficiently trims a pork roast for rendering. The initial sharpness was also high enough to make all necessary cuts, even on the very loose sections of fat and tissues. The Horn does not have the length to work well in very large cuts of meat so often multiple passes are required but it cuts very well so in general is still prefered over larger knives especially heavy tacticals like the WB. The precise point also works well to make the pinpoint cuts around bones to allow the joints to be broken and thus prevent having to cut through the bone itself to separate the meat. It easily slips inbetween the joints and cuts away the connective tissue and reduces a 8 lbs chicken to form ready for stock in just a few minutes. The edge also had no problems making press cuts through the joints if done sloppy which required cutting through the bone caps, though this is not necessary with proper technique. In general a large knife would be prefered for most of this work, the H1 works very well as does the Temperance. A more upswept point helps out for a lot of the cutting and tends to make removing most of the cuts of meat, like the tenders, off of the bone easier as the more inline point of the Horn tends to want to cut into the bone too readily and more belly to the blade would be optimal. The Horn is though still however far more capable than the tactical folders like the X-Ray Vision. Cutting the fillets off of a section of cod was also smooth and easy with the grip being secure throughout the process and the fine point starting the cuts readily. There are some however issues with contamination around the "Jess Horn" raised lettering on the grip but a quick scrub with a stiff brush removes all debris. |
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In general there were also no issues noted with corrosion even when working on acidic fruits and vegetables for extended periods of time. It does have the common problems of all folders in that blood and debris around the pivot is problematic to clean. It would not be easy to take apart the Jess Horn for cleaning.
| On light vegetation and grasses, the Jess Horn cuts well and is easy to handle but of course lacks efficiency due to the short blade length. Grasses can be eaten, used for thatching the roof of a shelter or used as bedding or secondary insulation for clothing. They can also be braided to make solid cordage and the heavy shoots can be split with the knife and then braided to make them more flexible, similar to splitting and laminating heavy woods. The main problem with using small knives for cutting such vegetation is lack of reach which means a lot of stooping and bending and having to get very close to the vegetation which can be difficult if has thorns or other skin irritants. The Jess Horn can be lashed to a stick to make it a small bill hook which gives it much more reach. Here a light piece of alder was cut with the Jess Horn to serve as the handle. The knife easily slices through the wood near the base which was about 1/2" thick by just bending the wood to put it under tension. The Horn alsoreadily slices off the branches and trimms a little wood from the tip to flatten it and thus make it more suitable as a lashing point. A piece of spruce root was split and used to lash the knife to the alder. As the alders is a very flexible wood, it was used with a lot of wrist action, snapping the blade into the grasses at very high speed which is necessary for good cutting action. Since the grasses are very flexible a lot of speed is necessary to cut them well because otherwise they just move out of the way of the blade. With very wide swings and the ease of cutting the grass just walking along it is much easier to clear a patch of land either directly or to just gather the grasses for use. Moving on to thicker vegetation, it works well cutting down softer plants with stalks up to about half an inch thick and again using a lot of speed to do the cutting. It was raining during the work, note the spots on some of the pictures, which makes appreciation of the increase in cutting speed more direct. |
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| For splitting lumber, more robust knives can simple cut into the wood and then twist pry it apart. This doesn't take a lot of stock thicknesson one inch thick and under boards. However due to the very thick stock and distal taper this isn't an option with the Jess Horn. However the Delica easily splits clapbard and one inch board readily by twist splitting. With the Horn one efficient way to break apart the wood is to slice a taper or edge of one of the pieces to make a long wedge which can be driven into a cut made by the Horn into another piece of lumber. If the wood is easy to split then the Horn just needs to make a cut, however on thicker or more dense woods then a notch has to be cut and then the horn pressed into the apex to allow easier splitting. The wooden "knife" is hammered into the notch to readily split the lumber. Once a crack is started then the wooden knife can be twisted to widen the crack or just pull the lumber apart. It works works better if the edge can be cut from a piece of hardwood like seasoned birch but will still work on softer wood like pine. However on softer woods the edge of the splitter will need to be recut frequntly as it gets damaged during the splitting. The same general technique can be used to split some fresh woods, but generally it isn't effective unless the wood is very easy to split. |
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| Splitting most fresh woods requires wedges. Ideally small sections of deadfall hardwoods are carved to shape which are at least as dense or more dense than the wood which is being split. However even small sections of soft woods like alders can be shaped into wedges and used to split bad wood like twisted and knotty spruce. With soft wedges and problematic wood then the initial splits have to be made very close to the edge of the round and just remove thin slabs. To make the initial cut the Horn can be rocked into the wood or hammered on with another piece of wood with the lock disengaged to prevent loading the lock. With the cut made the knife is rocked vertically out of the cut with no twisting to avoid stress on the pivot. On really bad wood the initial cut may have to be made into notch to prevent the wedge from being destroyed. With knives with thicker points like the Paramilitary, the point can be driven into the wood to start the cut but this isn't a sensible technique on a knife with as tapered a point as the Jess Horn. With the first thin wedges removed they can be carved into wedged themselves. These more durable wedges allow much larger pieces of wood to be split off in the same basic manner. Unless the wedges are of very strong woods it will be necessary to keep reshaping them with the Jess Horn after every few splits because the edges will take damage during the splitting. The nature of the wedges also needs to be adjusted for the wood. In general the harder the split the wood the more gradual the taper. With the wood broken up into large sections the sections can be split themselves into progressively smaller sections by continuing to use the wedges. Once the wood is split fine enough the Horn can continue the splitting by itself by just slicing the wood or rocking it through the wood depending on the type of the wood. |
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Birch and other slim barks are readily trimmed with the precise point of the Jess Horn. For tinder such light barks are readily pulled off by hand as they peel away from the trees naturally which shed them in small pieces. However the Horn is useful for scraping the bark so it can be more easily lit from a spark and to quickly remove larger sections with minimal tearing which is useful for construction as it is very waterproof. The precise point on the Horn is also more functional on thin barks here compared to profiles like the Paramilitary or especially Endura. Pretty much any knife can make the starting cuts but a really thin tip is efficient working under thin barks and starting them away from the wood, a more upswept profile would be better however as it is more of a skinning task. On thicker pitch barks the Jess Horn's point cuts around the heavy pitch sections and then slices off the bark by working the blade inbetween the bark and the wood. However the very slim point does not take much to be overloaded so it can't readily pry off the bark which is often much faster and easiler and thus and a more robust tip if often more capable with something like the H1 being close to ideal, though a longer blade like the Ratweiler can work two handed as a draw knife which is optimal. As is true in general most large tasks are best done with small knives by using the knives to construct other tools, a bark spud shown on the left is easily carved with the Jess Horn. Using a bark spud to pry off the bark also keeps the blade free of very thick sap which is problematic to clean, especially around the pivot of folding knives. | 
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| For making a fire the Jess Horn does well gathering tinder with the precise point and efficient cutting geometry. As noted in the above it can be used to gather and break down thicker woods if necessary but often dry woods can often be located as dead fall. This is usually the best choice as wet woods don't tend to burn well, especially with small knives like the Horn which have little inherent chopping and splitting ability. Often the litter on the ground is suitable for first stage fuel unless it has rained lately in which case it is useful as smudge material. The Jess Horn does fall behind a larger knife for breaking apart heavy wood and in general most of it is faster to be cracked apart by hand than cutting with the Horn. To be really effective here a decent size knife is required, ideally something like the Ratweiler or at least a Manix or Military. These knives are all powerful enough to chop well enough to raise speed and efficiency over break apart most woods. Still though the Horn is very useful especially after a lot of rain when most deadfall is very wet and all the damp outerwood has to be cut away to reach the dry inner core. A lot of this can be broken apart by hand or even scraped with a rock, but the Horn makes it much easier. In general for most of that type of work a more robust tip would be of benefit and the Delica is more suitable and ideally something like the H1 is most functional as it combines a high cutting ability with a general high blade strength. The Fulcrum is also very useful in general for such uses due to the high blade/handle strength so it allows heavy prying and repidly removal of the wet wood. However it requires significant edge reprofiling as the initial cutting ability is far too low to allow decent wood working ability. |
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 | For harder work the Horn can handle most tasks though has to use different methods than most robust knives. A knife like the Delica for example will cut sods heavily with the point. It doesn't have the extreme taper of the Jess Horn and the point is also more robust due to the sabre grind and thicker blade stock and thus the point is easily able to take the incidental impacts off of rocks and as well pry up the occasional small stone. With the tip being the focus of the contacts this preserves the edge and thus there is only minimal blunting aside from the tip. However the ultra fine point on the Horn won't react well to even light probes into rocks as it will dull and round readily and since this is integral to its functinality the sod is instead sliced through the main length of the blade to preserve the needle like tip. Using the entire blade forces the contacts onto a longer surface and thus reduces the pressure and thus minimizes damage. The Jess Horn easily cuts off a small section of sod in just a couple of minutes with no visible edge damage and basically only blunts the knife to the extend where the edge does not catch on the thumb nail. The cutting on the right was done with the main edge angle reduced to ten degrees per side and a light microbevel at 15 degrees which was just 0.1 to 0.2 millimeters wide. It was resharpened back to fine precision work in less than a minute on a small DMT fine/x-fine pad. The very fine point also works well as a probe checking for extent of wood rot and due to the high taper is much more sensitive than very robust points like on the Endura or at an extreme, the Fulcrum. Of course the heavier points are more readily able to dig out the rotted wood whereas it has to be basically cut or sliced out with the Jess Horn which takes much more time. This additional strength of the more robust knives adds more functionality in general as a lot of work benefits from additional strength such as opening a paint can. However the Spyderco hump actually does this well and the Jess Horn has no problems opening up some cans of paint with the blade never being opened. The design is obviously not geared towards heavy cutting of metals but light material like pop cans are no problem and are easily sliced and can be made into lures readily as shown by the picture on the left. The fine tapered point comes in hand and readily drills holes, this is much more awkard with very robust knives like the Ratweiler. |
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| Bone is also a common material which can be utilized for many tools. Carving a needle is readily accomplished with the Jess Horn by first splitting the bone by tapping on the spine with a small piece of wood or rock, driving the edge through the bone. In the pictures on the right a chicken leg was used. The split bone is then carved to shape and a hole drilled in one end to make the eye of the needle. A button or fastner is made in much the same way just a different shape and multiple holes. A larger knife with a more robust edge can be more efficient at chopping into large bones but generally they can be broken with rocks anyway. Some tv cable is also readily broken down into components, the outer shell stripped and the inner copper core readily cut. Unless it is cut on a very hard surface it tends to just bend under the end and needs to be bent back by hand to complete the cut. The plastic core wrap makes a decent float for fishing, the wire get be used for needles with some grinding on rocks, and makes excellent cordage as does the outer plastic wrap. All of this cutting was done with the same edge profiled used for the sod cutting and only minor damage, less than 0.1 millimeters deep was induced from the wire cutting. |
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 | The Jess Horn works well in general cutting most light materials. It easily cuts open small containers, gliding through and opening a box of soup. It readily slits open letters and general mail with the fine point being a significant asset for such work. The Horn also readily opens a bag of salt to clean up a grave site which was over run with weeds. In general for this type of work sharpness is the main factor because the materials are not rigid enough to induce any significant binding on the blades and thus an Endura does it just as well as the Horn, and even a really robust pattern like the TAC-11 doesn't have any problems with such work aside from some awkwardness in handling. The Jess Horn is however much lighter and generally easier to carry and less of a problem with public perception so unless much heavier work is demanded it tends to be preferred over larger and more robust patterns like the Manix. |
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| The fine point of the Horn also does well as noted in the above in cutting plastics. It readily trims the end and top off a small bottle to make a scoop and just as easily cuts the bottom off of a larger pop bottle to make a functional funnel. It does have difficulty in cutting through the heavy plastic at the bottom of the bottles as the as the upper swedge is a makes applying pressure with the off hand difficult. The point can also be used to drill holes in the plastic which can then be cut through by batoning on the spine, tapping the edge through the plastic. A time consuming process, but it does allow cutting even relatively thick plastics with little stress on the knife. |
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ZDP-189 has a low grindability so removing lots of stock does take some time but this really isn't an issue considering the type of use the knife generally recieves. It is also readily reground with an x-coarse hone and diamonds or waterstones were much more effective than the typical aluminum oxide oil stones for reprofiling.
Use of DMT diamond pads tended to form fine deformation burrs. Short partial passes were made, moving about 0.5 centimeters per section of blade and alternating sides to remove the burr. Just 2-4 of such passes per side was enough to remove the burr cleanly and leave an edge from the 600 DMT stones which shaved smoothly and push cut fine newsprint.
It also responded well to a smooth steel after use, though that does induce an edge deformation bias irregardless of the steel and generally isn't recommended. The smooth steel was just used to confirm that the high hardness and carbide fraction of ZDP-189 didn't prevent such use. It also responded well to 0.5 micron chromium/aluminum oxide buffing compound to refine the edge above a 1200 drit DMT stone.
After extended use the edge on the Jess Horn was reground flat to the primary which resulted in an angle of 9.0 (5) degrees per side. Typical use was carried out with a 0.1-0.2 millimeter wide micro-bevel at 15 degrees per side. This had no durability issues even with the hard work such as the sod cutting noted in the above.
The lock back of the Jess Horn was stable under spine impacts, torques and white knuckling. The lock had no play when new and none was seen after several weeks of significant use as noted in the above.
| The Jess Horn carries tip up and is only set up for singular clip position however there are lots of individuals who do high quality after market modifications to clip positioning so this in general isn't a severe limitation. The clip is also the traditional straight profile instead of the curved and more rounded clips on the current fourth generation Delica and Endura. The straighter clips do have some ergonomic issues when cutting with a lot of force is performed as the contact the inside of the palm more readily, however the personally look more elegant and an arguement could thus be made that the Jess Horn clip is more suitable to its lines and role as a light gentleman knife which is intended more for light utility use that heavy cutting. The clip is attached by a milled out section for the head which does make it more secure than the as milled versions and much less likely to develop play/sway which can be an issue with screws set in zytel. As noted perviously, the Jess Horn is very light, it is often carried as a neck knife by clipping to the neck of a shirt or in the front pocket. This is a bit awkward to draw and clip but has its uses when the pant pockets are otherwise occupied. The laynard hole also makes a nice attachment point for a decorative braid which both helps to locate the knife at times plus can be a point of conversation with those unfortunate few who are hesitant to use/own personal carry knives. |
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The only standout issue with the grip was the clip as noted is the older straighter style which has some comfort issues. The new wire clips such as seen on the D'Allara are much more ergonomic though the flat ones made be more aesthetically matching the design of the Jess Horn as a gentlemans folder as previously noted. Overall the grip was versatile and the main complaints in its regard are typically of use far outside its intended scope of work. For example it isn't well suited to working with heavy work gloves as it is too small and thus has issues both with use and especially opening/closing. The Military is much more suited to such work, and of course such is the nature of its general design.
The Jess Horn is a lightweight knife made from ZDP-189 with a comfortable grip and very secure lock. It opens easily and smoothly with the trademaked Spyderhole and carries well with the pocket clip. It has an extremely fine point due to a entended taper and swedge and an efficient cutting edge. It works very well as a paring knife in the kitchen and in general as a precision cutting tool. It is a coherent and consistent example of functional design.
Comments can be emailed to cliffstamp[REMOVE]@cutleryscience.com or posted to :
More information can be obtained at the Spyderco website. the Jess Horn is also featured in the 2006 sprint catalogue. Nemo's commentary on the Jess Horn is entertaining and informative as always. PhotoBucket.
| Last updated : | 07 : 20 : 2006 |
| Originally written: | 07 : 20 : 2006 |
