Large Opinel

A shot of the Opinel alongside the large drop point Twistmaster which is basically a modern take on the Opinel :

Specifications

The Opinels has a 3/32" thick carbon steel bladewith a full primary grind. The grind is full flat on one side with just a hint of a convex curvature to other. The included angle of the primary bevel is approximately 6 degrees. The edge bevel was barely existent, the blade was only 0.002-0.004" thick behind the bevel, just wide enough to see. The full specifics on the blade profile :

Stock testing

Sharpness : the Opinel at best it could rip and tear materials, little actual cutting ability. Under magnification the edge was just shaped, not honed. The edge was cleaned up on some sandpaper, and finish sharpened at 22 degrees producing a micro bevel about 0.1 mm wide.

On 3/8" hemp, with a fine finish produced by a 800 grit ceramic rod the Opinel could push cut the through the rope with 12.5 (3) lbs and slice 10.5 (5) lbs. Roughing up the edge with a 600 DMT rod increased the slicing ability to 9.5 (5) lbs . As the push cutting ability is so high a slice just turns into a straight push cut.

The wood carving ability was in general very high. on some Basswood the Opinel would cut a point off of the one inch hardwood dowel in 1.8 (3) slices.

The tip is very thin and thus penetrates materials well, but has little strength. It has no significant ability to dig / pry in wood.

Kitchen

With the thin stock and full height grind which tapers to a very thin and acute edge the Opinel worked very well as a paring knife. It was very comfortable in a traditional side grip due to the round handle lacking any square edges typical of modern folders which tend to be flat and also problematic ergonomics wise in such grips due to clips. Peeling potatos and making other similar cuts on apples and melons, the Opinel was almost effortless, pretty much in the same cutting class as an optomized paring knife, however the blade stock is a little wide and thus it doesn't turn as well. However in contrast to most utility knives it is still preferred even though it can be more awkward to turn simply as it cuts so well. For example even with the edge on the Jess Horn reground it still wasn't in the same class as the Opinel cutting wise and thus isn't as efficient aside from point work due to the much finer tip taper.

As a utility knife it in general cut very well, though comparing it against an optomized japanese utility knife it was slightly behind, though in general much closer than most folding knives, especially the modern tacticals. Specifically in cutting small carrots, the japanese utility knife took about one lbs and barely moved the scale, the Opinel took about 1.5 lbs. Slicing through medium turnips the performance was about 3 vs 4 lbs respectively. The japanese utility knife has similar stock to and edge geometry as the Opinel but is hollow ground to minimize wedging. The japanese utility knife is also more efficient in regards to most dicing and light chopping due to the dropped blade. But again comparing the Opinel to modern folders it cuts very well. It outperforms the Military for example which on most stiff vegetables takes twice as much force as the japanese utility knife. The Military does however work better as a scraper transfering food off of the cutting board due to the raised spine because of the Spyderco hump.

For such cutting in the kitchen the edge can be ground pretty much flat to the primary and thus honed at 3-5 degrees per side. This profile also works well on meats and the sweep through the tip gives smooth cutting action cutting meat away from bone where it works more efficiently than needle like tips such as on the Jess Horn. To allow the Opinel to cut around and through bones with minimial damage the edge does have to be raised signifiantly. The cutting done on 8 lbs chickens illustrated was performed with a secondary edge bevel which was about one millimeter wide and at 10 degrees per side. This prevented any visible damage and allowed cutting through the wing tips and even sloppy cuts through the joints at the legs. The round handle does have little security and the lack of a guard does mean that care needs to be taken especially when the grip is lubricated with chicken fat. However in general as the cutting ability is so high this really isn't a functional concern.

Since the Opinel is just a plain carbon steel it will patina rapidly, which is a form of corrosion which also means the edge retention is low on acidic fruits and vegetables. It is also difficult to clean around the pivot and the handle can absorb water and swell very tight making the blade difficult to open. It is also difficult to work the lock with the grip effected by fat/oils.

Field

	Light grasses and other similar vegetation, are readily sliced by the Opinel which easily cuts through thick bundles due to the thin and acute profile. Care needs to be taken while working close to the ground as the very fine edge won't react well to cuts or impacts into rocks. It is however very light and thus heavier folders like the Manix can be more effective by using heavy swings and thus powering through thicker vegetation. The very high cutting ability of the Opinel does however still keep it competitative and in general the only real issue with functionality is the length as it limits the amount of vegetation which can be cut on a pass. With a large amount of vegetation gathered the Opinel works well to trim some thick grass shoots for quick cordage to allow the bundle of vegetation to be transported for bedding material or thatching for a debris hut or leanto. Cutting the grasses prevents them from breaking and reducing the strength and length. The grasses are combined by just laying the end shots side by side with the heads pointing in opposite directions and just wrapping the side leaves around the shoots in opposite directions and then tying them off. Do this all along the grass, add in new shoots and continue as necessary. Feet of fairly even cordage can be thus made in just 1-2 minutes, far faster than braiding. If the shoots don't have leaves then the Opinel can cut small slits and lighter vegetation used as the wrap.

Carving wood is where the Opinel excels. The cutting ability is so high that it even changes the dynamics of many tasks. Where larger folders like the Paramilitary will be used in short snap cuts to cut off small branches the Opinel will just slice them off as readily. It can even readily outclass folding knives which are generally regarded as very efficient cutting tools for wood work like the SERE 2000 and is even more efficient even than thin scandinavian blades like the Mora 2000. It also readily slices shavings from wood removing waste and wet wood and getting to the dry core to get to tinder out of deadfall after rains. Generally heavier wood to burning can usually just be picked up off the ground and added to the fire once the shavings have ignited. The edge on the Opinel though is problematic as a scraper as it is so thin and acute and tends to sink into the wood. The spine can be squared for such purposes though this reduces ergonomics in many grips. For this type of work a more robust edge is demanded than for most kitchen work as if the edge is used at 3-5 degrees it will turn visibly as soon as it hits a knots or even around small limbs. For most working a ten degree bevel is robust enough for any wood cutting to prevent visible edge damage and give devent stability.

For bucking / felling thick woods the Opinel is limited due to low blade and lock strength. Generally small blades can cut wood to length by batoning out a notch by hitting the spine with a small piece of wood. With the Opinel this will compress the lock readily into the handle so it has to be done with the lock not engaged. With no lock this limits the impacts to just above the batoning point and thus only shallow cuts can be made as once the blade is flush with the wood it can't be driven in further. This batoning is still much faster than trying to carve notches and it much more productive than trying to crack thick fresh wood by hand or grinding/hacking with a rock, but is many to one times slower than even a decent 7" blade. It isn't even in the same magnitude as a quality hatchet or saw for such work which goes through such wood in just a few seconds.

Similar issues are found with splitting. On some woods the Opinel is just used to start the cut which is then pulled/worked apart such as splitting spruce roots for cordage, or breaking down alders which will also split readily by just pulling them apart. However stronger wood can't be broken apart in this way and needs a stiffer blade and more secure lock to work it apart. As fuel for a fire, all wood burns easier when split as there is more area exposed to the flame and more air circulating in the fire so it burns hotter. Being able to effectively split wood is critically important after it has rained and the outside of the deadfall may have absorbed water. Here again the weak lock on the Opinel limits impacts and the blade as well isn't strong enough to directly pry off slabs so wedges have to be carved from either cut soft woods like alders or deadfall. The initial cut is made with the Opinel and then the wedge pounded into the cut. In the picture on the right the small wedge on top was carved from a piece of rot deadfall and only a small core was left hard. Generally wide wedges are far more efficient, but in this case there was just not enough wood and due to the narrow wedge three attempts had to be made before a decent slab of wood could be split off. With a slab removed this makes a more efficient wedge and it is easier to take apart the rest of the wood. For work of this type the more robust folders which were out cut by the Opinel for the lighter work will reclaim the top spots for efficiency on the heavier wood working. Knives like the Fulcrum are as extreme in this regard as the Opinel is as a cutting tool. A more balanced approach is found in blades like the Paramilitary which in inbetween both blades in both respects. Generally most fixed blades, even light ones like the Mora 2000 and Temperance can directly split such wood without use of wedges as there is no issue with lock stability/strength. Much more robust blades like the Ratweiler can baton split even very knotty wood without concerns.

The best way to approach heavier issues with the Opinel is to use it to build additional tools like digging sticks, wedges, and bark spuds. These are readily carves with the Opinel and allow for heavy prying of thick barks, rapid digging in most ground and splitting of heavy wood.

Miscellaneous

Cutting a variety of light materials like bubble wrap, plastics, paper and fabrics, the Opinel did very well. These materials are too flimsy to exert any wedging on a knife so as long as the edge is sharp any knife will cut that class of material well. However due to the very thin nature of the Opinel it also performed very well on binding materials. On 1/4" thick cardboard it even matches an Olfa heavy duty knife. Due to the edge and softer steel though care needs to be taken as the edge will take visible damage even on light contacts with hard objects such as a staple.

Edge retention

On 3/8" hemp, the Opinel was used to make cuts through a slice on a two inch draw. The sharpness was measured periodically on light thread and 1/4" hemp and measuring the length of blade required. First the cutting was performed with a fine finish. The results :

and repeated with a 600 grit DMT finish :

With the more coarse finish the Opinel shows about twice as much edge retention on the thread and about four times as much on the poly.

Sharpening

The Opinel's steel grinds easily but tends to have problems with burrs. The most effective way found to remove them was use of 0.5 micron chromium/aluminum oxide buffing compound. This can be a problem with high alloy steels but works well on the plain carbon steel in the Opinel.

Action and lock

The lock security is very high. It is next to impossible to accidently unlock the blade in use because of the inherent nature of the design. However unlike most modern lock designs it doesn't lock automatically when opened and requires two hands to open and can be very stiff as the wood can swell when humid. The raw lock strength is also not that high as the collar is only thin steel. A couple of times the blade was opened accidently with the lock engaged, forgetting to twist the collar, which simply popped the collar right off.

Grip

The wooden handle is slick which can be addressed with some sanding and some linseed oil. However considering the intended use, this lack of high grip security isn't a large functional disadvantage. For even the heaviest cutting the grip is very ergonomic, no discomfort. In regards to durability, this of course isn't a handle that you would want to be pounding on or with.

Summary

The Opinel is a knife designed for low stress cutting and is a highly optomized design for such work. It is exceptional for most wood cutting and works very well in the kitchen and for most utility cutting in general. The general action and ease of carry is of course behind the modern clip-its. The only real upgrade would be a preference for a harder blade to allow a finer edge geometry for the harder work and give better edge retention.

Comments and references

Comments can be sent to : cliffstamp[REMOVE]@cutleryscience.com or posted in the following thread :

• Large Opinel
• quick cord from grass
• heavy wood work with an opinel

Further information is available at the Opinel website. PhotoBucket Album.