Large Opinel

Knives : Opinel Twistmaster This review consists of : introduction specifications stock evaluations general : food, utility, field edge retention sharpening overview comments and references

Specifications

The Opinel has

• 3/32" thick CV90 (AISI 1084 steel)
• 10 cm blade
• very light convex grind, approximately 3.5 degrees per side
• hint of a secondary bevel, 0.002-0.004"
• wood handle
• twist lock

Full blade profile details :

Stock testing

Initial sharpness : There was essentially no initial sharpness, at best it could rip and tear materials. Under magnification the edge was just shaped, not honed. Before further work 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. Lowering the grit finish to 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

The Opinel worked very well as a paring knife as it has the optimal profile for low stress cutting :

• thin stock
• full height grind
• very thin and acute edge

Peeling potatos and making other similar cuts on apples and melons, the Opinel was effortless, pretty much in the same cutting class as an optomized paring knife. The only drawback where a differense is seen compared to an actual paring knife is when the blade has to be sharply turned as actual paring knives are more narrow.

However in contrast to most utility knives it is in another class due to the very thin cross section. 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 and there are few folders which would be in the same class however a truely optimized utility kitchen knife will still be of a higher standard still. In particular the japanese utility knife could still out cut it as it has a similar primary profile and edge geometry however it made out of significantly thinner stock.

Specifically :

• small carrots
  • japanese utility : 1 lbs
  • opinel : 1.5 lbs
• medium turnips
  • japanese utility : 3 lbs
  • opinel : 4 lbs

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. For example it easily outperforms the Military one of the highest cutting ability performers of modern tactical folders but which takes almost 50% more force than the Opinel to cut similar vegetables.

For light cutting in the kitchen on :

• fruits
• vegetables
• meats

For meat work in general 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. There is however a concern about handle security as the grip has no texture and there is no guard so working around fish and meats has a significant risk because any oil or fat which gets on the hand or grip will severely compromise security.

However if the Opinel is going to be used for meet work around and for light cuts through bones the edge has to be thickened. The boning work on the right was done after the Opinel has secondary bevel of approximately :

• 0.01" thick
• 10 degrees per side

In general for these types of knives what tends to happen is as they are sharpened and the edge thickens they eventually start to be used for harder and harder work and unless they are regound to thin them back out to the as-boxed profile they eventually tend to be used for such work and the new ones get used for the low stress work were more cutting ability is desired.

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. As the cutting ability is so high but the blade is so light the optimal method isn't to use it like a small machete but instead just grab a thick bundle and then just slice through it.

There is a concern though working close to the ground because the natural very thin profile and almost non-existant secondary edge means it will not react well to contacts off of rocks, though if there is damage it is very easy to repair as the grindability of the steel is very high (essentially maximum).

Comparing it to larger and heavier folders like the Manix the Opinel can not compete with the direct cutting ability as those folders can be used as small machetes and just chop through the vegetation. The Opinel can be lashed to a small pole to make a small billhook for this purpose but again concern would have to be taken to ensure the edge doesn't accidently hit something hard which would easily cause damage up into the primary grind.

In general where the Opinel comes into being more useful than larger folders outside is for precision work. For example with a large amount of vegetation gathered the Opinel easily trim grass shoots for quick cordage to allow the bundle of vegetation to be transported for bedding material or thatching for a debris hut.

Cutting the grasses prevents them from breaking and reducing the strength and length and makes combining them into cord much more efficient. The grasses are made into cordage 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.

While the Opinel can not keep up with the larger folders as a small machete it is much lighter in hand and for this type of work which there is a lot of in outdoor crafting (bark work for example) it is simply more efficient.

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 and since it has no significant alloy carbide then even natural stones work very well. The only real issue is that compared to the same steel in harder knives with a higher martensite percentage then there can be some issues with burrs if the edge is over sharpened. The optimal way to deal with this is to not form a burr as noted in the video to the right. However if it does happen and the edge is over sharpened and a prominent burr is formed then :

• clean and flatten the stone
• use very light force
• increase the angle significantly (as in double it)

Then use 1-3 light passes per side to set a micro-bevel and then back sharpen at the original angle.

Action and lock

The lock security is high, in fact 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
• requires two hands to open

The main issue that most would have is that lack of one handed opening and beyond that it can actually be difficult via the nail nick. A simple modificaton to increase ease of opening is to just make a cutout in the handle to expose the nail nick.

Grip

The handle is a very simple and generic design, circular at the front and tapering to cylindercal and swells/flares for security at the end. The wooden does comes a little slick which can be addressed with some sanding and some linseed oil.

As the handle is fairly thick (almost an inch) it isn't nearly as flat as most modern pocket clip pocket knives which are less than half as thick in general. This extra thickness does maket pocket carry a bit of an issue but it drastically improves comfort in extended use as it is so filling in the hand.e

In regards to durability, this of course isn't a handle that you would want to be pounding on or with as it has all the common issues of a wood grip and requires regular care which isn't overly complicated just an annual inspection and if necessary coating with some linseed oil and use of epoxy if there are any micro-cracks.

Summary and Overview

In short :

• high lock security, low lock strength
• not one handed opening, no clip
• thick handle, comfortable but carry issues
• exceptional cutting ability due to thin cross section
• steel sharpens easily to a low grit finish or high polish

In short this knife cuts very well and is very comfortable in hand in a wide variety of grips. However it does not have the lock strength, ease of carry (clip) and one handed opening of modern folders.

Comments and references

Comments can be sent to : Large Opinel

More pictures can be seen in the PhotoBucket Album.