Historical Background and Review of the German Mercator Knife (aka "Cat Knife")

The German Mercator knife is as simple as a locking knife can get. It has been around for over 140 years and has become an immortal classic. And it is still a great every-day utility knife at a reasonable price.
Here's the link to a video that was filmed at the shop of Otter-Messer, Solingen. It shows the making of the Mercator knife:
• Making of The Mercator...

[@terryfletcher6465]

I've had one for 58 years, it's lost the black coating but still a great knife, true German quality.

[@StefanSchmalhaus]

Thanks for sharing your really long-term experience with this knife!

[@terryfletcher6465]

@@StefanSchmalhaus You're welcome, it's a pleasure.

[@drbadzer]

Dang that knife is more than twice my age, and I am already showing signs of wear.

[@DARisse-ji1yw]

I have my stained, well used one in my back pocket right now... I've carried it for many years. Mine's a veteran of many days at work, hiking, & camping, and is pretty much always in my pocket or car glove box. Simple & ultra reliable given a bit of sharpening & a drop of oil. A light tap with a peen hammer on the pivot rivet closes any play in the blade that might develop over the years....

[@urmelausdemeis3495]

Welch glücklicher Zufall auf dieses Video zu stoßen. Profundes Wissen klar dargeboten. Perfekt. DANKE!

[@DaRealRincewind]

Ich habe mir die Geschichte dieses Messers vor einigen tagen bereits zu Gemüte geführt. Ein wirklich interessantes Stück deutscher Messergeschichte. Danke für die Vertiefung meines Wissens über dieses Messer. Ich werde es definitiv auf meine zukünftige Liste setzen. Beste Grüße, Chris

[@sam2cents]

Fantastic explanation and history of this knife. When I was a child I remember huge fuss and the police searching the grounds of my primary school because a 'Black Cat Knife' was found lying near the football field and for weeks parents were talking about teenagers getting more dangerous and like American gangs, and anti-social activity. Punk rock music got the blame, of course. I was always wondering what exactly a Black Cat knife was, but assumed it was just slang, until I came across your superbly executed and interesting video here completely by random.

[@StefanSchmalhaus]

Thnanks for sharing this story! I'm glad my video was kind of helpful to you.

[@joshfa5526]

Thank you for sharing the history behind this iconic cool little knife.

[@StefanSchmalhaus]

You're welcome!

[@0scarisaiah]

Awesome everyday utility knife. I am a New Zealand construction worker and use it almost daily for jobs where the Tajima etc segment knives would simply snap. Easy to sharpen and you can be rough as hell with it. Always gets a few eyebrows raised and some curiosity when I pull it out too. Makes a fantastic Christmas present for any nephews as well. Recommend.

[@StefanSchmalhaus]

I love to hear stories about the daily use of a knife. Thanks for sharing!

[@PaperWasp100]

I found one in my garage once, all rusted over and I had thought it was buggered. Just playing around with it though it opened easy enough and after a quick wipe down I found it was still sharp!

[@drbadzer]

A video as timeless as the knife it was made about. Amazing job.

[@StefanSchmalhaus]

Thank you for your kind words!

[@matthias66]

Das war eine ausgezeichnete Video, mein Herr! I was very impressed with the amount of detail you put into this video when you talked about the knife's history (its original manufacturer, alternative names, English translations for German words, history of production, etc). I can't tell you how many knife reviews I see on KZbin where guys buy a knife and know next to nothing about it when they decide to do an online review. You obviously have your stuff together. Gute Arbeit!

[@totallyfrozen]

I prefer the carbon steel too. I have a personal history with this knife. It’s one of the best knives I’ve ever owned and EDC’d that knife for many years. I after around 25 years of heavy use, I finally broke the blade in half while using it with a ball peen hammer as a wood chisel. With the tip gone, it still works as a wood chisel. After snapping my first one on half (through abuse), I immediately bought another one. I hope to always own at least one of these. They really are outstanding and underrated.

[@StefanSchmalhaus]

Thanks for sharing your personal history with this knife!

[@jeckyl321]

Qualität setzt sich durch. Danke für die, wie immer, gute Recherche.

[@903lew]

Mercator is also the map projection most of us use on our maps. Maybe herr Kaufmann was alluding to the point that his tools were also sold across the world?

[@disarmyouwitha]

After your comment on the Hubertus video, I decided to check out the Mercator as well! It's such an interesting history, I couldn't help but buy one with the classic "black cat" and one with the new Otter Messer otter!

[@RockandrollNegro]

Great video! You have a very pleasant presentation style, and clear narration. Here in the US, these knives were a staple of military surplus stores. Even in the 1980s and 90s, such stores were selling new production Otto Mercators and marketing them as "genuine Nazi fighting knifes!" which was a hilarious claim. They would also sell new Opinel knives marketed as "French Resitance combat knives" or "Legionaire folding knives."

[@totallyfrozen]

Ah…the marketing. LOL! They should be ashamed, but they will say anything to sell their goods. “Nazi fighting knife” HA! As if the German army were more intelligent than that.

[@PayneHertz]

Thanks for the excellent video. I had one of these as a kid in New York in the '70s and just rediscovered them. Had no idea of the history behind them until now. We just called them "Cat Knives" as you say. They were street legal in NYC and their flatness made them easy to carry. Really great knife with a good edge. I thought they had vanished decades ago and it is really cool to see they are still around!

[@rbrittne]

Thank you Stefan for a wonderful and professional educational video! Done as only a German could do! The K55 knife is a very dear and old friend to me. I started carrying one in 1963, which I bought brand new in New York City where I lived. One day I needed to use the knife while I was trapped at the end of a subway station as a very scary man eyed and approached me. I pulled out the knife and just held it out....shaking with fear...He saw the knife and walked away. I still have that knife.

[@tumbleweed6658]

I have my Black Cat knife for well over a good year now and it’s one of my favorite pocket knifes. I bought it based on your review which IMO is the best on KZbin it’s funny a lot of people mention you so I hope you take it as a complaint to your research. Thanks from Colorado USA.

[@StefanSchmalhaus]

Thanks for your kind words!

[@outdoorschutte6311]

Hi i habe a question how much do. These knives cost in the USA ?

[@robertmiller2173]

They are great knifes; my dad passed his one down to me! It is my favorite knife, here in New Zealand!

[@mannysilva3444]

That was excellent! I've always wondered about the cryptic "K55K" meaning. I always thought it was a military knife, and here it is revealed simply a useful pocketknife. Thanks for the enlightening information!!

[@StefanSchmalhaus]

Thanks for watching!

[@docwilkey]

thanks for the history, I own one of these knives. I bought mine back in the 70s and I now keep it on my desk for opening letters and packages.

[@labrat7357]

I have several Mercator knives and knives of similar design . One thing i noticed that is helpful to date the knife to a period is the spacer in the back of the knife. the earlier knives both Mercator and the similar knives had a red spacer made of vulcanised fiber like that that was used for tp washers and gaskets. I also have one with two shims of plain steel. and it looks original. The other thing on the earlier knives is the wear that results in an almost triangular blade shape and there is also a gradual thining of the blade thickness from all the sharpening on an oil stone.. This wear could not be produced on a" fake" vintage knife. Sadly you see many knives that are obviously modern, listed on sites like eBay as WW1 or WW2 or my great grandfathers war memorabilia by conmen . The later knives had a red plastic spacer and I have seen some that have a red nylon spacer that is not so easily fractured. I have seen some knives that were repaired/modified with a filler made of aluminium and a couple with brass filler pieces . I would love to know more of the history of these wonderful knives. All the best.

[@Goblin_Tits]

Informative and well done video. I love this knife, I have used one as my EDC for about a year. After putting it through pretty hard use, the blade play is less than I would have expected in such a well priced knife. As in the video, I also keep my carbon steel K55 sharp with a Spyderco Sharpmaker. I figured out how to open it one handed, which has made it nudge out my other one handers. It is fun to have and hold a piece of history and be able to share it with others. Thanks Stefan!

[@rmoraespinto]

Excellent video, as always, Mr. Schmalhaus. I wonder when an English version of your excellent book would be available. I have purchased the Mercator because of a video of yours and, since then, I am very happy with this knife. In fact, that is the only EDC knife that I carry for food prep -- peeling an orange with it is such a pleasure... And, as you say, its price was quite reasonable. Thank you for letting me know some of the history of such a dear to me blade.

[@StefanSchmalhaus]

The English version of my book was released last year. www.amazon.com/Gentlemans-Pocket-Knife-Construction-Beautiful/dp/0764354981/ref=sr_1_1

[@MrDagon007]

The Mercator knife is a real classic that should be in every knife collection. While such an old design, it is still an excellent cutting tool. Good overview !

[@paulhenkelman1651]

Thanks for video...nice job!! I just bought a Black Cat and it's nice to know the history. Very unique knife!!

[@Embrabrummie]

Thanks for this interesting and informative review. I have just sent for one, and look forward to using it. I am sure that when I was a boy (I am a pensioner now) my Mum used to have one of these, which her Dad brought back from the 1914-1918 War, in which he fought. It is unfortunate that it has disappeared over the years, as I would like to compare one that is 100+ years old with it's 21st century counterpart.

[@HunterJines]

Excellent video. I wish every You Tube video was so well put together. Thank you for spending the time to do the video.

[@murk3352]

I honestly think these knifes are so cool. My first name is Mercator. (Mer-K-Ter) and my dad always try’s to collect things that has my name or teach me things about my name. Thank you for the video very good

[@StefanSchmalhaus]

Thanks for watching!

[@BuSirOu]

A great Solution as EDC - Tool . I love this part of German History and Story in his backround...! I mean its possible to hold this herritage when you use and collect one of this knives and explain this another people which interesting in Knives. Best Regards and take Care Stefan

[@MrJerry160]

Wunderbar! I was interested and you sold me on the history! Greetings from southern California

[@StefanSchmalhaus]

Thanks for watching!

[@husqv5147]

Best pocket/utility knife ever made!

[@chava5000]

OMG, is always a pleasure to see your reviews!!!

[@scenicdriveways6708]

I just ordered this knife today. Nice video , thanks for sharing.

[@StefanSchmalhaus]

Thank you! I hope you'll enjoy the knife.

[@raymondtucker8565]

I just got one in the mail! It's a lot more sturdy than I thought it would be. Im very satisfied with this purchase. Thank you for the great review of the history and practical usage of this knife.

[@XDM50]

Hey Stefan, Thanks for the video. Lots of great info. Cheers, Duane

[@jamjedi1972]

Danke! Excellent video! I just received mine today along with a douk douk knife and a no.8 Opinel carbone. I love the history of these knives. The looks, the feel and the history! Thank you for telling us about this knife! Going to watch how they are made now. Take care and be safe! Hope this corona 19 crap goes away soon. I’m in the medical field and we have been on our toes. It’s just starting to hit here in Oklahoma, USA.

[@StefanSchmalhaus]

I'm safe and healthy. Thank you!

[@bigbubba5037]

Awesome review as always Stefan! You always know how to make everything flow together. Keep up the great work my friend.

[@redastrachan8978]

Stellar video! Your English is admirable. I own this knife, and it proudly stands with my pricey folders...

[@StefanSchmalhaus]

Thank you!

[@redastrachan8978]

@@StefanSchmalhaus Bitte schön (?)

[@StefanSchmalhaus]

Wow, what a story! Thanks for sharing your personal memories and experiences - even if it was a scary one.

[@1OkiePackRat]

Stefan, Thanks for another GREAT review!! I REALLY like the way that you add some history and background to your videos. Normally this wouldn't be the style of knife that I would buy, but now that I know the history behind it I just ordered one!

[@Eurotrash4367]

Very well done. I enjoy learning about classic knife history.

[@yobbos1]

I love this knife and carry mine often. Some peoplke are amazed when they see me with it, knowing that I own Benchmades, Spydercos and Emersons but the Kat knife has taken a lot of abuse over the years and never let me down. You are right it does take a terrifying edge with a little work. Thank you for the excellent vid, you are one of the best knife reviewers on KZbin.

[@samurai165]

Your videos are truly a pleasure to watch. This knife has a very interesting history, thank you so much for another great review.

[@docwilkey]

I have one myself and I like it very much. Great history! Thanks for sharing.

[@billbargo721]

Great video! Thank you for making it. I had one of these knives as a child and loved it.

[@libertyss35]

I have had this knife for about 10 years and have only been able to wonder about it's history. Thank you so much for making this video. I have had such a great affection for this knife and it is my favorite,I carry it daily. Your video explaining it's history has only made me love it that much more. The professionalism that you put into your review is much appreciated! Thank you...all the way from the great State of Texas!

[@Hagbayon]

I found one at a UK surplus shop here in the Philippines... I was vlogging when I found it. I will post it soon :) More power sir!

[@rkstew]

Thank you for your very interesting historical research.

[@jimmyggh1]

Excellent! Outstanding historical information on a great messer! Danke!

[@troy5690]

Your videos are always awesome.......another fine excample.

[@TheLazySpoiledKitty]

Stefan that was a very interesting video :). You always go the extra mile during your reviews and actually tell us about the whole history of the knife :)!!! And back than no1 needed a locking fancy tactical knife like we have today, this was a true pocket knife with a nice style may i add :). Great review!!

[@MrSharp]

Truly an amazing review!

[@michiganedge4770]

excellent video sir! thanks for the history. Very well done and informative

[@danieljacobs114]

Excellent description! Thank you!

[@chiefslief1886]

As always very interesting history and knife knowledge!!! Greetings and love from the Netherlands!

[@Templarium]

Your video was so interesting and elightening that just for that I'm going to get that knife. Thanks for sharing all this.

[@James-ke5sx]

Aha, so now I know the history of my new knife. VOSS Cutlery Co., German design. Same blade except mine has a bone handle. I use a 6'' steel from Solingen Germany to sharpen. Great knife design. It replaces my Buck 110 and Ontario RAT1 because it has features from both of those knives that I like. The Buck has lock back but it's too heavy and I do not like a pocket clip on the other knife so this German knife design is just perfect for my EDC. Thank you for the great history lesson and take care from Canada.

[@StefanSchmalhaus]

Thanks for watching! I'm glad my video was helpful to you.

[@James-ke5sx]

I have the stainless steel version coming in the mail because I liked the carbon so much

[@EDCDepot]

Great video. Loved the information on a classic knife. Mine still makes into my EDC rotation.

[@Schmidt54]

Another great, entertaining and informational video! Thank you very much! Gotta have one of these...

[@sgtflashback5442]

I recently got one and the factory sharpness is impressive.

[@LightBliss]

I have an exact copy made in Pakiistan which is just as old as the ones in world war one. I have only sharpened it once, and it is still razor sharp. The lanyard ring on mine is ornate and very artistically done. They were very ahead of their time, and no modern knives today are so undetectable while riding in your pocket, as it is very flat, just like this earth.. Steel makes a wonderful liner, such as is just now being replaced by titanium.

[@Lazylizardgear]

That was facinating and very well done. Thank you.

[@Blastmaster1972]

Interesting video! Love the history stories!

[@blowingzen]

great review, beautiful knife

[@photopuppet]

Really enjoyed this, well researched. Thanks and look forward to whatever video is coming next. :)

[@FoxtrotCorpin]

Great video. This is next on my list!

[@mccullenj]

Very informative. Great video.

[@DobermansRock]

I have carried one for over 20 years. Even in kombat in Iraq 03-04.

[@pascalstolz2901]

Sehr gut erklährt, Herr Schmalhaus!

[@ryanbrayshaw1458]

Great historical review on a great knife, well done

[@StefanSchmalhaus]

Thank you for your kind words!

[@matttheknife8293]

Great review and history lesson. Thank you.

[@StefanSchmalhaus]

Otter Messer recently revived the Mercator Multi (blade, awl, can opener, corkscrew).

[@johnstonpettigrewii127]

Really good work!!

[@grantloan]

Very cool and thanks for the history, have a great day.

[@StefanSchmalhaus]

Thanks for catching up with my old knife videos. ;-)

[@martinoamello3017]

I never realized it, but over the years I've had several versions of this knife, one in particular I carried for quite some time while hitch hiking around the western United States. I was always quite amused by police who would often take out a ruler to measure my knife then let me go when they found it to be quite legal. I'm surprised they never tested one for traces of blood even though the only blood they would have found would have been my own.

[@terrillschneider3778]

I’m going to have to buy one of those

[@StefanSchmalhaus]

Thank you for your very kind words!

[@BushcraftWoodsDevil]

Wow, thanks so much! I have always wondered about this knifes strange markings...!

[@luigib2307]

It's amazing how that folded handle is so very much like the traditional higonokami. This knife is now on my "buy" list; I'll probably get it next. I'm a little squeamish about the carbon steel but I think it's time I got over that. Thanks again for another great, historical video!

[@luigib2307]

Yes, the traditional Higonokami and the K55K are remarkably similar in that regard. Thanks for watching and thanks for your comment.

[@extrastuff9463]

Luigi Bartolomeo I'm not that surprised really, just look into our history with how technology and weapons developed over time. Many cultured discovered technologies such as spears, axes, hammers, bows, spearthrower lever aid things, etc entirely independantly of each other until worldwide spread of things between continents started to happen. Same principles apply to knives as well, human hands are pretty similar and if you find a design that works then it works. It's not unlikely for blade and handle shapes to develop independantly from each other if they were meant for similar purposes. There's only so much you can do when your constraints are: 1. As small and thin as possible 2. Good general purpose blade shape 3. Good ergonomic handle 4. As much knife inside the handle while meeting 1-3 requirements ***** As John above me said, locale matters a lot. Depending on how much salt water and humidity is in your climate (and how far you're willing to go with maintaining it) in my experience it can be an issue but not one that isn't manageable with a tiny bit of foresight and some effort. The two worst things when it comes to corrosion in my experience is when it ruins the edge and you have to grind some of it off, no big deal but it's a bit annoying to have to sharpen for that if you neglected the knife a bit. But perhaps arguably worse is if some moisture stays on it and you get pit corrosion near the edge. If that for whatever reason ends up being neglected for a long time it can penetrate well beyond the surface and make that region of the edge noticeably weaker without a way to fix it in extreme cases (you'd have to grind more edge part steel away leaving the knife in a useless state). However by either having spares or a tiny bit of maintenance and consideration in use especially when dealing with salty water and high humidity you'll be fine.

[@DobermansRock]

That's normal and means little for work.

[@todome1]

No offense, but in my experience I would call it normal. It's inherent of this very historic old-style flat folder as it has been constructed traditionally in the same style since 1867 with brads and not screws. I've collected and used this folder since 1980 and still do. Sometimes you acquire one made in 1940 absolutely tight. Other times you may receive a brand new one with a little play, so I wouldn't be "very" disappointed with your knife. They all have very sharp and easily maintained working blades.

[@luigib2307]

Thanks for taking the time to leave such an informative comment.

[@StefanSchmalhaus]

@edwyrd Thank you very much for your kind words!

[@sergeantbigmac]

Fantastic video. I mean your reviews are simply unmatched. Theyre at a whole other level man. The only thing that would make them better is if you made more! ;) Anyway, considering the average soldier (especially back then) spent more time living/surviving outdoors than anything else. I can see how in WWI this pocket knife, a sawback bayonet and an entrenching tool sharpened to double as a hatchet made the average German soldier very self efficient in the wilderness.

[@jenspiekielny4770]

Dieses Taschenmesser ist ein treuer Begleiter für einen Mann ❤

[@noahpattar78]

Hi Stefan, beautiful presentation. After watching your video I got keen interest in this knife. As I result, I ordered it from Heinnie Haynes today. 😎

[@StefanSchmalhaus]

Thank you! I'm sure you will enjoy this knife.

[@Richard-1776]

Cool looking knife.

[@Drownedinblood]

Do more of these videos they are very interesting,informative,different and all around awesome.Think you'll ever do a vid about the different slipjoint patterns,Shilin cutter,Higonokami or well other obscure-ish historical knives from around the world?

[@StefanSchmalhaus]

@wcropp1 I agree, carbon steel is more authentic on this kind of knives. Thanks for watching!

[@StefanSchmalhaus]

@jimkressin Thank you very much for your kind words!

[@samms.712]

After owning several Douk-Douks, I wanted another classic to carry. I prefer locking knives, and being in the states its ok to carry. Ordered off BladeHQ for $27, no beating that. Love the look of it, hope it performs just as well.

[@RussRockwell]

Its ok to carry anywhere in the world. "There is no authority but yourself" Ⓐ

[@samms.712]

@@RussRockwell I completely agree with you

[@Traderjoe]

This is the finest video on this great knife I have ever seen! I am uploading my own video tonight myself, after seeing you're "Trendy" version video.

[@ThePanTian]

Sehr schön, sehr interessant! I´m amazed how the americans love all these german knives and stuff

[@bobitobob3453]

This is a long time later but, we Americans love good quality .

[@fredperry9235]

@@bobitobob3453 2020 baby

[@DARisse-ji1yw]

It's a brilliantly simple & robust design !

[@jomamma1750]

Excellent video, thank you!

[@StefanSchmalhaus]

@mrmonkeyman50 Thank you! - As far as I know, today XC 75 is used for the carbon steel blades, and 1.4034 for the stainless steel blades. But I have no idea which steels Heinrich Kaufmann & Söhne used back in the late 19th and early 20th century.

[@urmelausdemeis3495]

Danke für die Information

[@evilsquirrel56231]

Excellent introduction and a valuable history lesson. I think I'll order one purely for collectors' value :)

[@justinxiong5351]

Very well done video!

[@StefanSchmalhaus]

Thank you!

[@StefanSchmalhaus]

@sweetdaddyroses I script my videos, this helps me to avoid the "ums" and "uhs". I usually don't like videos where people turn on the camera and start talking without knowing where they want to end up.

[@StefanSchmalhaus]

@TheLazySpoiledKitty Thank you, Caspar! - Doing historical research on a knife is sometimes more interesting than the knife itself. ;-)

[@maguraboy]

I have it and it is a very good work man's knife.

[@GunCollector007]

Extremely interesting!!!