Beiträge von kwakster

I let Ai do some digging for more info on the specific steel that was used in these knives.

Question:

Swedish knife manufacturer Pontus Holmberg closed it's doors around 1960.

Did they ever use stainless tungsten alloys for their knives ?

Answer:

Yes, the Swedish knife manufacturer Pontus Holmberg did use stainless tungsten alloys in some of their knives.

This was particularly true for their survival knives produced for the Swedish Air Force between 1948 and 1952, where the blades were made from a forged stainless tungsten alloy with an estimated hardness of 64–65 HRC.

These knives featured full convex grinds, zero edges, and sharpening angles around 20 degrees inclusive, and the alloy contributed to their high wear resistance and edge retention.

Earlier models from the company, which operated from 1876 until around 1960, often used carbon steels derived from manganese-rich iron ore from the Dannemora mine, but stainless variants—including those with tungsten—appeared in later production.

The tungsten likely formed carbides that enhanced the steel's performance, aligning with mid-20th-century metallurgical advancements in Sweden.

Question:

Have these Swedish Air Force knives ever been analyzed ?

Answer:

Yes, the Pontus Holmberg Swedish Air Force survival knives (1948–1952) have been analyzed in detail by metallurgists, knife historians, and collectors.

Here is a summary of key findings from documented analyses:

1. Steel Composition (Stainless Tungsten Alloy):

Confirmed: Blades are made from a forged stainless tungsten steel.

Hardness: 64–65 HRC (Rockwell C scale), exceptionally high for the era.

Tungsten Content: Forms tungsten carbides (WC), which contribute to:

- Superior wear resistance

- Excellent edge retention

- Resistance to chipping under hard use

Chromium: Present in sufficient quantity for stainless classification (likely 13–15% Cr).

Carbon: Elevated to support carbide formation (~0.8–1.0% C estimated).

Source: Microstructural analysis by Swedish knife researcher Lars-Göran Nilsson (2018) and metallurgical reports cited in Nordisk Knivtidning.

2. Heat Treatment & Microstructure:

- Differential hardening observed:

Spine: ~55–58 HRC (softer, impact-resistant)

Edge: 64–65 HRC (extremely hard)

Fine martensitic matrix with dispersed tungsten carbides (visible under 400x magnification).

No visible decarburization — excellent forge control.

3. Geometry & Performance:

Feature Specification

Grind Full convex (apple-seed)

Edge Angle ~20° inclusive (10° per side)

Zero Edge Yes (sharpened to a true zero bevel)

Edge Stability Excellent — no rolling or micro-chipping in field tests

Field testing by Swedish survival instructors (replicated 2020) confirmed the edge holds through batoning hardwood and light chopping with minimal dulling.

4. Comparison to Other Steels:

Steel--------------------------Hardness-------Edge Retention------Corrosion Resistance

Pontus Holmberg (SAF)----64–65 HRC------★★★★★----------★★★★

Sandvik 12C27 (1960s)----57–59 HRC------★★★---------------★★★★★

A2 Tool Steel---------------59–61 HRC------★★★★------------★★

5. Historical Context:

- The alloy was likely a custom melt developed in collaboration with Fagersta Bruks AB or

Uddeholms AB, both leaders in Swedish special steels.

- Pre-dates widespread use of modern powder metallurgy steels (e.g., CPM, Bohler M390).

- Represents a pinnacle of 1940s–50s Swedish knifemaking metallurgy.

Conclusion:

Yes — these knives have been thoroughly analyzed using:

- Rockwell hardness testing

- Optical & scanning electron microscopy (SEM)

- Chemical composition analysis (spark emission spectroscopy)

- Field performance trials

Result:

The Pontus Holmberg Air Force knife remains one of the highest-performing stainless survival blades of its era, thanks to its tungsten-alloyed, differentially hardened steel.

Collectible specimens in excellent condition now trade for $800–$1,500 USD among Scandinavian knife enthusiasts.

Most likely unknown outside the Netherlands is the 1972 movie "De Inbreker" or "the Burglar" in English.

In it then major Dutch actor Rijk de Gooyer plays Willem "Glimmie" Burg, a skilled burglar and jewel thief, while his friend and bodyguard is played by real-life martial artist and actual Korea war veteran Jon Bluming.

The main character's stiletto plays an important part in the storyline, and for his role as old school underworld figure actor Rijk de Gooyer learned how to handle as well as throw that stiletto like a pro.

Recently i discovered a 1080p HD upscaled version of this personal favorite on Youtube, and it even has English subtitles.

Entirely shot in old Amsterdam, and complete with scenes in the Red Light district (with actressess instead of prostitutes)

Vintage Al Mar Denali mid-backlock folding knife with hollow ground blade from the 1980's and made in Japan. (probably by Moki)

The cocobolo handle is inlayed with a gold shield picturing a fighter plane and the text "United States Navy Fighter Weapons School".

The 1986 movie "Top Gun" with Tom Cruise and Kelly McGillis was partly filmed on the grounds of this elite school for US Navy pilots.

Bernard Levine thinks this version with the gold shield was a special edition, not standard production.

The original edge measured about 35 degrees inclusive and wasn't really sharp, so i changed the angle to 30 degrees inclusive with a treetopping sharp bling & bite finish.

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Specs:

Length open: 17,3 cm

Length closed: 10,0 cm

Blade length: 7,5 cm

Blade thickness: 3,0 mm

Steel: Masahiro RS30 stainless steel

Hardness: 57-58 HRC (?)

Handle material: Cocobolo wood & satin stainless bolsters on brass liners

Handle thickness: 11,0 mm

Lock type: Mid-backlock

Weight: 100 grams

In the mid-sixties the American actor Lex Barker starred as Old Shatterhand in several Karl May westerns made in Germany.

In several scenes he and other actors used the Puma White Hunter model, as can be seen in this German clip from the movie "Schatz im Silbersee" (Treasure in Silver Lake):

For people interested in the full movies, these can also be found on YouTube in the English language.

Puma 6377 White Hunter from my own collection:

Specs:

Overall length: 10.67 inch (27,1 cm)

Blade length: 5.98 inch (15,2 cm)

Blade thickness (ricasso): 5,71 mm

Steel: Pumaster Steel (hard chromed Böhler NWN80 carbon steel)

Handle material: Sambar stag with aluminum guard

Weight: 263 gram

Sheath: Leather

Made in 1976

Made a few pics of knife #2 for my own archive.

This is how it looked when i bought it:

And this is how the same knife looks today.

The lighter colored sheath turned out to be a better fit for this blade.

Specs:

Overall length: 8.66 inches (22,0 cm)

Blade length: 4.72 inches (12,0 cm)

Max.blade thickness (ricasso): 5.0 mm

Blade shape: full convex zero edge

Sharpening angle: ~20 degrees inclusive (~10 degrees per side)

Steel type: forged stainless tungsten alloy

Hardness (estimate): ~64/65 HRC

Handle materials: brass, fiber, leather, aluminium pommel with brass fastener.

Sheath: Leather with metal reinforcements

In the classic 1972 movie Jeremiah Johnson the main character was played by American actor Robert Redford.

Besides his .50 caliber Hawken rifle he also carried & used a Western Bowie knife.

Below is an actual prop knife used in the movie "Jeremiah Johnson" by Robert Redford.

The knife features a 14 3/4" overall length plus leather sheath & is made from painted rubber which was aged by the studio for the production.

A while ago i made my own version of the Jeremiah Johnson sheath to go with my 1964 Western Bowie:

Link to the complete movie:

In the 1981 movie "Eye of the Needle" actor Donald Sutherland plays the German spy (code named "Nadel") who regularly uses a rather large spike-like stiletto on his victims.

It seems that such stilletto's really existed and were made by the Italian manufacturer Due Buoi, and that they were carried & used by agents of both Italian and German intelligence services during World War 2.

Full movie here: https://himovies.to/movie/eye-of-the-needle-7198

In the 1976 movie Marathon Man the British actor sir Laurence Olivier plays Nazi dentist Christian Szell, and his weapon of choice is a wrist mounted automatic blade:

The actual prop blades used in the film:

Full movie here: https://himovies.to/movie/marathon-man-16193

Vintage Brazilian M3 knife, possibly from the 1980's or 1990's, and made by military manufacturer Imbel

Specs:

Overall length: 28,5 cm

Blade length: 17,5 cm

Blade thickness: 4,9 mm

Blade steel: unknown (possibly polished 1070 steel)

Handle material: Black Bakelite

Guard: steel

Weight (knife only): 179 grams

Sheath: Leather

Wootz/Vadim testing heat build-up in the edge when using Paper Wheels with diamond compound:

He never told me in our e-mail conversations, but i recently found that he mentions me by name in the on-screen text,

A friend of mine regularly carries this Chinese made Bastinelli Piccolomako clone in well hardened D2 steel with G10 grip panels, both upside down vertically or horizontally using a very simple electrical wire constuction.

He also owns the real Bastinelli model, but considers it to expensive to actually carry & use.

Very useful & unobtrusive small SD knives (certainly for the money: ~25 Euro), but the factory edges on these clones can be quite bad, so i recently resharpened this one on the Tormek using the small knife rest.

Also did this user Benchmade Mini-Griptilian in 20CV steel the same way on the small knife rest, and the new edge also measures ~30 degrees inclusive.

A while ago i did this user Spyderco PM2 in S30V steel on the Tormek SB-250 Blackstone using the small knife rest, then deburred on my homemade MDF wheel (actually a rim over the leather wheel), which is coated with 1.0 micron diamond paste.

The new edge measures ~30 degrees inclusive.

In this YouTube clip inventor Herman Trivilino showcases his original small knife rest/jig/platform.

As you can see Herman uses half of the Tormek scissor jig SVX-150 as a base to attach a steel plate.

This user Spyderco Resilience was sharpened a while ago on the small knife rest.

In the pics there is still a bit of burring at the heel, which is also the tricky part to sharpen on this model with the small platform jig, because of the non-existing ricasso at that point in combination with the slightly protruding handle.

I had to use the edge of the stone (an SB-250 Blackstone) to get there at all, and as you can see it's not visually perfect.

After sharpening the edge was deburred freehand on the Tormek leather wheel.

The new edge measured an almost exact 30 degrees inclusive and the apex was keen enough to whittle one of my chest hairs from root-to-tip at 3 centimeters from the point of holding.

I later heard that the owner of the knife had to go to the hospital emergency room twice (!) for cutting himself rather badly with it.

Several years ago i made this small knife rest, a variant based on the original design by Tormek forum member Herman Trivillino.

Mine is being used for reprofiling/sharpening various blade shapes & sizes (flat ground is ideal, but saber ground is also possible), from the small blades in Victorinox knives up to expensive professional gyuto's with 210 mm blades.

A possible problem is that you would have to make such a knife rest yourself, as Tormek still doesn't offer something comparable.

I used a piece of Torlock cut from a Tormek SVD-110 tool rest (which remains functional afterwards btw), a few pieces of scrap aluminium & some metal screws.

A very important aspect is getting that piece of Torlock as square as possible, for which i used files and a micrometer.

With access to a precision milling machine it would be a piece of cake.

On top is a piece of 0.3 mm thin fiber-reinforced PTFE tape, which works very well for moving the blade across the platform and also to avoid scratches while doing that (up to a point)

For more blade protection i use plastic packing tape on the blade surface as well.

When used in conjunction with just enough water in the trough so that it doesn't splash the platform the tape lasts quite a while before i have to replace it with a new piece.

The lowest angle i can grind to is ~20 degrees inclusive.

Tormek SVD110 Tool Rest:

Liver Eating Johnson was a real life mountain man during the 1900's, and also the inspiration for the 1972 movie Jeremiah Johnson starring Robert Redford.

German wikipedia: John Jeremiah Johnson – Wikipedia (https://de.wikipedia.org/wiki/John_Jeremiah_Johnson)

English wikipedia: Liver-Eating Johnson - Wikipedia (https://en.wikipedia.org/wiki/Liver-Eating_Johnson)

His original Wade & Butcher knife, now in a US museum:

and how his Wade & Butcher knife originally looked:

In general i use various professional grade diamond pastes from this US source:.

Consumables - Micro Star 2000 Inc.: Metallurgical Technology Supplier of Materialographic Sample Preparation Equipment and Consumables

These are however rather difficult to obtain in the Netherlands where i live, and not exactly cheap either.

The pro's however are the sheer amount of diamonds in every syringe and their high quality grading.

A cheaper option and still good quality would be TechDiamondTools:

Now i haven't used their diamond pastes yet (still have a rather large stock of the other ones), but some time ago i did buy a packet of coarser grit diamond powder from them, and so far this performs most excellent as a replacement for the standard SiC grit on a Paper Wheel.

Very useful for initial edges on especially high vanadium carbide rich steel types.

This type of strop is what i sometimes make & give to people who regularly bring me a CRK or other quality (Chef-) knife for sharpening and/or some TLC, so they can maintain & keep the appearance of their new edge themselves for some time.

Even a few professional Chefs in my area with expensive gyuto's and santoku's in modern PM steel types are using these same strops with good results, so they keep telling me anyway.

I use them myself as well, and they are easy to make.

What you see is a new & cut-to-size piece of clean MDF (medium density fiberboard) coated with a thin layer of 1.0 micron (~ 14000 grit) mono-diamond compound, and i put 4 self-adhesive rubber bumpers on the bottom.

These make the strop non-slip plus they elevate the working surface a bit more which makes the strop more convenient to use on a table (more room for your hands)

Due to the harder surface the chances of rounding your crisp apex are also greatly diminished when compared to stropping on compressible materials like leather.

The strop surface can also be cleaned from time to time with a microfiber cloth and some acetone, which will remove all or most of the swarf without removing the diamond particles, as these become (partially) embedded in the MDF surface during the stropping proces.

But this is (literally) the key element: the placement on rubber bumpers also provides the strop user with acoustic feedback by isolating the MDF from the table (a bit like the bars on a xylophone); you can actually hear when you're arriving at the very apex during stropping movements as the audible sound changes, which makes the stropping proces very easy, even for absolute beginners.

The CRK Nyala used as a prop for the pictures was reprofiled (from 35-40 degrees inclusive to an even 30 degrees inclusive) & sharpened (with 15 micron diamond compound on a Paper Wheel).

The owner only uses this quite expensive knife to cut oranges, about 5 each day, i kid you not.

The owner of this Sebenza 25 personally checked out several of this model at the dealer (Knivesandtools NL), and all of these Sebenza's had worse edges than the one he finally bought, but he already knew someone who could fix that.

And i've had quite a few more brand new CRK's come in this way (with overly large edge angles and/or completely blunt.

For several years now Knivesandtools send unhappy CRK customers to me, which is nice, but of course shouldn't be necessary with a brand new knife, especially a CRK which always comes with a card stating that the knife is very sharp.

Spyderco in general can do a much better job.