Thread: Darwin straight razor

Originally Posted by BobH

Make that two, I am working on a 7 day set.

Bob

Still burns me, I had a nice one...had a small bend at the point, probably could've flattened it with a two books, someone thought they were doing me a favour (not Val from Gentleman's Den) by making it into a shorty.....

Had the original coffin box and all...

I am not a specialist at all, but in my research I found this book - Woldman's Engineering Alloys. It lists different allows by manufacturer and here are Darwin and Milner Inc. (Darwin's US division) patents:



The closest is "Patent Cobalt Chrome Steel":



Darwins of Fitzwilliam Works, Sheffield took over Darwin and Milner company in 1926, which apparently held these patents.

Originally Posted by Rigensis

I am not a specialist at all, but in my research I found this book - Woldman's Engineering Alloys. It lists different allows by manufacturer and here are Darwin and Milner Inc. (Darwin's US division) patents:

The closest is "Patent Cobalt Chrome Steel":



Darwins of Fitzwilliam Works, Sheffield took over Darwin and Milner company in 1926, which apparently held these patents.

I'm far from being an expert either but I did find a current definition of stainless steel here What Is Stainless Steel? .

By the looks of it the Patent Cobalt-Chrome Steel has a chromium (Cr) content of 11.75 - 13.75, which I take to be a percentage, and meets the minimum 10.5% chromium content level in the definition of stainless steel.

To positively know if the razor is stainless you would have to know if they used the Patent Cobalt-Chrome Steel in making the razor. OTH you could have the blade tested but I guess that would involve destructive testing and not really wanted.

Chances are looking pretty good that it is a stainless steel razor but that is just based on assumption.

Bob

Originally Posted by BobH

I'm far from being an expert either but I did find a current definition of stainless steel here What Is Stainless Steel? .

By the looks of it the Patent Cobalt-Chrome Steel has a chromium (Cr) content of 11.75 - 13.75, which I take to be a percentage, and meets the minimum 10.5% chromium content level in the definition of stainless steel.

To positively know if the razor is stainless you would have to know if they used the Patent Cobalt-Chrome Steel in making the razor. OTH you could have the blade tested but I guess that would involve destructive testing and not really wanted.

Chances are looking pretty good that it is a stainless steel razor but that is just based on assumption.

Bob

I found a book online called "Handbook of Stainless Steel" where in section "How it all started" it says:

At the same time [1911-1912] in Sheffield, England, Brearley was experimenting with 12–14 % Cr steels and observed that they did not etch in normal etching acids. He also noticed that Cr steels resisted corrosion much better in the hardened than in the annealed condition. Brearley saw commercial possibilities of this material in cutlery and gave non-rusting steel the name Stainless Steel. In 1916 he was granted patents in the USA and a number of European countries.

Wikipedia:

In the beginning stainless steel was sold in the US under different brand names like "Allegheny metal" and "Nirosta steel". Even within the metallurgy industry the eventual name remained unsettled; in 1921 one trade journal was calling it "unstainable steel"

It could be that the name "Stainless steel" could not be used by other companies because it was patented at that time. So Darwin's "Patent Cobalt-Chrome Steel" could very well mean "Patent Cobalt-Stainless Steel" in todays language.

The composition also looks pretty suitable, as Scientific American article sums it up nicely:

Stainless steel contains iron, chromium, manganese, silicon, carbon and, in many cases, significant amounts of nickel and molybdenum.

Of course, we would have to know for sure that blade's Darwin's Cobalt Steel and Patent Cobalt-Chrome Steel is the same material, as you said.

But we know that this IS cobalt steel one way or another. And talking about cobalt properties - Wikipedia mentions that cobalt is added in order to have Cobalt High Speed Steels (HSS). What it does is:

The addition of cobalt increases heat resistance, and can give a Rockwell hardness up to 67.

It also mentions 2 cobalt steel types:

M35 - M35 is similar to M2, but with 5% cobalt added. M35 is also known as Cobalt Steel, HSSE or HSS-E. It will cut faster and last longer than M2.
M42 - M42 is a molybdenum-series high-speed steel alloy with an additional 8% or 10% cobalt. It is widely used in metal manufacturing industries because of its superior red-hardness as compared to more conventional high-speed steels, allowing for shorter cycle times in production environments due to higher cutting speeds or from the increase in time between tool changes. M42 is also less prone to chipping when used for interrupted cuts and costs less when compared to the same tool made of carbide.

And Darwin's specialty during 1930s was high grade steel tools, "Cobalt Fastwork" Hacksaw Blades, "Darwin 505" Cobalt Tungsten High Speed Steel, "Vanadia" Hacksaw Blades.

So this razor must have a really good blade, even compared to regular stainless steel - harder, tougher and resistant to wear.

Originally Posted by Rigensis

So this razor must have a really good blade, even compared to regular stainless steel - harder, tougher and resistant to wear.

It certainly must have a blade suitable for shaving with for sure. There are quite a few steel alloys the are quite suitable for making a straight razor blade.

Stainless steel's main advantage in straight razor blades is that it rusts at an extremely slower rate that other steel alloys to the point that it appears to be rust free for the most part.

You can make a blade that is really too hard and too resistant to wear. Again not an expert but anything much above a Rockwell hardness of 62, from what I have read, can make the blade a bear to hone and subject to being prone to chippy edges. There is a balancing act in making a steel alloy suitable for straight razor blades to get the right combination of characteristics required.

You might be better off to post any questions on Darwin Patent Cobalt Steel in this sub forum http://straightrazorpalace.com/forge/ . That is where the blade makers hang out and they might have better answers being used to working with various steel alloys.

Bob

Originally Posted by BobH

Make that two, I am working on a 7 day set.

Bob

I too have a Darwin cobalt steel straight Blade Razor which I inherited. My grandad received this Blade & a watch for 25yrs service when he retired from Darwin of Sheffield. Yes that's right my grandad worked for the company that produced these beautiful crafted razors. The 1 I have has a black handle and has never been used and is still in its original box. It is also for sale unfortunately as I need the money to put towards my father's gravestone. If u would like to see pictures and discuss buying it then please don't hesitate to contact me even if u just want to look at the pics I don't mind.

If you want to know the alloy composition you could have an X-ray fluorescence (XRF) analysis done. Big scrap metal dealers have portable XRF analyzers and would probably do an analysis for a small charge. They use these analyzers to sort scrap into categories.

Did you clean it up or buy it in that condition. Looks good. Blades like that with a full heel seem to too often have been chipped too high to hone out.
Not familiar with the name, but you would think with a name like Darwin more of them would have survived.

I didn't buy it. It was handed down to me. It was given to my grandad along with a smiths watch when he retired from working 25yrs for Darwin (company that made the blade). My dad inherited it & then I did. It's never been used. Got the original box it came In and never been cleaned don't need to coz like I said never been used. It's still as sharp as the day it was made. Beautiful blade. Shame I gotta sell it but the money I get for it is going towards my dad's headstone. Thank you for Ur comment JP5.
Maladroit I don't need to go to them lengths to find out as it's made from cobalt steel. But thanks for the suggestion much appreciated.