A Hard Particle Is Good To Find: The Diamond Vs CBN Debate – How To Make Your Straight Razor Sharp

It is a truism of marketing that when a market-space starts becoming crowded with product, someone is bound to come out with something they claim to be “New & Improved” to attempt to capture greater market share. You are seeing this happen right now in the razor and knife honing market. There are quite a few products on the market, including ours, which utilize diamonds as the primary abrasive to perfect your blades. With the market becoming crowded with various brands of diamond sprays, each using different formulas and quantities of those magic microscopic gems, at least one clever vendor has come out with something new – CBN.

Actually CBN isn’t exactly new. In fact, it has been around since the 1970’s. But what you probably want to know is if it offers any real advantages over the tried and true diamond slurries. That is the question that this short article will answer.

It might be useful to start out with a basic knowledge of the stuff. CBN, or Boron Nitride Crucible is a laboratory manufactured material which has the same crystalline structure as diamond. It is 2nd only to diamond in hardness, which makes it harder than all known metals.

But does it have an advantage over diamond slurries? Surprisingly it has two, but there is a caveat to this statement, so please read to the end.

In situations with large amounts of friction, diamond, which is nearly 100% carbon, can form an affinity for the carbon in the steel. This can cause the diamond particles to break down and lose their effectiveness. This problem does not occur with CBN. Secondly, diamond suffers from a massive loss in hardness when it gets hot, making it effectively softer than CBN under these conditions.

Sound like a problem, doesn’t it? So how hot does the material have to get to give CBN the advantage? Pretty toasty, as it turns out. The metal would have to achieve a temperature of 700 degrees Celsius (1,292 degrees Fahrenheit) for the performance of diamonds to degrade to an effectiveness below that of CBN. I don’t know how many “X” strokes I can do on a hone or strop in one minute, but I believe that I have a very long way to go before I am going fast enough to generate 1,292 degrees of heat. Of course, by then my strop would have long since caught fire:-)

Yes, I have taken a moment to poke a bit of fun at the issue, but there is a serious point here. You, the consumer, are being presented with an ever-increasing array of choices. This is both a blessing and a curse. You can get some excellent values and you can also get mislead. There is no evidence to demonstrate that, all things being equal, CBN cuts faster or in any way performs better than diamond….unless you are working at those very high temperatures or very high levels of friction which create them. You needn’t take my word for it; research it for yourself. Any decent article on the advantages of CBN over diamond will mention heat/friction as the primary factor in its superiority.

That said, I would expect the performance of CBN slurry spray to be no worse than that of diamond sprays – although at $32.95* per 2 oz bottle of CBN vs. $14.95 for a high quality diamond slurry spray, the price may give you pause.

As I have said countless times – the only way to find what work for you is to try the product. That is one of the reasons that we keep our prices affordable and you armed with the facts.






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