Blade protective treatments - the good, bad, and ugly

[peshkabz]

I have been picking up several knives lately (sound familiar? ) that have several blade treatments. Two are bead blasted, the other two are Black Teflon. All are large CRK&T Kaspers. One each for me, one each for my dad. While I am happy with the appearances, I found out the bead blasted blade quickly looks 'less attractive' if you touch the side of the blade to your sharpner (out of sloppiness in my case - Gave the untouched one to my dad quickly before I screwed that one up). I love the looks, but cringe at the scratching I left on the blade of the one bead blasted blade. I would buy another for the appearance, but.... now I look at scars - no - character.
I wonder if some of the treatments are cost savings(?) or have benefits I don't know about. The Black T I have heard many good things about from the gun world - but lets stay with knives here...

So, you in the know, what are the most common blade treatments out there?
What are the benefits of these treatments?
What are the cons?
What are your personal preferances?

This ought to be informative for many........


(I want to keep this positive and informational - none of this is to bash my Kaspers - I love 'em!)

 

[Quiet Storm]

I don't think that I'm "in the know", but anyway, here are my 0.02$.

Bead blasted (in many aspects similar to sand blasting, the latter sports a finer finish though) surfaces are non-reflective, hide little imperfections on the unfinished blade pretty well. Their big drawback is that they're prone to rust because of the tiny dents in the surface that store fluids.

Teflon-coated blades are also non-reflective, but they tend to scratch easily and a scratched blade with a Teflon coating doesn't look very nice.

Boron carbide coated blades are more impervious to scratches, but that stuff is expensive.

Polished blades are shiny and they resist rust very well because of their even surface that doesn't trap moist. Even small scratches are very noticeable on mirror polished blades.

A satin finish can come in many variations (dependant on how coarse the sandpaper used to finish the surface was). They are generally middle of the road in regards to performance (not really non-reflective, but it resists corrosion pretty well and scratches are not too obvious).

There are a lot of other surface finishes (e.g. stone-washed), but most of them are just variations of one of the above-mentioned variations.

Try using the search function for more information, this should provide you with a lot of worthwhile threads.


I personally like both satin finished and sand blasted blades.

 

[niagaraguy]

Interesting... Where does one go about getting a Boron Carbide coating? Would I be able to do this to a native?

Trevor

I'm located near Toronto btw

 

[Walking Man]

QUOTED "Bead blasted (in many aspects similar to sand blasting, the latter sports a finer finish though) surfaces are non-reflective, hide little imperfections on the unfinished blade pretty well. Their big drawback is that they're prone to rust because of the tiny dents in the surface that store fluids."

This is actually not the case.
Bead blasting is SUPPOSED to be done with hard beads that actually "micro-forge" the blades surface and will prevent rust.
HOWEVER!!!! Don't trust it.
Too often (most production models, I think) A maker will do it wrong and it's just like sandblasting, which WILL create lots of microcrevises where rust WILL spread like wildfire.

I'm not an expert, but this has brought up a couple good questions
1) How can you tell GOOD bead-blasting from BAD??? (if possible)
2) How often does BAD bead blasting occur and who does it???
-Walker

 

[PhoulPlae]

I asked for a listing of all (or the most common) coatings and finishes a while ago but got no response, so I did some research...

There is a difference between finishes and coatings. Finishes are the physical structure of the outer surface of the metal.

Bead-blasted, sand-blasted, stonewashed, satin, mirror polished, etc. are all finishes. The -blasted finishes are my least favorite. They are designed to hold onto a coating or oil, etc. because of the uneven surface, not to be used as a final finish. Walking Man also has some good points. Satin, stonewash, and mirror polished finishes typically have better corrosion protection and are real "final" finishes.

Coatings may or may not protect the blade. Some of the softer (prone to wear) coatings are:

-Teflon: adds lubricity and protects from corrosion. Easily scratched or worn off.

-Epoxy powder coat: prevents corrosion where covered. More durable than teflon, BUT flakes off under hard use.

-Kal-Gard GunKote: protects from corrosion, adds lubricity. More durable than teflon or epoxy, but still wears out under abrasive use(but doesnt chip or flake)

-Parkerized (zinc phosphate?)- cheap "coating" found on some military knives. The only purpose is to subdue reflection and enhances adhesion of oil or other coating.


-Black Oxide (or blueing) is not a coating but a process that oxidizes the outer surface of the steel. This is as hard as the steel before, and doesnt add anything, just chemically changes the outer layer. The steel is turned black, and minor corrosion protection is gained. The steel will still retain whatever finish it had before. (A mirror polished blade will be smooth black, bead blasted will be matte)

Some "high-tech" coatings chemically deposit a coating harder than the steel itself:

-Titatium Nitride: Hardness around 80+ Rc, matte texture, protects from scratches, and abrasion, with minimal corrosion protection. Different variations (Ti CarboNitrider, Ti ZirconiumNitride) will give different colors, usually Black or Gold. Can wear off, but not easily.

-Boron Carbide (DiamondBlack): Hardness greater than TiN, 90's Rc. Virtually impossible to wear off unless you damage the metal itself. I believe it is semi-porous, but still offers some corrosion protection benefits. Usually black, it takes the appearance of how the blade surface was finished.

-Diamond Like Carbon: The "Ultimate" blade coating, made of 3 separate layers: First is Chromium Nitride, which acts as the rust barrier, for very good corrosion protection. Second layer is Tungsten Carbide, adding wear resistance. Third layer is Diamond Like Carbon, hence the name, which is like a solid carbon deposit, making it very hard and smooth. Hardness is comparable to Boron Carbide, but Boron Carbide may be slightly harder, with DLC have greatly increased corrosion protection.

 

[peshkabz]

Originally posted by Quiet Storm

Teflon-coated blades are also non-reflective, but they tend to scratch easily and a scratched blade with a Teflon coating doesn't look very nice.

Does this mean the teflon usually scrapes easily to the metal surface, or discolors the finish.
I had read somewhere that even if the teflon wears down to little more than a stain, it still protects and lubricates, as it empregnates into the surface...


what to you folks think of this...?

 

[Walking Man]

It scratches all the way off.
It's the black, kind of crusty, coating you see on many knives.
Almost all of the least expensive coated knives use Teflon.