Your thoughts on blade finish

[OconeeDan]

I was playing around with scraps of steel, and ferric chloride (used to etch damascus steel).  I took a small scrap of D2, on one side I mirror polished it.  On the other, I left it satin.  On each side, I jeweled a small area.  So I had 4 different finishes on the scrap.  
Then, I submerged in ferric chloride solution for about 10 minutes, rinsed off, and ...
The scrap now has a very flat grey finish, basically etched.  There was no hint that there were ever different finishes on it, the entire piece was very consistant.
I guess this is actually cold parkerized?  And my guess is that this would be very protective finish, both as a finish and also by holding a preservative such as a light coat of oil.
I hit the edge on a grinder, to show that the sharpened edge would be bright silver on a gray blade.
I will tell you one thing, it would camoflauge any imperfections in a blade finish, although this was not my goal.
Would like your thoughts on this.  Does this weaken a blade (my guess is no)?  Is this a desireable finish to you?  If any of you have done this, does this make a very durable finish as I am guessing?
Thanks in advance, Dan
 

[Leftieshot]

Is that piece of scrap hard or annealed?  You've got my gears turnin now.  How strong is that acid?  From a health stand point?

[OconeeDan]

No, that scrap has not been hardened, but it should make no difference in the appearance or finish.
That acid is about a 25% solution, tastes real bad.  :D  
Seriously, it is acid and should be treated as such.

[robtattoo]

Cooo! Funny how D2 goes such a matt grey colour. I've etched a few of my blades for folks wanting a 'tacticool' look & 01 comes out black! One thing I did notice, contary to what you've mentioned actually, is that the smallest imperfection seems magnified! Wierd, huh?
Would you mind, if it's not too much trouble, doing the same thing on a hardenes & HT'd piece of D2 & 01 for comparison. I don't have access to any D2, just 01 & W2.

[Jeremy]

Like Rob, I've found that the smallest imperfections are magnified, especially with that long of an etch.

I etch in ferric chloride all the time to get contrast on differentially heat treated blades:
   
   

The above were all 10-15 second etches followed by rubbing the whole blade out with Flitz.  

Coming out of the acid they look like this:
    with the hardened section being black.  After a minute or two with some Flitz it looks like this
   

The acid bites into the hardened steel differently than the softer steel.  The oxides formed polish off the hard steel MUCH faster.  All the O1, 1095, 1080 and 5160 I've played with all etch the same: only the soft steel comes out grey.

[OconeeDan]

Rob and Jeremy, I don't have any O1, so maybe I need to try it later.  
Don't know why imperfections were magnified with your experience, but in this little test, the etching blended everything together nicely.  You have to look HARD for imperfections afterward, everything was frosted gray and was very uniform.
Dan

[Leftieshot]

I think its because the test piece wasn't hardened.  Its been my experience in the industry that our hardened die steels react differently to surface treatments vs. being annealed.  If I had a piece of hardened D-2 I'd send it to you to test.  All my blades are A-2.

[Lin Rhea]

Dan,
      Take another test piece and pass a 60 0r 120 or even 220 grit across it a few times and etch it. It's my experience that the scratches dont blend because of the etch, they are seen more clearly. Also, the scratches combined with a hardened edge cab make little shadows in the temperline.
    It's true that some imperfections can be disguised by etching, but most not. Your testing is enlightening and admirable. Lin