Strange Marks On Blade

Brendan

Brendan

Joined
Feb 13, 2002
Messages
3,679
I just bleached one of my khukuris to dissinfect it so I can use it in the kitchen and there are all these weird spots on the blade (both sides). Almost looked like mold when I took it out the bleach, gave it a wash with dish washing liquid and the spots are still there but less prominent (various shades of colours).

Cant think what this is, there was nothing on the blade when I put it in the bleach and i washed it before, surely if it affects the metal the whole blade would mark not just in spots. Maybe it's blood residue from the puja ceremony, maybe it's from the hardening process - who knows.

Anyone have the answer ??

B
 
Chlorine will etch your blade. WHy it etched it only in spots, I couldn't say.
 
bleach....:barf: :barf:

Bad for blades and handles. What you have is a mild surface etch. Do the spots correspond to any recent wear-n-tear?

The best way to get the spots off will be to polish it - just like you would your silverware.

Next time, use soap and very hot water. That will work better than bleach. Heck, lemon juice will work better than bleach.

(sorry to come crashin' down on ya, bro)
 
My bad !!

Come down on me as hard as ya like - it's how we learn I suppose !!

B

Thanks for help Pen !
 
next time. A short (ie too short) time in an etchant will produce spotty finishes. Happened on a biltong I was etching, then I put it back into solution and it etched an even non-glare gray (with a darker gray temper line--martensite)

Keith
 
It was watered down - would never straight bleach it - so if I out it in for longer it will etch the hole thing !!!

B
 
Pen is right, but be careful of lemon juice (or any citrus). That'll eat steel like you won't believe. It is one of the many things used to produce "antiques".
 
Bleach (Sodium Hypochlorite) + iron ==> Ferric Chloride & ?Sodium Chloride (salt)

That's the etchant, and salt promotes oxidation/rusting.
 
ddean is right, bleach in it's liquid form is an acid, a mild one but still an acid that will react with iron and other metals producing the stain you describe. Why it stains in one spot before another is a product of many factors of which particular surface condition, heat difference, ion dispersion [this can be a factor when the bleach is first diluted and doesn't have time to disperse evenly throughout the solution], and others that a chemist could more readily tell you. What you have done is enter the world of inorganic chemistry and completed your first experiment. By this thread we can see it has raised more questions for you than answers. Congradulations and welcome to the world of chemistry.
 
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