FeCL Question

[bbulat]

Ok, did the FeCL etching and got the color I was looking for. However, after oiling twice, black residue continues to slough off the blade. Even if I wipe the blade dry, the cloth shows residue. Did I miss a final step or is there something I can do to prevent this?

 

[JStrider]

I havnt done any etching myself, but I'm pretty sure your supposed to gently sand it with a really high grit sand paper...

also did you neutralize the acid? maybe its still eating away at the blade? I would dip it in ammonia or rub it with a baking soda paste, at least as a safety measure till someone more knowledgable comments.

 

[kronckew]

FeCl3, to simplify the reaction, produces essentially hydrochloric acid when mixed with water. it must be neutralized with a base, like ammonia, baking soda, or lye (sodium hydroxide) or it will continue reacting with the metal for a bit after you remove it from the solution until it is used up or neutralized. after neutralizing, wash with proper soap & a soft sponge afterwards until the black stuff stops coming off, followed by a final rinse in very hot water, drying and oiling. proper lye based soaps will assist in this as they are somewhat basic after being made, unlike 'cleansing bars' like 'dove' made of synthetic chemicals which tout their chemical neutrality. they can still be used, but may take more washing and more water to flush away the bad stuff.

 

[Dave Rishar]

Even after neutralizing and polishing, you're going to have some oxides left. You'll notice them the most when you're oiling. Don't sweat it, it's nothing. It will go away eventually.