Etching with iron(III)chloride hexahydrate

[Martin Lubojacky]

Hello, I wonder If I may ask for an advice:
How concentrated should the solution be ? How long time should the blade be plunged ? When removed from the bath, should the blade be slightly (by cloth) repolished again ? Any potential risks ?
Thanks
Martin

[kai]

Hello Martin,

Please search this site for several detailed tips.

Just a few comments:
Concentration is not so critical but make sure you don't overdo things! Evenly wipe the solution over the blade (repeatedly - the reaction is usually pretty fast though). Start with a weak solution and increase the concentration if needed.

FeCl3 is a strong, agressive etchant: apply as short as possible, neutralize very carefully, and wash off generously. Make sure the etching solution touches the blade only and protect all fittings!

Ferric chloride will dull a steel surface quickly. After a first exploratory etch, one stragegy is to repolish by hand and follow up with a very quick final etch.

Any traces left on the blade or other parts will keep being corrosive forever - be very careful with applying the stuff and, especially, removing the etchant completely.

Regards,
Kai

[A. G. Maisey]

Good practice is to kill the etchant with a slurry of bicarbonate of soda.

Blade must be absolutely clean and free of oil or grease prior to commencement.

Warm temperatures speed reaction.

[Martin Lubojacky]

Thank you both.
I hope covering of gilding with zapon lacquer will be sufficient.
Is there slight polish necessary after the final short etch (and neutralization), or this final polish would destroy the optical result ? Thank you.
Martin

[Ferguson]

I have etched a lot of blades, but I'm no expert. My method is in this thread.

Etching

I have read that doing the first neutralization with vinegar converts some chloride ions to a non corrosive form. (I'm no chemist) I then rinse and neutralize with ammonia, then with a slurry of sodium bicarbonate.
I've never had any corrosion or rusting issues doing it this way.

Good luck sir!

[blue lander]

How polished should a blade be before you etch it? Does it need a mirror finish?

If you etch a blade that's been cleaned and not polished and no pattern emerges (steel just turns uniformly gray) is it possible that you'd get a pattern if you put a mirror finish on the steel and tried again? Or would you at least see some evidence even without the polishing?

[kai]

How polished should a blade be before you etch it? Does it need a mirror finish?

No polish needed per se - it's a matter of taste or what the traditional approach would be for a given culture/piece.

If you etch a blade that's been cleaned and not polished and no pattern emerges (steel just turns uniformly gray) is it possible that you'd get a pattern if you put a mirror finish on the steel and tried again?

Quite rare but possible: If a blade has been polished with power tools the laminations at the surface may be obscured. If accumulating surface rust has not eaten through this "smear" layer the laminations may still not visible. Repeated etching and polishing (by hand) may help to expose any laminations though.

Regards,
Kai

[Jens Nordlunde]

As it has been mentioned, FeCl3 is very agressive, so you have to be careful.
Some time ago this was discussed, and some suggested anything from pineapple juce to lime juice.
I find that ferrycloride is very good, but maybe you should try it on a blade of less value, so you know what happens, as you can always remove it, but just to make sure you know how it works.
Make sure you have the neutralisers at hand before you start.
You may end up with a blade slightly yellowish, but this can be removed by adding acid free oil and work the blade over with very fine steel wool - very gently.
Good luck
Jens

[kai]

Hello Steve,

Yes, your etching results are certainly fun - keep them coming!

I have read that doing the first neutralization with vinegar converts some chloride ions to a non corrosive form.

No, chloride ions will need to be extensively rinsed off regardless of any intermediate treatment.

The vinegar may help to remove excess iron salts (if you leave it on for too long you'll reduce the contrast of the stain though) and, thus, avoid the yellowish color which is often visible in blades treated with ferric chloride.

I then rinse and neutralize with ammonia, then with a slurry of sodium bicarbonate.

I'm not convinced it is really necessary to do both. Ammonia may have advantages in reaching crevices in pitted/cracked blades but you'll need to rinse such blades extremely carefully anyway. Ammonia chloride residues are moderately acidic while sodium chloride is neutral; this is pretty academic though since you need to work with excess ammonia or sodium bicarbonate, anyway, and both solutions are alkaline.

Once you have neutralized any traces of acid, you really need to rinse away any salts/ions. Deionized water, lots of DI water!

Regards,
Kai

[kai]

Hello Martin,

I hope covering of gilding with zapon lacquer will be sufficient.

Well, gilding on an iron blade (koftgari and even inlay) changes the game dramatically: Be very, very careful! If in doubt, better do nothing or just stabilize any active rust rather than doing harm by irreversible actions.

If a blade with koftgari/etc. has not been cared well for, chances are that you'll loose some or even all of the gold by removing rust that may have developed below the koftgari and even next to the inlay.

Please post close-ups of the piece of interest and I'm sure the specialists can give you some pointers. This really needs to be explored on a case by case basis; and with lots of patience and expertise!

Is there slight polish necessary after the final short etch (and neutralization), or this final polish would destroy the optical result ?

Again, this depends on several variables - Jens gave already an example.

In general, polishing after the etch will result in lower contrast; buffing a protective topping of renaissance wax may be enough to get the blade shiny. In a perfect world, you'd not have to polish again if the etch was spot on: better etch a bit too shortly rather than too long resulting in a dull blade.

Regards,
Kai

[spiral]

Protect the kofgari areas with wax,{melted then solidified.} then just etch the unprotected areas with a repeated brush wipe, rather than risking dipping.

I don't like Fc myself, I prefer sulphuric,, lemon, vinegar & pineapple mostly, but FC is very popular on this forum.

Only etch when you have uninterrupted time, turn your phone off & don't answer the door!

spiral

[Martin Lubojacky]

Thank you all for your (for me) very important advices and Good Lucks !

Unfortunately, miracle did not take place and I found out that the blade was made of, I would say, normal steel (there was some parallel lamination, but always accompanied with relatively deep pitting, so I better polished it again after three very quick attempts.

Very important was the piece of info from Spiral "to have uninterrupted time, turn your phone off & don't answer the door!". But when I cut my finger and the result was not "slightly yellowish", but "reddish", it was like phone ringing and at the door knocking etc altogether.

This is also the sword from this thread: http://www.vikingsword.com/vb/showthread.php?t=19145
And Here are the requested close ups - but as I said, no "damascus".
Thanks once more
Martin

[spiral]

Originally Posted by Martin Lubojacky

Very important was the piece of info from Spiral "to have uninterrupted time, turn your phone off & don't answer the door!". But when I cut my finger and the result was not "slightly yellowish", but "reddish", it was like phone ringing and at the door knocking etc altogether.

And Here are the requested close ups - but as I said, no "damascus".

Ahh that's only flesh though... that heals... the blade is what matters!

Mmmm so the hilt straps are re built by the same chap who made the scabbard it seems?

If blade was mine Id give it a little go with pineapple juice to see if that brings anything else out.... not all etchants work equally on all blades in my experience.

spiral