Chemical cleaning of brass-iron-fuses

[panzergraf]

Hi guys, after years of just reading I'm going into action

My son and I are collecting the remains of the battlefields of WW I - but no, we don't rob historical places with detectors. We just collect the clearly as inert identifiable remains dug out by farmers in the fields or at their dirt roads.
So recently some fuses found their way to our small collection. And here the problem starts:
Normally I clean the objects coverd with heavy rust with brass wheels or sand-blasting, later or if the pice is not too corroded by using a solution of citric acid in water - I normally prefer the latter, because it is the smoothest way for the material. That works fine for iron or iron and copper as driving bands. Now I got a problem with the fuses made of a mixture of brass and iron. There is an electro-chemical reaction in the brass, dissolving the copper out of the material and creating a copper-overlay over the non-iron parts, while the deoxidation/reduction of the iron seems to be slowed down.
Has somebody an answer for this problem, or am I just overreacting?
Thanks a lot for helping an greetings from Germany!

 

[AMMOTECHXT]

Hi Panzergraf and welcome to BOCN.

I think the problem you describe is dezincification - acid dissolves the zinc from the brass to leave the copper. I wonder if the dissolved zinc attaches to the steel / iron? All I can suggest is that you limit the time you leave the fuze in the acid and this should reduce the depth to which the brass loses the zinc. I recently used some household vinegar to clean some 25 Pounder Smoke BE driving bands that had rust from the shell still attached. After about 24 hours in vinegar the rust had been softened and made loose in places where it was not very thick. It was then easy to scrub off the rust with a wire brush and this has made little difference to the surface of the metal. I have previously cleaned brass fuzes in vinegar but, as you experienced, the zinc was leached out. Patient cleaning with soft cloths and a brass polish eventually restores the brass colour by removing a very thin layer of copper. I once made the mistake of pouring coca cola or equivalent into an aluminium container to use as a bath for cleaning found items and left the liquid in for a week or more. It ate through the aluminium.

Best wishes from XT in the UK.

 

[botcheg]

Hi guys, after years of just reading I'm going into action

My son and I are collecting the remains of the battlefields of WW I - but no, we don't rob historical places with detectors. We just collect the clearly as inert identifiable remains dug out by farmers in the fields or at their dirt roads.
So recently some fuses found their way to our small collection. And here the problem starts:
Normally I clean the objects coverd with heavy rust with brass wheels or sand-blasting, later or if the pice is not too corroded by using a solution of citric acid in water - I normally prefer the latter, because it is the smoothest way for the material. That works fine for iron or iron and copper as driving bands. Now I got a problem with the fuses made of a mixture of brass and iron. There is an electro-chemical reaction in the brass, dissolving the copper out of the material and creating a copper-overlay over the non-iron parts, while the deoxidation/reduction of the iron seems to be slowed down.
Has somebody an answer for this problem, or am I just overreacting?
Thanks a lot for helping an greetings from Germany!

Perhaps you could use a printmaking technique where you coat the areas of a metal plate with a "resist" such as lacquer leaving areas open to the acid-etch bath. when those open areas are sufficiently etched, the lacquer is removed with solvent and the plate is ready for printing.
So, coat the brass area with an acid proof coating like lacquer, then, after the soaking in an acid bath you can remove the coating.
Bill

 

[panzergraf]

Hi Panzergraf and welcome to BOCN.

I think the problem you describe is dezincification - acid dissolves the zinc from the brass to leave the copper. I wonder if the dissolved zinc attaches to the steel / iron? All I can suggest is that you limit the time you leave the fuze in the acid and this should reduce the depth to which the brass loses the zinc. I recently used some household vinegar to clean some 25 Pounder Smoke BE driving bands that had rust from the shell still attached. After about 24 hours in vinegar the rust had been softened and made loose in places where it was not very thick. It was then easy to scrub off the rust with a wire brush and this has made little difference to the surface of the metal. I have previously cleaned brass fuzes in vinegar but, as you experienced, the zinc was leached out. Patient cleaning with soft cloths and a brass polish eventually restores the brass colour by removing a very thin layer of copper. I once made the mistake of pouring coca cola or equivalent into an aluminium container to use as a bath for cleaning found items and left the liquid in for a week or more. It ate through the aluminium.

Best wishes from XT in the UK.

Hi XT,

thanks for your reply and your nice welcome.

Thats a new point of view, I first tought about a reaction of the copper in the brass because copper was all I recognized. But you are right, there is zinc, too - you gave me an enlightenment. Cu and Zn should be in a metallic form in the brass, so the dissolution of Zn as the less precious metal (I hope its the correct word in english, I mean the electrochemical order) into Zn2+ seems logic.

No, the Zn does not form a layer on the iron, it is just a reduced reaction of reduction of Fe2+/3+ to Fe - perhaps because the reaction in the solution is not between acid and iron, but an electrochemical redox-reaction between zinc and iron. All logic, because Cu as most, then Fe are more "precious" (it sounds so gollumnesque) than Zn, which explains the order of dissulution, and that there are no problems with driving bands made of pure copper.

Perhaps I will try electrolysis with the fuse as the anode (electron-donator). I will have a try and report.

A soft polish restores the brass surface, so no harm done. Interesting is, that first comes the remains in form of a copper-layer, then the silver shining layer of Zn, and at least the brass. The layers are extremely thin, but recognizable.

Thanks for your help an best wishes from Germany,

panzergraf

 

[panzergraf]

Perhaps you could use a printmaking technique where you coat the areas of a metal plate with a "resist" such as lacquer leaving areas open to the acid-etch bath. when those open areas are sufficiently etched, the lacquer is removed with solvent and the plate is ready for printing.
So, coat the brass area with an acid proof coating like lacquer, then, after the soaking in an acid bath you can remove the coating.
Bill

Hi Bill,

thanks for your reply. I will give it a try, too. The problem is, that after detonation the fuses are in a bent shape. The bottom side, facing to the charge, is divided into parts of iron and brass from the fuse, that form a happy melange after doing their job. So, in all the rust and dirt, even after cleaning in the ultrasonic bath, it is nearly impossible to divide the zones in which is which. And it seems that the theory of electrochemical order and the preferred reduction of zinc is correct, so the smallest, not covered part of brass automatically leads to a electrochemical reaction exactly at this point.
But as I said, I will give it a try, too, and inform you about the results.

Thanks for your help an best wishes from Germany,

panzergraf