Concretion

[Christoph1945]

I have a number of small iron targets that are encased in concretion. It looks to be formed from rust, sand, pebbles, and shells. It is as hard as nails and an electric engraving tool or scraper will not shift it. What is the best way to remove concretion; without dammaging the target encased within it?

[fv1620]

I find putting it on a hard surface then hitting it with a plastic headed hammer works well. Start with low power hits until it shatters away often leaving the object quite cleanly.

It is amazing how small the object can be with all this stuff on it. No doubt some shrinkage has occurred by the outer surface taking part in the chemical reaction.

[Christoph1945]

I find putting it on a hard surface then hitting it with a plastic headed hammer works well. Start with low power hits until it shatters away often leaving the object quite cleanly.

I tried the hammer technique on some of my first finds and it worked rather well but I was looking for something gentler; just in case the object was more fragile. I thought that maybe electrolysis, but perhaps the concretion would set up a resistance to the electric circuit.

What do you think?

[fv1620]

I've never tried electrolysis. My other hobby is restoring military vehicles where reclaiming grotty bits is a necessity. Here is a thread from a Canadian military vehicle site that may be of interest.

http://www.mapleleafup.net/forums/showt ... ectrolysis" onclick="window.open(this.href);return false;

[Christoph1945]

Here is a thread from a Canadian military vehicle site that may be of interest.

http://www.mapleleafup.net/forums/showt ... ectrolysis" onclick="window.open(this.href);return false;

Thanks for the site link; I have had a quick look and it is very similar to a setup that I have seen on the "Friendly Metal Detecting" site. I image that the system would work very well on your vehicle parts. I fully intend building a similar unit for derusting my finds but had hoped that someone out there knew of a quick and easy way of getting the concretion off before derusting.
( Not the hammer )

I will go ahead and try electrolysis on one or two pieces and see what effect it has on the concretions. Perhaps if I set up a multi meter in the circuit; I will be able to see what ( if any ) resistance the concretion causes!

[Wansdyke44]

What about using a dremel drill?

[DougieH]

What about tightening in a vice?

Doug

[Remus]

What about tightening in a vice?

I agree. Sandwich it first between two pieces of wood, apply pressure slowly. If you hear a crack or see anything flaking off stop and examine it. You can change it's position to try pressure at various points - or even leave it in the vice overnight.

[Butty]

Freeze/thaw?
Stick it in a freezer to get cold then pop it in a hot oven.

[fishy]

Freeze/thaw?
Stick it in a freezer to get cold then pop it in a hot oven.

Thats probably a great way to loosen things up.

[Christoph1945]

Thanks for all the suggestions guys. I will now set about trying out a number of them and see how things work out. I have six similar iron items to work on and will shortly post some pictures on this thread and also report on any progress.

[Christoph1945]

Spending some recent time detecting at Talacre in North Wales, I have been finding plenty of junk and some WWII munition items. Plenty of copper jacketed bullets; both 50 caliber and 303's.




The last time that I was there, I noticed a number of iron items encased in concretia kept turning up. All the items were similar in weight and size and had a generally teardrop shape to them. Following one of the above suggestions, I decided to try using a vice on one or two and see what happend.

By gently applying pressure in a vice, I found that the items cracked like an almond nut and a small bullet shaped piece of iron dropped out. When I later gently shook several of the others; one could hear something rattling inside. I am guessing that they may have been armour piercing bullets from WWII. What do you think?

Any information and advice would be most welcome.

[william holmes]

ive often found when breaking 50 cals out of concretion that the concretion was formed of the of the armour piercing core .with out the steel core there i guess it would just not happen but i have found 303,s ball rounds in concretion but that is verry rare

[Christoph1945]

Thanks William, initially I didn't have a clue what the items were; I just thought that they were bits of scrap. Whilst working the same area, I dug out a modern spoon and fork that were sitting a good foot deeper than the WWII stuff.

[william holmes]

its strange how bullets settle at a cretain level