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Didn't see any threads on this so here goes - my son and I found a cylindrical iron object in the coral off the fort at the naval dockyards in bermuda - looks somewhat like the base of a small cannon/boat gun, or maybe some kind of iron pot/container. Pretty heavily encrusted with coral. about 18 inches long about 8 inches in diameter and 30-40 lbs. It has been out of the water for 5 days.
Here's the question - we want to clean it up so we can see what it is, how do we go about this? Tools available are the usual hand tools, car wash (lol), can borrow a pressure washer, but would like hear from the folks that actually know how to do this before we do something stupid
Put the artifact in freshwater now. Letting it dry out can damage or even ruin it. To clean it I would recommend using an electrolysis setup. These are relatively cheap and easy to set up and will effectively remove the salt from the artifact. If you don't remove the salt the artifact could be ruined when it drys out. There are lots of websites that describe how to set this up. However you are looking at atleast 8 months of treatment, maybe more.
An alternative method is to find a stream to put it in to leach the salt out, but this will take even longer. If it is small enough you could put it in your toilet tank. I currently have a couple of pieces soaking there (don't tell my wife).
Whatever you do, make sure it is safe and always keep it wet until treatment is completed.
No problem. I would like to see some pictures if you take any. I forgot to tell you to remove as much of the encrustation as you can before putting it in water. Hope it turns out well. It sounds like a cool artifact.
To clean it I would recommend using an electrolysis setup. These are relatively cheap and easy to set up and will effectively remove the salt from the artifact.
First off, electrolysis is NOT for removing salt. Electrolysis is the use of electric current to reverse the oxidization from metals. Many electrolysis users even use :11: saltwater :11: as a conductive agent because fresh water will not conduct current.
Now that is cleared up, you are on the right track. Soaking in fresh water to leach out the salts is VERY time consuming, but needed. Museum conservators will soak iron cannons for more than a year, with daily water changes.
I also see no problem with whacking and chipping away the coral encrustation. Saw a show about ocean recoveries where they whacked away at cannons with 2 pound mallets to break away it's casing of 300 years of ocean.
In addition to removing rust, Electrolytic reduction cleaning (what I have been calling electrolysis) WILL remove chlorides (salt) from the artifact. The following paragraph is taken directly from the Nautical Archaeology Program, Texas A&M University (http://nautarch.tamu.edu/class/anth605/File10a.htm) publication METHODS OF CONSERVING ARCHAEOLOGICAL MATERIAL FROM UNDERWATER SITES by DONNY L. HAMILTON. The last sentence says that chlorides are drawn from the specimen by electrolytic attraction.
The essence of the technique involves setting up an electrolytic cell with the artifact to be cleaned as the cathode. An electrolytic cell consists of a compartment or vat with two electrodes, the anode and the cathode, and contains a suitable electricity-conducting solution called the electrolyte. An electric current from an external direct current (DC) power supply is applied to cause oxidation and reduction. The anode is the positive terminal of the electrolytic cell, to which electrons, negatively charged ions, or colloidal particles, travel when an electric current is passed through the cell. Oxidation occurs at the anode and oxygen is evolved. The cathode is the negative terminal of an electrolytic cell, to which positively charged metallic ions travel. At the cathode, reduction takes place and hydrogen is evolved. In the reduction process, some of the positively charged metal ions in the compounds on the surface of the artifact are reduced to a metallic state in situ. In addition, chlorides and other anions are drawn from the specimen and migrate toward the positively charged anode by electrolytic attraction.
The tamu website contains lots of information about artifact preservation, but I find it overly complicated. A shorter description in laymans terms of the reasons for, and method to, build an electrlysis set-up is found at http://pub10.bravenet.com/forum/786256373/fetch/900041 There are multiple other sites that describe how to build the system that can be located using google.
Fire Diver, if I am wrong in this please let me know.
thanks all - did some soaking and some chipping and used some Black & Decker archaeological tools and here's what we end up with - the small end appears to be brass and fits onto the cylinder with threads - the main cylinder not sure but possibly iron steel or another metal - there are several pre-cut round holes in the cylinder - without coral weight is down to 10-15 lbs -