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Author Topic: Saving 400 Year Old Cannon Balls  (Read 477 times)

CarlS

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Saving 400 Year Old Cannon Balls
« on: March 14, 2018, 06:09:11 AM »
Perhaps this should be under "Miscellaneous" since it is more of a topic of conservation than cannon balls but there are some neat pics and discussion of cannon ball recovery:
   http://bit.ly/2FGI7Qk
What I don't understand is the apparent lack of use of electrolysis for conserving these.  I've never heard of any way around that and hopefully our resident archeologists can contribute some insight here.  Perhaps many hours of boiling would work but I'd be surprised if any chemical bath would penetrate as deep into the shell as 400 years of salt exposure has and remove or break down the salts.
Best,
Carl

speedenforcer

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Re: Saving 400 Year Old Cannon Balls
« Reply #1 on: March 14, 2018, 09:10:43 AM »
Really, I am surprised as you are Carl. They haven't heard of electrolysis?
It's not always "Survival of the fittest" sometimes the idiots get through.

Dave the plumber

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Re: Saving 400 Year Old Cannon Balls
« Reply #2 on: March 18, 2018, 06:48:17 PM »
I wonder too, if this is ignorance or 'thinking outside the box'.  With all their zillion dollar equipment, with  labs and students working on projects and such, maybe they can figure out something that has been overlooked  by everyone so far....

Ausmagic

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Re: Saving 400 Year Old Cannon Balls
« Reply #3 on: March 20, 2018, 10:58:16 PM »
Check out this article.  Cuts down the time for ridding salts from metal from years to days or weeks.

http://glimpse.clemson.edu/ridding-metal-of-salt/

CarlS

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Re: Saving 400 Year Old Cannon Balls
« Reply #4 on: March 21, 2018, 04:57:53 AM »
Wow, that is nothing short of spectacular to hear.  While it is not likely any time soon to get to an economic level where someone like I could have one for treating shells it could really allow a bunch of iron objects to see the light of day finally at museums, etc.  Thanks for sharing.

As a UGA grad I'm not sure I've ever said anything good about Clemsen but I will now: Good job Clemsen and Michael Drews!
Best,
Carl

misipirelichtr

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Re: Saving 400 Year Old Cannon Balls
« Reply #5 on: March 23, 2018, 10:15:41 AM »
Carl, I think Mike ought to get you one of those subcritical reactor thingamabobs to clean all those big hunks of iron he has sitting in drums of water around the world :-)

scottfromgeorgia

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Re: Saving 400 Year Old Cannon Balls
« Reply #6 on: March 23, 2018, 10:53:04 AM »
It's just a container under pressure. How expensive could it be? Any old boiler could do it.

CarlS

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Re: Saving 400 Year Old Cannon Balls
« Reply #7 on: March 23, 2018, 06:28:46 PM »
It is a container that must hold 800 PSI and also heat the fluid to 350 degrees.    It has to be built large enough to accept the object and able to open and close repeatedly without developing leaks.  What is still to be determined is how much fluid must surround the object and if there is some special mixture.  One would think if contacted they might share the secrets in order to facilitate the preservation of history but a lot of people tend to keep their knowledge close.

Also I wonder how much the thickness of the metal affects this process.  The breech of a large cannon has many inches of thickness where a shell is almost always less than 6 inches. Presumably it is just a few more days of run time.

I'd like to look into making one when I finish my current project.
Best,
Carl

speedenforcer

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Re: Saving 400 Year Old Cannon Balls
« Reply #8 on: March 23, 2018, 08:54:14 PM »
I'm with Scott on this one. I think it is very "Do"able for someone that has the time and extra funds. I don't think it would break the bank. Know the process, and you could make it work, it doesn't have to be fancy with all the bells, whistles, led lights strong enough to blind airplane pilots.
It's not always "Survival of the fittest" sometimes the idiots get through.

Dave the plumber

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Re: Saving 400 Year Old Cannon Balls
« Reply #9 on: March 23, 2018, 09:27:01 PM »
 before I'd start building an atomic reactor in my basement, I'd like to see the long term results of their work.   Don't forget these are the people that it seems did not know electrolysis existed for preserving relics.  I'd like to check back on their finished product in a few years and see if they are really driving the chlorides out completely, and they are getting proper stabilization of the relics.....   

speedenforcer

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Re: Saving 400 Year Old Cannon Balls
« Reply #10 on: March 24, 2018, 05:10:23 PM »
Makes sense Dave.
It's not always "Survival of the fittest" sometimes the idiots get through.

CarlS

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Re: Saving 400 Year Old Cannon Balls
« Reply #11 on: March 25, 2018, 11:36:38 AM »
David, I think you might have the two situations confused.  It was the first link posted by me with the English archeologists who have the cannon balls off the wreck that they don't know what to do with.  The 2nd link from Ausmagic is about an invention from Clemson University's archeology group and the Lasch Center (Michael Drews specifically) who seem to have the answer.  As the Lasch center started their work in 2003 they have a bit of history in their favor.  Ausmagic also found and sent me the patent info on the Lasch process which was filed in 2006:
      https://encrypted.google.com/patents/US8080110
so they felt good about the process even then.  So at this point it looks like a pretty decent process.  I'm  hoping to get some info from one of our forumites, Jim J, who you might remember from previous threads is the CSS Georgia archeologist and is involved with the Lasch Center.  Hopefully he is still reading the forum.
Best,
Carl

Ausmagic

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Re: Saving 400 Year Old Cannon Balls
« Reply #12 on: March 25, 2018, 12:01:16 PM »
I found an article in the Royal Society of Chemistry that described the processes they had been using to save the timbers, leather, iron cannonballs, and other artifacts recovered from the Mary Rose.  Here's an excerpt as relates to the cannonballs:

"So, for example, preventing corrosion in artefacts made from metals such as iron, bronze and copper, including guns, powder scoops, nails and bolts, requires removing chloride salts. The most effective technique for doing this, especially for iron artefacts, is hydrogen reduction, which involves heating the metal artefacts to a temperature of 850°C in a hydrogen atmosphere. Although effective, this technique is highly controversial because it changes the metallurgical structure of the artefact, whereas ideally the artefact should be preserved in its original condition.

‘This is the only method that has successfully removed total chlorides from iron found in the marine environment, but we’ve stopped using it,’ says Jones. Instead, they’ve switched to other techniques, such as alkaline sulfide methods, although these tend to be much slower, especially for large objects."

CarlS

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Re: Saving 400 Year Old Cannon Balls
« Reply #13 on: March 25, 2018, 02:52:11 PM »
Very interesting.  Heating something to 850°C (i.e. 1562°F) would certainly require specialized equipment and safety measure.  I suspect to get to that high temperature there is also high pressure involved. 

I certainly agree with "ideally the artefact should be preserved in its original condition".  Otherwise just make one of those resin copies and be done with it.

It would be neat to hear some comments from other archeologist, scientists and organizations on the Lasch process.
Best,
Carl