Mystery object: part II

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Cross-section of the concretion showing stacked straps of leather.

Thanks to Riverside Regional Medical Center, our “mystery object” received a CT scan a few weeks ago!
We are so grateful for the help our health care neighbors provided with the project.
Also, thank you all for the many suggestions last month on what could be trapped within this concretion!
So… what did we find?!
A whole lot of precious information for conservation purposes!
First of all, the CT scan confirmed that any metallic material left within the concretion is fully mineralized, in other words, there is no more metal left, only metallic corrosion products.
Second, we now know that there is a LOT of leather left inside this concretion. The object is composed of many leather straps, sometimes up to 7 of them stacked on top of one another. See these pictures of cross sections of the concretion:

In the following picture, an o-ring can be seen from which at least two small straps depart (yellow arrow). On one of these straps, stiches can be seen (red arrows).
   Read more

Last week’s team effort on USS Monitor’s main engine

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The whole conservation team was busy doing some maintenance work on the USS Monitor main steam engine last week. It involved the following:
• draining the 20,000 gallons of solution, removing the stainless steel anodes and the reference electrodes
• performing a detailed conservation assessment of the engine
• thorough photo documentation of the current state of the artifact, and using these pictures to produce a 3D model of the engine
• cleaning the anodes and prepping new reference electrodes
• putting everything back in place and covering it all with a fresh caustic solution
We also were able to bring Museum staff members for a close-up view of this large object while the tank was drained. The perks of the job!
Below are a few pictures of the process for those of you who did not have a chance to check out our webcams or to come see us work live!

Now power is back on in the tank. The reference electrodes judiciously located around the engine will allow us to monitor the electrolytic reduction process in live time and to adjust the current if need be.

There is a Civil War Lecture this Saturday at 2pm: “Conserving Civil War Shipwreck: Research and Innovation”. It is free with museum admission. Come hear more about what we do behind the scenes!    Read more

Mystery Object

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Mystery object’s x-ray

Hi all,

Among other endeavors, a mystery object was found within our collection. It is a lengthy, semi-oblong shaped concretion, excavated in 2001 in proximity to the engine room of the Monitor. It has been stored dried for a while, and a recent look at it showed that at least four straps of leather were intertwined within the hard mixture of corrosion products and calcite. In addition to the leather, a couple copper alloy ornate buttons were also identified. A few X-rays were performed in-house last week to attempt a better identification of the object. Unfortunately the thickness of the concretion did not allow for a very clear image. See for yourself:   Read more

The port Dahlgren gun carriage is fully disassembled!         

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Details of the bottom plates, friction plates and friction rollers. View from below and transverse section. Peterkin, 1985.

Last week Will was able to escape his desk for a few days and help take apart the last elements of the port gun carriage.

The complete braking mechanism was still in place, but by separating all of the parts  we are able to maximize the amount of salts extracted from the artifact down the road (aka: a conservator’s dream!). After studying the historic blue prints (see historic plan below), we knew that one piece was the key to this puzzle. We also knew that we would need access to both the upper- and under-side of the carriage. In order to gain access to both, Will custom welded a rig allowing the artifact to stand vertically during treatment.   Read more