Brushing off a little history

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The brush was removed from the starboard gun carriage, covered in mud and hard concretion.

Although my blogs to date give a very Dahlgren-centric view of what I do, there is far more to USS Monitor than just its guns. And I love having such a huge variety of objects to work on! In addition to big metal objects, we find a wide variety of organic objects, ranging from the wooden sides of the gun carriages to rope packing seals to a wool coat. We also have a number of brushes from on board the ship, including a nearly complete bench brush that I’ve been working on!

This brush was originally found stuck to one of the gun carriages, covered in mud and concretion – the hard, rocky material that forms around corroding iron. Although the brush itself is entirely organic – wood and fiber – it was so close to the iron of the gun carriage that it was caught inside concretion formed by that object. As a result, it didn’t look like much to begin with.   Read more

The Many Uses of X-rays

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MNMS-2002-01-757 BT1
The glass tube which could contain mercury.

Earlier this year we conducted a survey of all the small metal objects waiting to be conserved. We assessed the condition of each, took a photo, and changed solutions. We also slated some objects for x-radiography.

There are three reasons these particular objects were singled out. First is to determine the condition of the object. When artifacts are submerged in seawater they are covered in a cement-like aggregate called concretion. This is a mixture of metal corrosion products, sediment, and sea life, including mollusk and corals. Concretions can be a thin hard shell scattered across a surface or entirely encase a group of objects in an amorphous lump.  By x-raying these concretions we can:   Read more

From the Foundry: Carbon and X-rays

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Cast iron, like steel and wrought iron, is an alloy consisting primarily of iron and carbon but has a carbon content usually in the range of 2- 4%, which appears as flakes of graphite intermixed within the material. Commonly, when cast iron is submerged in a marine environment, the iron component corrodes away, leaving behind the graphite along with iron corrosion products. Iron in this state is often referred to as ‘graphitized’. Fortunately, even though the iron has corroded away, the shapes of cast iron objects recovered from marine sites often remain intact due to the surviving graphite holding the iron corrosion products in situ.  

To help illustrate the difference between non-corroded cast iron and graphitized cast iron, last week we x-rayed the damping piston valve cover next to one of its copies cast at the Buffalo State College Foundry.   Read more

USS Monitor’s Engine Room Clock – Part 1

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The USS Monitor’s engine room clock will be exhibited in a new display beginning March 5th 2010 at The Mariners’ Museum’s USS Monitor Center. Although the sturdy brass case and silvered face of Monitor’s engine room clock went on display with the opening of the USS Monitor Center in 2007, the mechanical heart of the clock, its movement, required more time in conservation treatment due to its complex nature and numerous small parts.    Read more