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Mystery Artifact Identified

June 2003
Monica Brook
Conservator

When iron artifacts are recovered from aqueous environments they are encrusted with a dense layer of coral concretion. This layer forms as a result of the cyclic action of organisms attaching themselves to the artifact then dying. Over time their skeletal remains build up eventually encapsulating the artifact in a dense, concrete-like cover. Although the artifacts are completely concealed within the concretion, they can usually be identified by their general shape and size. Identification is more difficult when two or more artifacts are encrusted together, or when an object is so unique there is nothing to compare it to, as was the case for our mystery artifact.

Despite being encrusted with nearly four hundred years worth of concretion, the general features of the mystery object were still visible. It had two thin parallel wrought iron bars connected by five intersecting bars. The middle bar was slightly longer than the others and the extended section was flat. It looked like a grate, and if it was, what was its purpose?

Fragments of the encrusted artifact before casting. The pieces were glued back together after the residue was removed to make the mold.

This oddity didn’t need to be stored wet like other encrusted objects because the metal had long since disintegrated leaving only a powdery residue inside the hollow concretion. It is unfortunate the artifact was destroyed by the natural forces of time, but fortunate that the artifact was encrusted, because the void inside the concretion, left behind by the 
disintegrated artifact, makes a perfect mold to cast a replica.

In order to cast hollow concretions the powdery residue from the corroded iron must be removed. Usually this is achieved by scribing small holes in the concretion and drilling out the residue with flexible wires. This method could not be used for the mystery object because it had too many sharp and narrow angles. Most likely these were the result of the powerful forces 
created when the ship sank. Surprisingly, the technique used to remove the residue was to break the concretion by cracking it open with a hammer. Typically conservation involves controlled, delicate actions, so it can be a bit unnerving hitting an encrusted artifact with a hammer, but this unorthodox technique works well. And you may have guessed, the tricky part is putting the broken pieces back together after the residue is removed.

After the mystery artifact was cast and its resin fully cured, it was time to remove the concretion and unveil the hidden object. No hammers this time, the concretion had to be removed very carefully with an air-scribe to avoid breaking the delicate cast. As the concretion was removed, intricate details started to emerge. Rivets and short tapered sections at the ends of the thin bars were now clearly visible. With the concretion removed and the replica clearly visible, speculations as to what this object was could end. Its identity was confirmed from an illustration in a book. There was no doubt the object was a trivet, a short-legged metal plate, or in this case a grate, that is placed under a cooking pot to protect a table or to support a 
vessel over a fire.

The replica artifact is held upside down to show the short tapered legs. The short flat piece on the middle bar, facing back, is the handle. Using the casting process, conservators are able to recreate an replica artifact from hollow concretions.

This is the first trivet in our collection from the 1622 Fleet. Although the original artifact may have disintegrated long ago, its hidden form was recreated through the casting process. Though not the original object, we now have a tangible replica and the mystery is solved.

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