Conservation of Smith’s St. Leonard Artifacts

Various metal objects from the cellar feature of the Smith’s St. Leonard site are being treated in the conservation department of the MAC Lab. Among them are buttons, thimbles, spoons, buckles, hinge parts, and a piece of a furniture escutcheon (a plate or flange that protects the wood of the furniture from being struck by the handle). There are also a couple of unknown objects, the cleaning and conservation of which may help archaeologists identify them. In addition to the metal objects being treated, conservators have also begun working on the portion of a foldable fan discovered in the cellar. The ivory fan “sticks” (the part of the fan that would be held in your hand) will be cleaned, and the copper alloy “rivet” (the piece that fastens the sticks together) will be treated to stabilize the metal.

One of the unidentified metal artifacts

Archaeologist delicately removing remains of the fan from the cellar feature

Treating the Screw-piles

Conservator Cait Shaffer has begun cleaning the much concreted surfaces of the two screw-piles from the Drum Point Lighthouse that recently arrived at the MAC Lab. She initially tried cleaning the artifacts with air abrasion and a Dremel rotary tool, but many of the concretions on the objects are too hard for these methods to remove them. Cait is now using an air scribe, which is like a tiny jack hammer, and it has been working well. And for the thickest of the concretions, she is dexterously using a chisel and hammer for their removal. After the cleaning process is completed, a protective coating will be applied to the screw-piles.

Using the air scribe to remove concretions

Heavily concreted screw-pile

Close up of concretion

What is That?

It started as an unidentifiable mass and ended up being a rather rewarding conservation project. A heavily concreted lump of metal was found at an 18th-19th century site located on the Aberdeen Proving Ground, a United States Army facility located near Aberdeen, Maryland, in Harford County. The object was taken to the MAC Lab (along with the other artifacts from the site) and x-rayed as the first step in the conservation treatment process. The x-ray showed that the metal lump was an iron chain solidly encased in corrosion material. Conservator Cait Shaffer undertook the labor of freeing the chain. After 40 treatment hours, each link of the chain was separated from the concretion and the artifact was fully conserved. According to Cait, freeing the chain links was time consuming but quite satisfying.

The concreted iron chain before treatment.

X-ray of chain.

Chain during conservation treatment.


Courtesy U.S. Army Garrison, Aberdeen Proving Ground