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
Maryland History by the Object 