We are blogging as we dig into the archaeological records archived at Independence National Historical Park (INDE) in Philadelphia, Pennsylvania, USA. These records were created over the past 50 years as archaeologists researched sites within the park's boundaries. The Independence Park Archives is currently creating a Guide for this vast collection of documents. This blog serves toward that end. It functions as a platform where archaeologists, archivists, and the interested public can share ideas about how to make these materials more widely available and more useful to the user.
Read more about this project blog...

Friday, July 10, 2009

Ultrasonic Cleaning, 2009

A follow up to the recent discovery about ultrasonic cleaning of artifacts at INDE circa, 1960:

This photo, shot a few weeks ago, shows a park volunteer removing a basket of ceramic fragments from the ultrasonic cleaner at the Independence Living History Center Archeology Lab. Today an ultrasonic bath is often the first step in the artifact washing process. (Photo Credit: Jed Levin, 2009.)

Ultrasonic cleaning of archaeological remains is accomplished through 'inertial cavitation' - an explosion of tiny vapour bubbles that collapse and produce sound waves that remove particles. Modern ultrasonic cleaners are also equipped with a heater which improves the cleaning action.

A pH-balanced detergent is used to achieve cavitation. The ILHC Archeology Lab uses a mild horse shampoo called Orvis in its ultrasonic bath.

The ceramic, glass, and metal artifacts recovered from the archaeological sites at Independence Park are often processed in the ultrasonic cleaner. Depending on their composition and decoration, objects may stay in the bath anywhere from 20 minutes to an hour. Careful cleaning by hand is used for all items that are not suitable for ultrasonic cleaning.

A historical glance into the methods of American archeology - courtesy of the Independence Park Archives!