Do Not Migrate


The National Center for Preservation Technology and Training (NCPTT) and the American Institute for Conservation of Artistic and Historic Works (AIC) are hosting a half day workshop on the use of Eddy Currents in conservation on Tuesday, May 19, 2009 in Los Angeles, California. The workshop precedes the annual meeting of the AIC. Go to for more information.

Eddy Current Metal Testing for Conservation
1:00 – 4:00 p.m.; $79
Curtis Desselles (Northwestern State University), Jason W. Church, and Mary F. Striegel, (NCPTT).

Organized and presented by the National Center for Preservation Technology and Training
This workshop will demonstrate the use of eddy currents for identification of metals (ferrous and non-ferrous), measurement of the thickness of corrosion, and recovery of serial numbers and/or images beneath corrosion. Attendees will learn the theory of eddy current analysis and will assemble a low-cost, working portable eddy current tester. Attendees will learn the skills necessary for using eddy current analysis in the field of heritage preservation. Participants are encouraged to bring samples for testing.


Curtis Desselles, lead instructor. Curtis Desselles is retired from the U.S. Navy where he specialized in laboratory medicine. While in the Navy, Mr. Desselles acquired a B.S. in Physics, and became a Microsoft Software Engineer. Upon retirement, Mr. Desselles acquired a B.A. in Anthropology and is currenly is master’s candidate in Heritage Resources.  He is undertaking a practicum at the National Center for Preservation Technology and Training, where he is developing applications for portable eddy current metal testers.

Jason Church, assistant lab instructor. Jason Church holds a M.S. in historic preservation from the Savannah College of Art and Design.  He has been the Materials Conservator at NCPTT for four years.  He specializes in the preservation of historic cemeteries including grave markers and ornamental fencing.

Mary F. Striegel, workshop coordinator. Mary Striegel is the chief of materials research at NCPTT, where she oversees research and leads in training development for new preservation technologies.  She holds a Ph.D. in inorganic chemistry from Washington University, St. Louis.  She has 20 years experience in research pertaining to conservation of artwork and preservation of heritage resources.

Workshop Outline

Eddy Current Metal Testing in Conservation Workshop

Introduction to eddy currents

  1. Define eddy currents
    1. Eddy currents are analogous to a stream. When the bed of the stream is smooth, the water flows in a continuous current. If the stream bottom has rocks protruding from the surface, circular currents (eddies) will surround the rocks. A wire or coil carrying an alternating current (AC) will induce a current in a metal object when in close proximity. This induced current can be measured and graphically represented to show defects in metals, identify metals, measure the thickness of corrosion, and recover marks or images located under the corrosion.
  2. Background and scientific theory
    1. Eddy current analysis has been around for over 50 years, but new technological advances can create additional uses for the eddy current analysis.
    2. Michael Faraday’s Law and the work of Joseph Henry
  3. Applications of eddy currents to heritage resources
    1. Non-destructive metal identification
    2. Non-destructive measurement of corrosion thickness
    3. Non-destructive recovery of marks or images beneath corrosion layers
    4. Non-destructive analysis of gilded samples
    5. Portability of eddy current metal tester for use in the field
    6. Cost effectiveness of creating a commercial-grade eddy current tester for under $100.00
  4. Demonstration of instrument construction
    1. Building an eddy current probe
    2. Discussion of the electronics and parts needed
    3. Discussion of the software for analysis
  5. Lab Session
    1. Hands-on testing of samples and interpretation of results
    2. Attendees may bring test samples

National Center for Preservation Technology and Training
645 University Parkway
Natchitoches, LA 71457

Email: ncptt[at]
Phone: (318) 356-7444
Fax: (318) 356-9119