Oddy test

I am carrying out Oddy tests on gap-filling materials for enamels on
metal. I have found some references in the literature describing the
directions for setting up the test, but of those, just one gives
information on how to evaluate and interpret the results--color
shift, surface condition, localization and morphology and changes:

    Green (L.R.), Thickett (D.)
    "Testing Materials for Use in the Storage and Display of
    Antiquities. A Revised Methodology"
    Studies in Conservation, vol. 40, n0 3, 1995, p. 145-152.

I do have other questions about interpretation of results such as
the following, and I am looking for advice or further references.

    *   How to distinguish corrosion of the coupon produced by high
        HR from corrosion due to the tested product?

    *   I observe condensation on the surface of the metal coupons
        during testing. Is this acceptable?

    *   Does the aspect of corrosion permits to identify the
        corrosion product type (i. e. corrosion of lead shows
        sometimes three or four different colors)?

    *   How to interpret the case where you have corrosion of the
        metal around the tested product (in contact) but not under
        it. Does that mean that the product protects the metal?

    *   Does other criteria such as odor in the vessels or extension
        and surface relief of the corrosion have been studied and
        validated?

I would be thankful for any answer that would enable me to improve
interpretation clues.

Agnes Gall-Ortlik
Ceramic and Glass Conservator


                                  ***
                  Conservation DistList Instance 14:46
               Distributed: Wednesday, February 21, 2001
                       Message Id: cdl-14-46-014
                                  ***