Marking

The Conservation Department at the Fortress of Louisbourg in Cape
Breton, Canada, was recently asked by our Collections/Archeological
department if we could find a product to replace fingernail polish
for the numbering of mass amounts of objects collected during
archeological digs, the majority of which are ceramic and glass
fragments.

The office space used to number each piece has poor ventilation and
while this isn't a problem when numbering just a few pieces, the
fumes accumulated from numbering 100's of pieces at a time using
fingernail polish can be a little too much. Unfortunately, we do not
have the funds necessary to improve ventilation.

During this search we came across a product from Golden Artist
Colors called Porcelain Restoration Glaze (PRG) available in gloss
or matte formulation. The label lists it as a reversible water-based
coating used to repair fine porcelain objects.

Initial tests showed that while it dried slower than fingernail
polish, the difference was very slight especially when mass
numbering. Both PRG gloss and fingernail polish had similar
appearances when dried. Both were easily soluble in acetone but not
ethanol. Further, long term immersion in water showed that PRG
dissolved while fingernail polish simply lifted off of the
substrate.  A comparison of costs show that both are available for
similar prices.

The MSDS sheets obtained from Golden Artist Colors reveal that the
only active ingredient is a small amount of ammonia which has a
vapour density heavier than air. During its testing no fumes were
noticed even after numbering 50 to 100 objects at a time.

Although originally the alternative was needed solely for numbering
ceramic and glass pieces preliminary tests show that the PRG causes
no harm to copper, iron, and lead which are the  metals most
commonly found here at the Fortress of Louisbourg.

For ease of use the PRG was placed into cleaned fingernail polish
bottles and was applied with a brush. Numbering was found to work
best using acrylic inks. We noticed that other inks did not appear
to adhere as well to PRG and would sometimes start to lift as a top
coat was brushed on if they did not have enough time to fully set.

While these tests are just the first step, this product shows
considerable promise as an alternative to the more tradition
fingernail polish in numbering museum and historic site collections.

Ian Loughead
Conservator, Fortress of Louisbourg


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                  Conservation DistList Instance 14:16
                 Distributed: Sunday, September 3, 2000
                       Message Id: cdl-14-16-001
                                  ***