MCI Project Summaries 2008 - Smithsonian Institution
MCI Project Summaries 2008 - Smithsonian Institution
MCI Project Summaries 2008 - Smithsonian Institution
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<strong>MCI</strong> 6234 Residue on Exhibit Case Windows<br />
<strong>MCI</strong> Staff: Jennifer Giaccai, Nicole C. Little<br />
White efflorescence was observed forming on the inside of the glass window in sealed<br />
drawers in the NMAI exhibition Windows on the Collection. Two different manifestations were<br />
observed; some samples were obviously crystalline while others appeared more as a slight<br />
fogginess or cloudiness on the glass. More drawers were affected than were sampled. Drawers<br />
labeled AN did not show any cloudiness in the front one inch of the drawer. The raking light<br />
used in the exhibition drawers highlights the formation of the crystals, so that the crystals are<br />
extremely distracting to the observer although there is only a small amount of sample present.<br />
Although there was variation in the samples collected, the overwhelming composition of<br />
most of the samples was sodium formate. This salt was most likely formed when formic acid or<br />
formaldehyde was released from one of the components making up the case or from improperly<br />
sealed wood. The formic acid reacted with sodium present as a component of the glass, and<br />
formed sodium formate crystals on the inside glass of the sealed exhibit drawers.<br />
<strong>MCI</strong> 6241.1 Anchorage Loan: Tlingit Stikine Copper Rattle<br />
<strong>MCI</strong> Staff: Nicole C. Little, Ron H. Cunningham, Harriet (Rae) F. Beaubien<br />
This Tlingit rattle is included in the SI loan (NMNH and NMAI) to the Anchorage<br />
Museum of History and Art, and will be on display for 12 years. It is suspected that several<br />
corroded areas on the mask may have "bronze disease", which is caused by chloride<br />
contamination and is indicated by the following products: atacamite<br />
Cu2CI(OH)3, paratacamite Cu2Cl(OH)3, or nantokite CuCI. Past photographs indicate that this<br />
has been present for an extended period of time and has not worsened. This is of greater concern<br />
now, as the object will be travelling to Alaska and will be installed in a new facility with a new<br />
HVAC system , which might expose it to unstable environmental conditions, thus exacerbating<br />
the problem. The characterization of the corrosion product through XRD analysis can determine<br />
if bronze disease is present. The results of this analysis will inform our treatment decision. X-ray<br />
analysis will elucidate construction methodology.<br />
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