{"id":10938,"date":"2014-06-29T11:36:45","date_gmt":"2014-06-29T16:36:45","guid":{"rendered":"http:\/\/www.conservators-converse.org\/?p=10938"},"modified":"2014-06-29T11:36:45","modified_gmt":"2014-06-29T16:36:45","slug":"42nd-annual-meeting-general-session-may-30-blue-red-and-wound-all-over-evaluating-condition-changes-and-cleaning-of-glass-disease-on-beads-by-robin-ohern-and-kelly-mch","status":"publish","type":"post","link":"https:\/\/resources.culturalheritage.org\/conservators-converse\/2014\/06\/29\/42nd-annual-meeting-general-session-may-30-blue-red-and-wound-all-over-evaluating-condition-changes-and-cleaning-of-glass-disease-on-beads-by-robin-ohern-and-kelly-mch\/","title":{"rendered":"42nd Annual Meeting- OSG + RATS Session, May 30, \u201cBlue, Red, and Wound All Over: Evaluating Condition Changes and Cleaning of Glass Disease on Beads\u201d by Robin O\u2019Hern and Kelly McHugh"},"content":{"rendered":"<p>Glass disease, weeping glass, glass deterioration, funky glass* (*author\u2019s description)&#8211;just a few of the many names used to describe the degradation of glass beads that museums have observed as a white precipitate\/cloudy appearance and\/or cracking and splitting. \u00a0If you&#8217;ve observed this in your collection, take notice- Mellon Fellow in Objects Conservation, Robin O\u2019Hern, is on the case.<br \/>\nO\u2019Hern has taken advantage of the history of glass disease detection at the National Museum of the American Indian (<a href=\"http:\/\/nmai.si.edu\/home\/\">NMAI<\/a>) and begun evaluating how the different cleaning methods have fared over the years. \u00a0In 1999, Kelly McHugh (research supervisor and co-author) and Scott Carrlee performed a condition survey of the NMAI collection. \u00a0The collection was moved into a state-of-the-art storage facility after the survey, where the RH has remained constant, but at a higher level than recommended for glass pieces. \u00a0(The beads are present on composite pieces with hide, bone, shell, feather, hair, etc. and therefore the environmental controls must address as many materials as possible, not just glass.) \u00a0Some of the pieces were treated at that time, and others have been treated in the interim years. \u00a0Using the museum database, O&#8217;Hern found that 25% of the condition records that list glass beads as a material also list glass disease. \u00a0O\u2019Hern has performed another survey, this time seeking to observe condition changes over the past 15 years in a selection of objects from the 1999 survey, to assess treatment technique (ie, which solvents worked best to reduce glass disease), and to discover susceptibility trends (which beads are the worst culprits).<br \/>\nTo understand the beads, O\u2019Hern provided background on history of use and manufacture.<\/p>\n<ul>\n<li>Glass beads arrived after contact with Europeans in 1492<\/li>\n<li>Pony beads were introduced after 1675<\/li>\n<li>Wound beads were introduced after the late 17th century<\/li>\n<li>Seed beads were introduced 1710-1840<\/li>\n<li>Red beads were colored from copper in the 17th century, ruby red in the early 18th century, and selenium in the 1890\u2019s<\/li>\n<li>Blue beads were colored from copper or cobalt, but from 1640-1700, they were tin-rich<\/li>\n<li>Beads can be made by pulling the heated glass, called \u201cdrawn,\u201d or by winding heated glass around a rod, called \u201cwound\u201d<\/li>\n<li>Glass is made from silica, alkali (to lower the melting point, but also makes it water soluble), and calcium carbonate (that turns to lime- it\u2019s added to help stabilize the glass after the alkali)<\/li>\n<\/ul>\n<p>There are several explanations for the cause of glass disease. \u00a0Too little or too much of the lime (part of the bead\u2019s composition) may cause water to leach out of the glass matrix as ions that then form salt on the surface of the bead. \u00a0The environmental conditions, such as fluctuations in RH, or materials in proximity, such as semi-tanned hide, may accelerate glass disease. \u00a0As seen from the list above, the beads were manufactured over a range of time, in different ways, and in different places.<br \/>\nAs you can tell, there are many factors to research when evaluating glass disease. \u00a0O\u2019Hern addressed as many as possible while still managing the scope of the project.<br \/>\n<span style=\"text-decoration: underline\">Survey Results<\/span><br \/>\nCondition Change: By comparing condition of the beads today to past condition\/treatment reports, 16% of the beads have more deterioration now than in 1999. \u00a0Measuring pH was used in addition to visual examination to determine condition. \u00a0Some beads that did not look bad had a higher pH (above 7), signaling glass disease. \u00a0Some beads that looked hazy did not have a higher pH, meaning no glass disease (perhaps hazy from manufacture).<br \/>\nDiffering Manufacturing Techniques: \u00a0Wound beads have it worse than drawn beads&#8211;95% of wound beads have glass disease. \u00a0This could be because they have a compositional percentage of lime that is less stable.<br \/>\nDiffering Colors: Black, red, and blue are the most disease-ridden. \u00a0O\u2019Hern looked through the museum database and found that the entries with the most \u201cglass disease\u201d indicated had blue beads. \u00a0Blue beads are very clearly the \u201cwinner\u201d of the glass disease competition, followed by red and black.<br \/>\nTreatment Techniques: \u00a0Here\u2019s where it gets even more interesting. \u00a0The conservation literature and posts on the Objects Specialty Group list serve debate the use of three solvents to remove the salts on glass disease: water alone, ethanol alone, and a 1:1 water:ethanol mix. \u00a0By comparing the 1999 survey to her own results, O\u2019Hern capitalized on real-time aging to observe how each solvent mixture fares over time. \u00a0Water-cleaned beads had a 50% rate of glass disease return; water:ethanol-cleaned had a slightly higher than 50% rate of return; ethanol-cleaned had the least amount of return at just under 50%. \u00a0However, <span style=\"color: #222222\">when looking at the beads cleaned with ethanol over the same time period as those cleaned with 1:1 water:ethanol (removing the very oldest treatments), the rate of return for glass disease falls to 40%.<\/span><br \/>\n(Note: Acetone has also been listed as a solvent for cleaning glass beads, but since the NMAI doesn&#8217;t use acetone, it was not included in this research.)<br \/>\n<span style=\"text-decoration: underline\">Other Observations:<\/span><br \/>\n1. Measuring pH is essential because beads may look like they don\u2019t have glass disease, but are actually more alkaline. \u00a0Measuring pH is also quick and easy- cut your pH strip to a small piece, slightly dampen it in deionized water, press it onto the bead for 3 seconds, and then determine any color change in the strip.<br \/>\n2. The most affected beads were those sewn onto hide, but the disease was present when beads were in contact with many other materials as well.<br \/>\n3. Although cleaning with ethanol is a better choice for long-term disease prevention, the solvent chosen should still depend on the substrate around the bead.<br \/>\n<span style=\"text-decoration: underline\">Advice from O\u2019Hern:<\/span><br \/>\n1. Record treatment materials when removing glass disease.<br \/>\n2. Take BT and AT details of beads so you can easily compare for condition changes in the future.<br \/>\n3. Measure the pH of the beads&#8230; and RECORD THE RESULTS.<br \/>\n4. Have consistent monitoring of glass disease.<br \/>\nAs an audience member, it\u2019s always exciting to see a project that has results, especially on a topic that is not studied as extensively as it persists. This is definitely a postprint worth visiting for more details and results.<br \/>\nFor other examples (and some \u201cgood\u201d photographic examples), visit Ellen Carrlee\u2019s project \u201cWhat\u2019s that White Stuff?\u201d that she and (then WUDPAC graduate intern) Christa Pack reported on in Ellen\u2019s blog: <a href=\"http:\/\/alaskawhitestuffid.wordpress.com\/2011\/08\/09\/glass\/\">http:\/\/alaskawhitestuffid.wordpress.com\/2011\/08\/09\/glass\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Glass disease, weeping glass, glass deterioration, funky glass* (*author\u2019s description)&#8211;just a few of the many names used to describe the degradation of glass beads that museums have observed as a white precipitate\/cloudy appearance and\/or cracking and splitting. \u00a0If you&#8217;ve observed this in your collection, take notice- Mellon Fellow in Objects Conservation, Robin O\u2019Hern, is on &hellip; <a href=\"https:\/\/resources.culturalheritage.org\/conservators-converse\/2014\/06\/29\/42nd-annual-meeting-general-session-may-30-blue-red-and-wound-all-over-evaluating-condition-changes-and-cleaning-of-glass-disease-on-beads-by-robin-ohern-and-kelly-mch\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;42nd Annual Meeting- OSG + RATS Session, May 30, \u201cBlue, Red, and Wound All Over: Evaluating Condition Changes and Cleaning of Glass Disease on Beads\u201d by Robin O\u2019Hern and Kelly McHugh&#8221;<\/span><\/a><\/p>\n","protected":false},"author":183,"featured_media":10236,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,32,38,16],"tags":[73],"class_list":["post-10938","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-annual-meeting","category-objects","category-research-materials-techniques","category-specialty-sessions","tag-aics-42nd-annual-meeting"],"_links":{"self":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/posts\/10938","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/users\/183"}],"replies":[{"embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/comments?post=10938"}],"version-history":[{"count":0,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/posts\/10938\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/"}],"wp:attachment":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/media?parent=10938"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/categories?post=10938"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/tags?post=10938"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}