{"id":14688,"date":"2016-06-02T11:09:00","date_gmt":"2016-06-02T16:09:00","guid":{"rendered":"http:\/\/www.conservators-converse.org\/?p=14688"},"modified":"2016-06-02T11:09:00","modified_gmt":"2016-06-02T16:09:00","slug":"44th-annual-meeting-may-14th-ferrous-attractions-the-science-behind-the-magic-by-gwen-spicer","status":"publish","type":"post","link":"https:\/\/resources.culturalheritage.org\/conservators-converse\/2016\/06\/02\/44th-annual-meeting-may-14th-ferrous-attractions-the-science-behind-the-magic-by-gwen-spicer\/","title":{"rendered":"44th Annual Meeting, May 14th, &quot;Ferrous Attractions: The Science Behind the Magic&quot; by Gwen Spicer"},"content":{"rendered":"<p>The workshop <em>Ferrous Attractions: The Science Behind the Magic<\/em>\u00a0was led by Gwen Spicer (Spicer Art Conservation, LLC) and Van Wood (Small Corp Inc.). \u00a0The program was outlined\u00a0in three sections: introduction to the magnetic system, hands-on testing, and a brief summary of testing results.<br \/>\nThe <strong>magnetic system<\/strong> includes four\u00a0components:<\/p>\n<ul>\n<li>the strength of the magnet,<\/li>\n<li>the type of ferromagnetic material receiving the magnet,<\/li>\n<li>the space between them (occupied by the artwork),<\/li>\n<li>and gap materials (those in contact with the artwork: fabric, Mylar, twill, batting, paper, or suede).<\/li>\n<\/ul>\n<p>Magnetic systems can be assembled in\u00a0several different ways:<\/p>\n<ul>\n<li>Two-part (point fastener): magnet\/magnet or magnet\/ferromagnetic material.<\/li>\n<li>Three-part (sandwich): ferromagnetic material\/magnet\/ferromagnetic material or magnet\/magnet\/ferromagnetic material.<\/li>\n<li>Large area pressure: flexible magnet\/ferromagnetic material or magnetic slat\/ferromagnetic material.<\/li>\n<\/ul>\n<p>The ferromagnetic material, commonly 24 gauge steel, is called a\u00a0&#8220;soft magnet&#8221; because it is magnetized in\u00a0the presence of a permanent magnet.<br \/>\nConservators typically use neodymium permanent magnets.\u00a0Neodymium magnets are considered the strongest, yet their sourcing is ethically problematic &#8211;\u00a0details of\u00a0their mining and trade were\u00a0addressed in Gwen&#8217;s 2015 AIC <a href=\"http:\/\/www.conservators-converse.org\/2016\/05\/43rd-annual-meeting-may-15-2015-the-how-and-why-of-reusing-earth-magnets-with-gwen-spicer\/\">Sustainability<\/a> session talk. \u00a0This <a href=\"http:\/\/spicerart.com\/wp-content\/uploads\/2015\/05\/Comparison-Table-of-Magnets.pdf\">table<\/a>\u00a0compares other types of magnets you may encounter.<br \/>\n<strong>Hands on testing<\/strong> was done in pairs using a wooden jig, bucket,\u00a0weights, and a kit of various magnets, metals, and gap materials. The\u00a0test:\u00a0choose a type of magnetic system, suspend the bucket, and fill it until the system\u00a0fails (ie. the bucket drops). \u00a0Images of the jig and testing results from a previous workshop are found on Gwen&#8217;s <a href=\"http:\/\/insidetheconservatorsstudio.blogspot.com\/2013\/05\/ferrous-attraction-and-science-behind.html\">blog<\/a>.<\/p>\n<p style=\"text-align: left\">Many factors influence the strength of a\u00a0permanent magnet including:<\/p>\n<ul>\n<li>shape (disc\/cylinder, sphere, block, ring)<\/li>\n<li>size (diameter, thickness)<\/li>\n<li>grade (&#8220;strength&#8221; of the magnet &#8211; the higher the N# the stronger &#8211;\u00a0N42 and N52 are common)<\/li>\n<li>pull force (force required to\u00a0separate\u00a0the\u00a0magnet from steel or another magnet)<\/li>\n<li>pole orientation (axial or diametrically magnetized)<\/li>\n<li>Curie temperature (temperature\u00a0at which the magnet is demagnetized)<\/li>\n<li>intrinsic coercive force (resistance\u00a0to demagnetization).<\/li>\n<\/ul>\n<p>K &amp; J Magnetics Inc. discusses these aspects\u00a0in detail in\u00a0their <a href=\"https:\/\/www.kjmagnetics.com\/blog.asp?p=magnet-grade\">blog<\/a>\u00a0and <a href=\"https:\/\/www.kjmagnetics.com\/glossary.asp\">glossary<\/a>. They also offer a Magnetic Pull Force <a href=\"https:\/\/www.kjmagnetics.com\/calculator.asp\">Calculator <\/a>to\u00a0aid in selecting magnets for appropriate use!<br \/>\n<strong>Tips from the summary\u00a0discussion:<\/strong><\/p>\n<ul>\n<li>Do not use hot glue or irons near magnets because the heat can demagnetize them. For example, the Curie temperature for neodymium magnets is considered low: 310-400 degrees Celsius.<\/li>\n<li>Do not put cell phone near strong\u00a0magnets!<\/li>\n<\/ul>\n<p>Magnets &#8211;<\/p>\n<ul>\n<li>Axial magnetic attraction is stronger\u00a0than diametric (side to side) attraction. Always check the pole orientation when purchasing.<\/li>\n<li>Match your magnets! Magnets of similar diameter and pull force will behave the most regularly. Magnets that differ by more than\u00a01\/8&#8243; diameter\u00a0will slip\u00a0because the magnetic field is not evenly distributed.<\/li>\n<li>Neodymium magnets corrode easily and therefore require a coating. They are brittle and chip easily. They are hard to demagnetize, but they can easily\u00a0demagnetize other magnets!<\/li>\n<li>Three-part systems are the strongest.\u00a0Magnets can be bundled to increase pull force.\n<ul>\n<li>Is the pull force additive or logarithmic?<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>Ferromagnetic materials &#8211;<\/p>\n<ul>\n<li>Steel powders were deemed ineffective by the group overall\u00a0&#8211;\u00a0you need A LOT of it.<\/li>\n<li>24 gauge steel is the sweet spot &#8211; higher gauge steel is only minimally stronger.<\/li>\n<li>Using a thinner magnet on the artifact surface and a thicker one behind reduces the total pull force of the two magnets.<\/li>\n<li>Beware of\u00a0steel washers. The hole significantly reduces the pull force and causes\u00a0the magnet to slip.<\/li>\n<\/ul>\n<p>Gap materials &#8211;<\/p>\n<ul>\n<li>The best gap material is decidedly Benchmark suede (to cover the magnets)\u00a0due to the suede&#8217;s friction and slight give &#8211; better than\u00a0Mylar or cotton. Polyester batting was the worst because the gap is too big.\n<ul>\n<li>What is the optimal or minimal gap for your magnetic system?<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>Gwen Spicer is writing a book on magnets in conservation, supported by the\u00a0AIC Kress publication\u00a0fellowship. If you have a Case Study you would like to share, please <a href=\"http:\/\/spicerart.com\/wp-content\/uploads\/2014\/11\/Case-Study-Submission.pdf\">get in touch<\/a>!<br \/>\n&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The workshop Ferrous Attractions: The Science Behind the Magic\u00a0was led by Gwen Spicer (Spicer Art Conservation, LLC) and Van Wood (Small Corp Inc.). \u00a0The program was outlined\u00a0in three sections: introduction to the magnetic system, hands-on testing, and a brief summary of testing results. The magnetic system includes four\u00a0components: the strength of the magnet, the type &hellip; <a href=\"https:\/\/resources.culturalheritage.org\/conservators-converse\/2016\/06\/02\/44th-annual-meeting-may-14th-ferrous-attractions-the-science-behind-the-magic-by-gwen-spicer\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;44th Annual Meeting, May 14th, &quot;Ferrous Attractions: The Science Behind the Magic&quot; by Gwen Spicer&#8221;<\/span><\/a><\/p>\n","protected":false},"author":217,"featured_media":14007,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,20],"tags":[76],"class_list":["post-14688","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-annual-meeting","category-reception","tag-aics-44th-annual-meeting"],"_links":{"self":[{"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/posts\/14688","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\/217"}],"replies":[{"embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/comments?post=14688"}],"version-history":[{"count":0,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/posts\/14688\/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=14688"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/categories?post=14688"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/resources.culturalheritage.org\/conservators-converse\/wp-json\/wp\/v2\/tags?post=14688"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}