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<p>[QUOTE=&quot;Oldhoopster, post: 3030396, member: 84179&quot;]I am assuming that the area in question along the rim is RECESSED.&nbsp; If this is the case I would consider it a chipped die, but wouldn&#039;t get into an argument with someone who wanted to call it a cud.&nbsp; The bubbles under the bust bother me and I agree with [USER=1765]@messydesk[/USER] that it may be some sort of glue or polymer.&nbsp; It&#039;s just strange how it aligns with the rim chip.</p><p><br /></p><p>There is a failure mechanism in glass called glue chipping (it is also used as a decorative technique).&nbsp; When glue adheres to the surface of glass and begins to dry, it contracts.&nbsp; This puts localized areas of the glass into tension (glass and ceramics are pretty weak in tension) resulting in chips breaking off the surface.&nbsp; Metals aren&#039;t brittle so I don&#039;t know if this is applicable but if the bubbles indicate glue and the &quot;cracks&quot; seem to line up, maybe.&nbsp; I&#039;ve done fractography and break source analysis on glass and polycrystalline ceramics but not metals.&nbsp; I think [USER=33176]@Kentucky[/USER] or some others on here have metallurgy backgrounds and may be able to tell me I&#039;m wrong.</p><p><br /></p><p>BTW: is anybody old enough to remember windows falling out of the John Hancock Building in Boston during the 70&#039;s.&nbsp; Something similar was the root cause (consider that your useless engineering/science fact for the day<img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie8" alt=":D" unselectable="on" unselectable="on" />)[/QUOTE]</p><p><br /></p>

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