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<p>[QUOTE=&quot;Insider, post: 7637252, member: 24314&quot;]<span style="color: rgb(102, 0, 0)"><b>porosity</b></span></p><p><span style="color: rgb(102, 0, 0)">(1) <b><i><font size="6">Fine holes or <font size="6">pores</font> within a solid</font></i></b></span>; the amount of these pores is expressed as a percentage of the total volume of the solid. (2) Cavity-type discontinuities in weldments formed by gas entrapment during solidification. (3) A characteristic of being porous, with voids or pores resulting from trapped air or shrinkage in a casting. See also gas porosity and pinhole porosity.</p><p><br /></p><p><b>gas porosity</b></p><p>Fine holes or pores within a metal that are caused by entrapped gas or by the evolution of dissolved gas during solidification.</p><p><br /></p><p><b>pinhole porosity</b></p><p>Porosity consisting of numerous small gas holes (pinholes) distributed throughout the metal; found in weld metal, castings, and electrodeposited metal.</p><p><br /></p><p>It is my understanding that educated numismatists (principally the early copper collectors a VERY LONG TIME AGO before either of us were born) have adopted this metallurgical term to describe the pitted surface found on coins due to corrosion (actual environmental damage <img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie8" alt=":D" unselectable="on" unselectable="on" />).</p><p><br /></p><p>THIS POST HAS BEEN EDITED JUST NOW TO MAKE IT MUCH EASIER TO UNDERSTAND.<img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie8" alt=":D" unselectable="on" unselectable="on" /><img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie7" alt=":p" unselectable="on" unselectable="on" />[/QUOTE]</p><p><br /></p>

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