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<p>[QUOTE=&quot;-jeffB, post: 2716917, member: 27832&quot;]Tarn-X would take them away if you <i>scrubbed</i> enough, because it&#039;s got clay (and acids, buffers, and surfactants), according to its MSDS.</p><p><br /></p><p>What it apparently <i>doesn&#039;t</i> have is a nonpolar solvent to take away the organic-gunk ink a Sharpie leaves behind.</p><p><br /></p><p>Here&#039;s a story of a similar process:</p><p><br /></p><p>In the old days when I first got into electronics, it was common to hand-make your own printed circuit boards -- a board with copper lines on it to serve as connections. You&#039;d start with a plastic board with a copper layer on one side. You would draw the pattern for your circuit onto the copper layer with a &quot;resist pen&quot;, essentially a very goopy Sharpie. Once that dried, you&#039;d dip the board into a strong solution of ferric chloride (aka Nic-A-Date). That ferric chloride would <i>dissolve</i> the copper, <i>without affecting</i> the resist pen marks, nor the copper under them. When it was done, you&#039;d rinse the board thoroughly, dry it, and then remove the resist. I think I used rubbing alcohol (acetone would have attacked the board), but it was also acceptable to just sand off the resist.</p><p><br /></p><p>If you didn&#039;t draw heavily enough with the resist pen, the etchant would attack the copper underneath it, but it still wouldn&#039;t affect the resist itself. (If you left it in long enough to etch away the copper underneath completely, the resist would float off, because there was nothing left for it to be attached to.) The resist is essentially plastic bits and pigment; it doesn&#039;t care about acids.</p><p><br /></p><p>The behavior you&#039;ve described on that Lincoln seems consistent with what I&#039;ve seen on circuit boards.[/QUOTE]</p><p><br /></p>

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