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<p>[QUOTE=&quot;calcol, post: 4958681, member: 77639&quot;]The ultrasonic scalers used by dentists usually have a metal tip, not something you would want to push across the surface of your coins.&nbsp;&nbsp; I believe that these devices in the U.S. are restricted to sales to licensed dentists, but no doubt you can find them on eBay and elsewhere.&nbsp; New, they are expensive and designed to work with a continuous stream of water.&nbsp; The water acts as a transmission medium, provides cooling and washes away loosened material.</p><p><br /></p><p>The use of ultrasound to clean coins has been discussed a number of times on this forum.&nbsp; Main worry is that they work by causing cavitation ... expanding and contracting gas/vacuum pockets in the fluid ... so cracking flawed or porous coins might happen.</p><p><br /></p><p>The scalers sold to consumers and advertised as “ultrasonic” aren’t.&nbsp;&nbsp; They vibrate at no more than 12,000x per second, which is sonic, not ultrasonic.&nbsp; Further, they use direct mechanical vibration of the tip, so even the “sonic” designation is arguable.&nbsp; Yeah, anything that vibrates in a gas or liquid will create sound waves, but the real work of consumer scalers is done mostly by the tip moving rapidly against the tooth surface.</p><p><br /></p><p>Cal[/QUOTE]</p><p><br /></p>

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