Sonics VC500 - Manual (Page 21)

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To inhibit sample loss in test tube due to sticking, siliconize the test tube as follows:
Wash and dry the test tube thoroughly, coat with silicone, then air dry. “Sigmacote”
manufactured by Sigma Chemical Co., 3050 Spruce Street, St. Louis, Missouri 63103,
USA, phone (314) 771-5765, is ideally suited for that purpose.
High viscosity and concentration are problematic. 2,000 cps and 15% concentration by
weight are maximum limits. Because with ultrasonics the sound waves are propagated
through the sample, if the sample is so thick that it will not pour or circulate easily, it is
too thick for ultrasonic processing.
Use the Cup Horn for processing pathogenic, radioactive, and biohazardous materials in
complete isolation without probe intrusion. Because plastic tubes have a tendency to
absorb vibrations, it is preferable, whenever possible, to contain the sample in a stainless
steel tubes or glass tubes when working with a cup horn. To expedite processing, add
glass beads to the sample. If desired, crushed ice can also be added to the water inside the
cup horn, in order to optimize cooling. Processing samples in a Cup Horn will usually
take 4 times longer than processing with the direct probe intrusion method.