Just the facts, ma’am
According to NY State Trooper, Scott Shepard “We come in contact with materials that are hazardous and need to be sealed to an evidentiary standard, and our standard is to have an embedded security heat seal”. When asked why the department purchased the two Seal- master Magneta 621 MG sealers for this purpose, Shepard replied “We have several of these machines and have used them for many years. They have always worked to standard and have an excellent track record for reliability.
Though relatively uncomplicated, the steps for achieving a code seal are interesting. To understand the process, however, one must understand the basics of impulse sealing. Impulse heat sealing is commonly used for joining thermoplastic materials such as polyethylene that require a moderate temperature to establish an effective seal. These materials are commonly used for evidence bags. Properly configured, an impulse heat sealer can quickly and efficiently join two layers of these thermoplastic materials.
The “how-to” of tamper-proof impulse sealing
Sealmaster Magneta impulse heat sealers are configured with a replaceable heating element made of a specialized material – usually a Nichrome alloy. This heating element is located in the bottom sealing bar. The Nichrome element is sandwiched between a Teflon insulating layer and a protective cover fabric. On the top sealing bar, the sealing rubber is laser-etched with an imprint of text and/or numbers that are specified by the police or fire department. After the materials to be sealed are positioned in the sealer jaws, the jaws close and are held in place by pneumatic or mechanical pressure. An electric current then momentarily heats the Nichrome element for a predetermined amount of time to achieve the necessary sealing temperature. The jaws continue to hold the bag in place until the heating and cooling cycle is complete (again, for a predetermined amount of time) to permit the welded material to cool and the imprinted seal to fuse fully. Largely determined by the material being used, heat sealing usually requires a specific combination of heat, pressure and time between each step. The result is a permanent, tamper-proof imprint that is physically embedded into the bag seal. Should a bag present itself without the imprint, it is very likely that the original seal was opened, trimmed off and resealed on a bag sealer that is not equipped with the official code seal – indicating the potential for tampering and/or alteration, and possible disqualification as evidence in a court of law.
Watch it in Action!