SecurityGeneric MICR Fundamentals Guide 8-7Tampering methodsThere are several methods by which data on a check may bealtered. The security papers on which negotiable documents areprinted are designed to thwart these forms of tampering.Chemical tamperingMany inks can be affected by particular chemicals, makingchemical alteration of checks possible. These chemicals couldbe some combination of solvent and bleach. Certain inks can bebleached without materially affecting the paper stock. Other inkscan be selectively removed without affecting the rest of theimage.Select check stocks that contain materials that make altering theprinted transaction information difficult. For example, if ballpointpens will be used to complete the check, the paper shouldcontain indicators for ballpoint ink solvents. If organic dye basedinks, which are susceptible to bleaching, will be used, selectpapers containing a bleach indicator. (Because dry ink imagesare encapsulated in a plastic resin, they are almost impossible tobleach.)Check stock must also remain compatible with the MICR printingsystem on which it is used. Some chemical security features candamage printer subsystems. A marginally effective securityfeature could actually degrade overall document security.Mechanical tamperingMechanical alterations include erasing, picking ink out of adocument, and scraping to remove sections of the originaldocument. The part of the image that is removed is replaced witha section that looks similar. Mechanical alterations are oftenattempted on xerographic images.Ways to discourage this kind of alteration include:• Repeating critical information at several locations on thedocument. This turns a simple change of vital information intoan extensive modification of large areas of the document.
