> My understanding of the process is that the tape is made to appear black by > making its thickness an odd number of half wavelengths thick in the visible > light region, but this then is not an odd number of half wavelengths thick > at the infra red region. It maybe that this applies to the die molecules in > the tape rather than the tape itself. This doesn't make sense, because you can stretch electrical tape to at least twice its original length (thus thinning it significantly) without seeing any strange optical effects. Besides: 1: It would require high precision control of the thickness 2: What about red, green, blue, yellow, white, etc. electrical tapes? Bob Ammerman RAm Systems. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics