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> emitted by almost all printers I believe it's only by some copiers and laser printers, not inkjets for example.

• einr 4y ago
  Indeed if they had the identification code they would have been able to pinpoint the model and serial number of the printer, but they haven't released that information -- only that it is a HP printer with HP 302 or 304 model ink cartridges, which I assume is based on analysis of the chemical composition of the ink.
  • dhosek 4y ago
    They also say, “Ink cartridge type HP 302 or HP 304 color cartridges are used.” [italics mine]. In that case, they may have the yellow watermark and just aren’t saying so.
    • jcrawfordor 4y ago
      To my knowledge only laser printers participate in the MIC scheme. While the boundaries of the program are somewhat unknown, just from a technical perspective inkjets generally struggle to produce low enough coverage for the marks to not be pretty visible to the eye (bleed of inkjet inks prevents high-pitch halftoning performed by laser printers to produce very low coverage).