Article bearing machine-readable code imparted completely by laser marking

An article of manufacture, comprising a surface of a material comprising one or more polymers, wherein at least a portion of the surface bears a marked machine-readable code, the code comprising a pattern of markings comprising darker-colored areas substantially adjacent lighter-colored areas;

• wherein the lighter-colored areas exhibit a first set of CIELAB values;
• wherein the darker-colored areas exhibit a second set of CIELAB values;
• wherein the first and second sets of CIELAB values differ such that ΔL* between them is equal to or greater than 20 and equal to or less than 80;
• and
• wherein both the lighter-colored areas and darker-colored areas have features imparted by absorption of laser energy;
• wherein the lighter-colored areas comprises foaming, bleaching, oxidation, altered crystallization, etching, ablation and/or combinations thereof and wherein the darker-colored areas comprises carbonization, pyrolysis, reduction, a chemical change to an additive to the one or more polymers, and/or combinations thereof.

An article of manufacture, comprising a surface of a material comprising one or more polymers, wherein at least a portion of the surface bears a marked machine-readable code comprising darker-colored areas substantially adjacent lighter-colored areas,

• wherein the lighter-colored areas exhibit a first set of CIELAB values and the darker-colored areas exhibit a second set of CIELAB values that differ such that a Contrast is 20-50;
• wherein both the lighter-colored areas and the darker-colored areas have features imparted by absorption of laser energy, the lighter-colored areas comprising foaming and/or altered crystallization at or proximate the material surface and the darker-colored areas comprising carbonization, pyrolysis, reduction, a chemical change to an additive to the one or more polymers, and/or a combination thereof at or proximate the material surface;
• and
• wherein the one or more polymers comprise an additive selected from antimony tin oxide (ATO), tungsten oxide, titanium nitride, indium tin oxide (ITO), indium oxide, carbon black, and/or combinations thereof.