Patent ID: 8865379

Claim:
A method of marking a straw comprising: a) defining a marking plane on a curved exterior surface of a straw, the straw having an axial body defining an axial passage between a pair of unsealed body ends and being formed from a polymeric matrix including an additive with electromagnetic radiation absorbance properties, the electromagnetic radiation absorbance properties including a maximum electromagnetic radiation absorbance wavelength and the axial body having a wall thickness of between about 0.1 mm and about 0.2 mm; b) matching the wavelength of a laser source with the maximum electromagnetic radiation absorbance wavelength of the additive in the polymeric matrix, wherein the additive with a maximum electromagnetic radiation absorbance wavelength comprises a photochromic dye with at least one maximum absorbance wavelength; c) generating a laser beam having a fluence within a fixed dimensional boundary of a beam spot; and d) focusing the laser beam spot at a plurality of pixel locations to produce permanent visible marks in the form of shallow divots and/or char marks on the marking plane of the straw, wherein the marked straw maintains sufficient integrity for sealing fluids.