Laser marked articles with machine readable codes

A sheet of material that has been marked with a pulsed laser, the sheet of material comprising an outer surface and an inner surface separated by a core, wherein there is a first layer beginning at the outer surface and extending into the core less than about 60 micron, and there is a second layer that begins where the first layer ends, is at least about 5 microns from the outer surface, and begins no greater than 60 micron from the outer surface, and wherein the first layer is free of laser marking additives, and wherein the second layer has an average concentration of TiO2 within the range of from about 5.00% to about 12.00% by weight of the second layer;

• and wherein the sheet of material comprises a patch consisting of an area wherein the second layer is disposed at the outer surface of the sheet of material, and wherein the patch surface area is less than about 49% of the outer surface area of the sheet of material.