Unlike AS2, Arctic Silver recommends that AS3 be allowed a "run in" period of 50 to 200 hours to allow the thermal compound to thicken slightly to fill in the microscopic valleys of the processor core and the heatsink. The color of the AS3 thermal compound is slightly different from AS2 and the original AS as well. We observed that the color of the compound changes slightly under different lighting conditions, silver-green in color instead of AS2's silver color. According to Arctic Silver, the reason behind this is because AS3 makes use of three different shapes and sizes of silver particles as well as a small percentage of micronized boron nitride.