Most EVA-based HMAs do not have significant surface tack and are not pressure sensitive at room temperature. They need to be bonded at elevated temperatures by hot tack. They normally impart relatively short open time (typically less than 10 seconds) and fast set time. Open time and set time are primarily determined by the wax used – if it is included in the formulation, VA content, and the compatibility of EVAs and tackifiers. Typical waxes used in hot melt adhesive formulations are: synthetic, micro-crystalline and poly-ethylene wax. Waxes can significantly shorten open time and speed up set time. EVAs with more VA content will offer longer open time and slower set time.