Sufficient heat is generated for melting both the lower plastic and, by conduction, the lower surface of the upper plastic, thus, forming a joint. Laser cutting is achieved by rapid removal of molten material from the beam/material interaction zone. Most materials will melt due to the different physical mechanisms in play (see ' What is laser vaporisation? '), and in the molten state, the absorption of laser light increases. Granted, it was outside, but in a plastic baggie as I've been doing for over 20 years without incident. The molten pool is the smallest forming unit in the SLM. This process uses the intense energy of a laser beam to heat up material in a targeted manner and cause it to melt.