Laser plastic welding process is based on a transparent plastic and an absorbant plastic. The carbon black absorber traditionally used can be replaced by a colourless, infrared absorbing medium thus expanding the applicability of the technique to clear plastics.

The infrared absorbing medium is either printed/painted onto one surface of the joint, encompassed into the bulk plastic, or produced in the form of a film that can be inserted into the joint. It absorbs infra-red laser light allowing an almost invisible weld to be produced between materials that are required to be clear or have a predetermined colour. The process is especially suitable where the appearance of a product is important.