A plastic joining method directs polychromate, non-coherent electromagnetic radiation through a transmitting plastic to an absorbing material that absorbs the radiation with the generation of heat. The heat is used to heat a bond line formed from the transmitting plastic and a substrate sufficiently to bond the transmitting plastic and substrate. A radiation filter of the same material as the transmitting plastic is used to reduce effectively unwanted absorption (and heat) in the transmitting plastic. Radiation focusing, masking, transmitting plastic cooling, bond line component drying, double pass welding, and additional bond line pressure are used to improve the bond of the resulting manufacture.