AbstractPolyvinyl chloride is rapidly becoming recognized as a versatile polymer. It has a unique ability to accept additives, and the properties of the finished article often depend more on formulation than the resin itself.A wide variety of chemical may function similary in PVC, yet processors often have to compromise in selecting one additive over another. For example, both tin mercaptides and metal carboxylates function as thermal stabilizers. The mercaptide is superior as a thermal stabilizer while the carboxylate offers better weathering stability. Today's market tends to compromise at the expense of weathering. To compensate, high levels of reflective pigments (TiO2) are used.Recently, we initiated a research program and discovered a class of compounds which provide excellent weatherability with processability comparable to the highly‐efficient tin mercaptide. This cost‐effective development allows reduction of TiO2levels by 25–50%. In addition, dark pigmented profiles remain relatively undeveloped because of serious weathering problems. Accelerated weathering and outdoor exposure tests demonstrate this technology is quite effective for UV stabilization of dark brown sy