Based on their mid-infrared transparency and tailorable thermo-mechanical properties, chalcogenide glass optical fibers have found numerous technological useful applications in the fields of optic and sensing. However they tend to suffer from mechanical limitations as compared to more conventional oxide-glass fibers, which impede their further integration into components where high strength is required. Reported here are findings on the mechanical properties of fibers based on the glass As2Se3, with a focus on unraveling how extrinsic impurities embedded in the native preform impact the maximum stress that the resulting fibers can endure. Preforms were prepared and subjected to four levels of purification (standard moisture removal, surface oxide volatilization, and synthesis over AlCl3 getter, followed by distillation) and subsequently drawn into fibers. To effectively decouple the real effect of impurity content on fibers strength from other peripheral parameters, such as manufacturing, handling or aging, each purification protocol was duplicated on one bare fiber and one fiber drawn with a protective coating. Weibull statistics on the strength of As2Se3 fibers were determined in both tension and bending. We demonstrate that coated and uncoated fibers follow a similar trend with purification. Specifically, oxide volatilization treatment increases the fibers resistance to failure, while the addition of AlCl3 getter in the melt without subsequent distillation degrades it. If further distillation is carried out the fibers strength improves only slightly as compared to oxide volatilization treatment alone. These results provide both insights into the interplay between chemical, optical, and mechanical properties as well as practical steps benefiting the continued utility of these glass optical fibers. (C) 2013 Elsevier Ltd. All rights reserved.