In order to increase the mean time between failure (MTBF), improve safety and reduce leaks, system and maintenance engineers must match a material's performance and corresponding cost to process conditions. To ensure that the best suitable product is chosen for an application, engineers must either have a working knowledge of elastomer characteristics or have a resource readily available. William M Stahl from DuPont Performance Elastomers investigates the options available and suggests an easy evaluation process to help you make the right choice. © 2006 Elsevier Ltd. All rights reserved.