While WEST SYSTEM® epoxy has a long shelf life, age will eventually affect its handling characteristics and cured strength. When stored for very long periods, hardeners may turn darker (reddish to purple), become thicker and give off more odor. 105 Resin may lose some clarity and also become slightly thicker. Use extra care when mixing age-thickened products (stir extra thoroughly), and if color and/or clarity are crucial to your project, buy some fresh resin and hardener for best results. 207 Special Clear Hardener is specially formulated for clarity and flow. Continue reading →