Ultra thin metallic foils and organic films have been used as filters for the soft x-ray (SXR) and extreme ultraviolet (EUV) portion of the electromagnetic spectrum, particularly since the advent of space astronomy in the early 1970s. Much of the experience gained from manufacturing, testing, and using these filters is applicable to other applications such as microscopy, lithography, and holography. This review paper attempts to correlate data and experience from a large number of projects. Transmission data is presented along with discussion of causes of filter damage. Lessons learned are presented in the form of general guidelines for preventing filter damage.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.