While process-level raw material comparisons can be useful and interesting, it is important to examine the overall material impacts and not only look at the fiber-level impacts. Some materials require different processing steps that have greater loss rates, so only looking at one stage does not always give a complete picture.
Further, sometimes it is difficult to completely align the boundaries across different material production stages (compared to the full cradle-to-gate material boundaries, which are aligned to the finished material gate). For example, natural fibers are already in fiber form at the Raw Material Source. For synthetic fibers like polyester, the Raw Material Source is in pellet form. This is because for continuous filaments the input is pellet form. For staple fiber polyester, the fiber formation is included in the yarn formation stage. Therefore, comparing staple fiber polyester to cotton fiber is not an even comparison.