Abstract: Systems and methods for treating spools of fiber using recycled gas. Spools of fiber are placed in chambers which can be sealed for exposure to the treatment gas. When a chamber is closed and sealed the treatment gas is pumped into the chamber to a specified pressure temperature and pressure to react with the fiber. Upon completion of the reaction the gas is pumped from the chamber in order to facilitate the removal of the treated fiber. The gas can be evacuated with a vacuum pump and compressed to be stored in a pressure vessel for reuse. At this time the gas may be analyzed. If the concentration of a component is too low, the gas may be vented or it may be enriched so that it may be recycled; otherwise it is compressed for storage and the process is repeated.