NOVELTY - Method (M1) for forming a thin-film absorber comprises: (a) operating a furnace having an internal atmosphere containing a process gas; and (b) loading process gas material into a source container that is a part of a system configured to provide process gas to the furnace, where loading of the source container occurs without exposing the internal atmosphere of the furnace to external atmosphere present in the source container by solidifying process gas material to form a gas tight seal to separate the source container from the furnace.    USE - The methods are useful for forming thin-film absorber (claimed), useful in solar cells.    ADVANTAGE - The methods: are rapid; utilize low temperatures; and provide the thin film absorber with high-quality.    DETAILED DESCRIPTION - Method (M1) for forming a thin-film absorber comprises: (a) operating a furnace having an internal atmosphere containing a process gas; and (b) loading process gas material into a source container that is a part of a system configured to provide process gas to the furnace, where loading of the source container occurs without exposing the internal atmosphere of the furnace to external atmosphere present in the source container by solidifying process gas material to form a gas tight seal to separate the source container from the furnace, the seal is formed before the source container is opened for loading and external atmosphere enters the source container, the system comprises a shaped pathway configured to retain process gas material in a section of the pathway to solidify and create the seal, and the source container further comprises heaters in downstream pathway for liquefying the process gas material forming the gas tight seal to re-open a fluid pathway leading away from the source container. An INDEPENDENT CLAIM is also included for a method (M2) for forming a thin-film absorber, comprising: the steps (a) and (b) as above per se; and flowing material downward from the source container into a pathway having a first portion and a second portion, where the second portion is configured to provide resistance to flow out from the first portion, thus retaining process gas material in the first portion to solidify and form the seal.