Reference is often made in tartan records to the Afflex (Affleck Slides).
Dr. Benjamin Afflex of Pittsburgh, PA was a very early member and 'Scholar' of TECA , the US sister-organisation of the Tartans Authority. He amassed an extensive collection of tartan swatches which he then photographed onto colour slides and gave them to the late Bill Johnston. Bill apparently had them enlarged to allow him to record the thread counts before his secretary - Diana Lindsay - entered them into his tartan database. It is assumed that that database was incorporated into the TECA one and thence into that of the Tartans Authority.
It's not known what became of the original swatches or the slide collection but investigations are ongoing.