The methods used by the Scottish Museum of Tartans for recording yarn count and color specifications of tartans are described. The origin of the colors used in old tartans was investigated and recorded, and a selection of the results is presented in terms of CIELAB coordinates and compared with the well-known natural dyes of the past. The changes in color caused by fading were noted, and the results analyzed to clarify the origin of the colors used in the modern, ancient, and reproduction tartans manufactured today. -- AATA