Mastering a colour—as such, its ‘domestication’—involves a weft of technological and symbolic relationships encompassed in the human ability to reproduce a visible colour using the techniques of textile dyeing. The Regimento dos panos or Regimento dos trapeiros (‘regulation of fabrics’ or ‘regulation of drapers’), published in 1573 and expanded in 1690, is a document made up of 107 chapters aiming to standardise the various stages of the production chain of woollen goods in Portugal. In the sections relating to the finishing of fabrics, the regulation carefully details the dyeing of the colour black. The main aim of this text is to discuss the four recipes presented in that document. The system presupposed a phase exogenous to the rules, since the fabrics had to be previously dyed blue (‘celestial blues’) by means of successive immersions of the cloth in a vat with indigo. The dyeing itself was achieved by mixing mordants and auxiliaries (alum, tartar, iron sulphate, and tannins) with a red dye (madder). The main conclusion is that the formulae presented do not constitute, in their general principles, a characteristic Portuguese methodology. In addition, the article includes an inventory of the raw materials used for dyeing in the Early Modern Age, produced, through a qualitative method, through cross-reference with other manuscript and printed sources, as well as an interpretation of their social and economic importance, and a systematisation of the types of Portuguese wools.