The cartographic documents realized for the 18th century Military Engineers Corps and the documentary sources related to its accomplishment are of historical, artistic and cultural interest. In this paper sources related to techniques, materials and its application are analyzed. Pigments and colorants named in this literature are described, specially recounted to the wash method. In these documentary sources are also described the code of colour applied depending on the represented element, the order or sequence of work and the mixture of colours. These cartographic documents had an eminently practical function, so in its accomplishment were following certain guidelines, which were allowing normalize its reading and interpretation. The documents studied contribute a significant information related to a collection which has to be conserved.