A method is presented for the treatment of pastels, which has been developed at the Instituto Português de Conservação e Restauro (IPCR) since 1992. It consists of blotter washing in a humid environment (using ultrasonic humidification) and drying process under controlled conditions. Other conservation methods that are described in the conservation literature are used in an experimental work and a comparison is established. The results show that the IPCR procedure is the most advantageous because it combines the least alterations of the pictorial layer and a greater effectiveness and facility in the removal of the paper alteration products. It is also described the method used for conditioning the pastels in a controlled dry atmosphere before rehousing them in their original mountings, using glass encapsulation.