Rembrandt Soft pastels are made on the basis of the finest kaolin, also known as China clay or pipe clay. In contrast to the binders of the paints, kaolin does not help in the adherence to the ground but holds the pigment in the pastel together. The ratio of pigment-kaolin helps to determine the consistency of the pastels.
Using a mixer the dry raw materials are mixed with water to a semi-wet mass from which the pastels can be pressed. This mixing should be carried out with the greatest of care. If the mixing is done for too long, too short, too quickly or insufficiently, then the final colour will be different from the standard colour, or hard pieces may get into the pastel which may cause scratches in the painting. As the water absorption for each batch cannot be predicted accurately, and because the right amount of moisture is crucial, the pastel maker determines the consistency of the mass for each colour by hand. It is only after years of experience that such a skill is perfected.
Colour inspection
In order to determine whether the colour is good, the pastel maker produces a pastel by hand. This is dried (the colour of the wet mass is not the final colour) and applied on paper alongside the standard colour. Even with the slightest colour deviation the pastel ingredients would have to be adjusted.
Drying and labelling
Once the pastels have been made from the ingredients, they are dried and labelled. The label acts as protection during transport and provides information on the colour, the pigment used and the lightfastness.
