Physical properties of sodium silicate-based substances make them very attractive for commercial/industrial use. Liquids and solids based on sodium silicate and produced by PQ Corporation have a density from 1.6g/cubic cm. to about 1.4 g/cubic cm.
A very big difference between acrylic and oil paint is the drying time. Acrylics dry in a matter of minutes to hours and oils dry in a matter of hours to weeks! This is a huge factor when choosing whether or not to choose oils versus acrylics.
Oil pastels and pastels are similar in that they both have pigments like a traditional oil paint, and they both come in a stick format. The difference is mainly in consistency. Oil pastels use wax and inert oils, and as a result they have a crayon-like texture. Hard and soft pastels are chalky or powdery in comparison. Oil pastels offer a lot of benefits that stem from their adhesion characteristics, versatility, permanence and intense pigments.