What term describes thinners or solvents used to alter the consistency of oils?

The term that describes thinners or solvents used to alter the consistency of oils is "diluents." Diluents are specifically substances that reduce the viscosity or change the consistency of a material, allowing for easier application or manipulation of the medium. In oil painting, diluents such as turpentine or mineral spirits can be used to thin oil paints, making them easier to spread on a canvas or adjusting their drying time and texture.

While mediums can also refer to substances that modify paint, they often have additional properties, such as enhancing gloss or transparency, rather than solely thinning the paint. Binders are components that hold pigments together, contributing to the paint’s adhesion and durability. Additives are substances added to provide specific qualities but are not primarily used for thinning or altering consistency. Thus, knowing these distinctions reinforces that "diluents" is the precise term for substances used to adjust the viscosity of oil paints.