An extender, also known as a filler, in

printing ink Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thicker ...

technology is a white transparent, or semi-transparent, component whose purpose is to reduce the cost of the ink, by increasing the area covered by a given weight of

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...

. They generally have little colouring power.

Composition and Properties

Extenders are typically white inorganic solids. Their transparency in inks is frequently due to their

refractive indices In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

being similar to the ink, as opposed to opaque pigments, which are generally substantially higher.

Use

Extenders primarily serve to reduce the cost of the ink, but can also impart useful properties to it. They can reduce the colour strength of the ink without adding any white colour to it, which is useful if the pigment in the ink is very tinctorially strong. Extenders can also be used to adjust the ink's consistency and viscosity.

References

{{reflist Inks