An extender, also known as a filler,
[
] in
printing ink 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 powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...
.
[
] 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 the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...
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