Inert pigments There for reasons other than color
These are the main inert fillers that are used to impart various
physical properties other than color such as opacity or texture, or
simply to make the paint handle better. Over used these same substances
can be regarded as adulterants. All these substances should be used in
the minimum concentration possible to enable the maximum color
concentration in the circumstances.
The most important inert filler for the artist to use. It is synthetic
chalk that is more pure and softer than Whiting, and is recommended for
most applications that require chalk.
All of the various forms of Calcium Carbonate such as chalk, whiting,
marble dust, limestone and so on are all chemically identical,
differing only in crystalline structure and degree of impurities.
Precipitated Chalk is the most pure form of Calcium Carbonate
It is an ingredient in Gouache, Pastels, and Chalks. It can be used as
a base for making lake pigments. It makes particularly fine gesso's.
Whiting is ground natural chalk. It varies considerably in purity and
is often labeled with such names as Gilders Whiting that differentiate
the various qualities. It is less expensive than Precipitated Chalk and
tends to be coarser. It is most useful for making hard pastels or for
gesso's that require its particular color or texture. Mixed with
Oil it makes putty. The best grades are called Paris White.
This name covers all forms of Calcium Carbonate on the Earth and makes
up 4% of the Earth's crust. As a pigment it is different to other forms
of the mineral and that is due to its crystalline structure. It is the
form of Calcium Carbonate that is best suited to making modeling pastes
in Acrylic and is a useful addition to gesso's for its tooth.
iAn impure form of Calcium Carbonate that can come in a variety of
colors. It is a useful additive to very intense organic colors, toning
them down and improving workability. Can also increase the brilliance
of some dark colors like Viridian.
Fine chip (like in Terrazzo) can be used as a
textural additive to Acrylic paint
The finest whitest grade of natural chalk, significantly whiter than
the grades sold as Gilders Whiting (see above).
Kaolin (China Clay)
A fine white clay that originally comes from weathered Granite. It can
be calcined to produce the whitest shades, It can impart smoothness and
other characteristics in Pastels, Chalks, and Gouaches. Do not accept
just any offering as it is possible to find particularly white grades
but they are not necessarily easy to find.
A natural Magnesium Silicate that has
properties between Talc and asbestos that is used by paint
manufacturers because it aids in holding pigments in solution and helps
in the formation of strong paint films. Not recommended for making
paint in the studio.
Talc has many uses for the artist. It is firstly a soft easily carved
stone for sculpture. As sticks it is called French Chalk and writes
well on steel for marking out metal for fabrication and then as a
pigment powder it can be useful when making paints. It is good for
increasing the opacity of very weak colors while minimizing the chalky
look of using straight Precipitated Chalk. In Pastels its greasy feel
can modify some pigments that tend to set to too hard a pastel. It can
exhibit a pearly luster in some circumstances too.
Silica / Quartz
Available in various particle sizes from fine powders to sand to small
pebbles. Used to provide tooth or visual texture to paint. The larger
sizes should only be used with acrylics.
Aluminum Hydroxide is used as an inert base for precipitating dyes in
the making of lakes. Manufacturers like it because it imparts good
brushing qualities to oils and so is often found as an extender. The
most transparent of the various bases for precipitating dyes for
making lakes so is most suitable for delicate colors, An excellent
extender for the Pthalocyanines. It is made from Bauxite.
Aluminum and Potassium Sulfate is found naturally as Kalunite. This
was the material that lakes were precipitated onto until recent times.
Is readily available from pharmacies.
Synthetic Barium Sulfate is sometimes called
Permanent White. It is a common extender for Pthalocyanine
pigments where its use is regarded as beneficial to pigment properties.
It is commonly co-precipitated with Cadmium
colors as the two are chemically similar and hard to separate. Industry
standards allow up to 15% Barium Sulfate in Cadmium colors. It is more
expensive to produce chemically pure Cadmium and this is why there is a
premium on the pigment.
It can be used as a base for precipitating strong dyes in making lake
pigments and is an excellent white to use for Watercolor, Gouache, or
A white pigment prepared from Blanc Fixe (see
above). It is Zinc Sulfide and Barium Sulfate with a little Zinc Oxide.
It is a common pigment for exterior paints and is often added to Zinc
White to increase opacity.
Natural Barium Sulfate that is a heavy inert pigment with low oil
absorption, and easy dispersibility that is a popular (among
manufacturers) adulterant in paint. In oil it is nearly transparent but
does cloud the color just a little. It should not be confused with
Blanc Fixe which is the synthetic version of Barium Sulfate but has
quite different properties (see above). The Barium Sulfate in many
Cadmium's is in the form of Blanc Fixe (see above) or Lithopone (see
A gray lightweight volcanic scoria which is ground into a powder and
used in paints and grounds to provide a toothy textural surface.
Infusorial Earth / Diatomaceous Earth
This type of silica is ground from a rock that is the fossilized
od Diatoms, a single cell algae from millions of years ago. It is found
in chalky deposits and is commonly used in abrasives, cleansers,
toothpaste's, and filters. It can be used for making paints to coat
papers for pastels or other gesso's and grounds to modify tooth.
Used to impart sparkle to paints it can weaken Oil Paint films,
especially where the mica particles are larger as the mica continues
over time to cleave into smaller flakes. The finest grades of Mica
flakes seem to avoid this problem. Mica Titivates are stable Mica
pigments giving a wide range of effects including metallic, iridescent
and diffraction. For more info
on the mica pigments click here.
A type of clay derived from volcanic ash with occasional use in
Pastel making. It has the ability to absorb large amounts of water (and
swell accordingly). This quality may have some use in experimental
A special kind of phyllosilicate mineral resembling Mica which has the
unusual property of expanding when heated to form a lightweight porous
substance. Most people are familiar with the larger sized materials
used in landscape architecture or medium sizes used in some kinds of
kitty litter but it can be found in many sizes down to half millimeter.
The smaller sizes up to 2 or 3 mm are most useful for mixing into
acrylic for textural effects.
Small glass balls of various diameters that are particularly good in
Acrylic but can be used in oil as well.
Can be a very effective textural additive to acrylic as the resin
pellets and the dried acrylic are similar in refractive index and the
Ketone requires alcohol to dissolve so is very permanent as a solid
inclusion in the acrylic. Has a different look to glass beads.
Go to pigment main page
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Go to Historic pigments
Go to Red pigments
Go to Iridescent and Metallic
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