The
synthetic whites
[Translation:
Anne Clerget]
French text
It is a safe bet that the first synthesises
of titanium white were slightly yellowish, (this is mentioned by several
sources), and the problem has been corrected thereafter. We
can also suppose that the poor preparation of some oils was showing through
more with this white, which is
one of the most dazzling pigments.
Insomuch as - this is not a joke - we will advise against leaving in the
open air, during summer nights, a surface freshly painted with this pigment:
it will attract nocturnal insects confusing it with a source of light.
The opposite picture allows comparing a titanium white
to a
lithopone white, blend of
zinc white and barium white supposed to be rather neutral.
Titanium dethroned lithopone white and the other
whites for many uses because it is simultaneously :
* very bright
* permanent
*
perfectly stable when mixed (which is not necessarily the case for lithopone
white, according to the quality of the pigment washing)
*
noticeably toxicity-free (Read
Zinc white, titanium white : toxicity).
Its
disadvantages :
* it is
a bit lumpy while being bound. Because of its saturation time, it is better
to treat it first on the palette when the painter makes the paste himself
(see
To separate or not the binding agents and the pigments).
It has to be mixed with the palette knife a bit more lengthily and
vigorously than the other colours. Besides this technical detail, it does
not pose any particular problem. It is only slightly more absorbent than
average. Read
passage in Poor absorption.
*
sometimes, it is too blue! So, it is often necessary to add a very small
amount of yellow.
* it is
a bit expensive but its cost/hiding power ratio is more interesting than the
lithopone white's.
Despite these
small disadvantages, the contribution of this pigment to painting processes
is huge. Likewise, it is recommended to add some titanium to natural whites
like Meudon white at the moment of
gesso preparation.
See
Titaniums.
Zinc white
Composition, extraction, details :
read the article of the glossary.
During a long
time,
zinc white had a reputation
of being cool and long-lasting, contrary to all other zinc colours, which
have been abandoned. It generated a lot of interest despite its excessive
transparency because the nascent titanium was considered too warm (see
above), like the
natural whites, which are
naturally greyish or yellowish.
Today, the
interest of pure zinc white seems rather limited. Some varieties contain
sulphur, and it may pose a problem of compatibility with lead siccatives in
oil painting if the pigment wash is of poor quality. Moreover, it is
quite transparent. For this
reason, its use is really less comfortable than the use of titanium white.
It may help, though, for the application of
velature
and other
glazes.
Lithopone white, contains a
sulfurated variety of zinc white, and is used in artistic painting only for
backgrounds.
Zinc oxide
and the arts of fire --> read
the article of the glossary.
Recommended readings:
Zinc white on Pourpre.com
Lead, flake or silver white
It is a
lead-based mineral white, treated in a
specific chapter.
Lead is a
violent poison.
Bismuth white
Bismuth-based
(very heavy metal, see
Periodic table), it is a
very transparent pigment preferably used for
glazes.
It must be
ground in a particular way, so that it does not turn yellow. This is a
Flemish process, mentioned by Dr de Mayerne. One cooks a portion of raw
sunflower oil
with
litharge, then the pigment
is added when the blend is cold.
Barium and silica whites
They are part
of the whites known as "natural" because they are very present in the white
earths. However, a treatment is required for their extraction.
Read the article about white earths.
Tin white
This
tin
oxide(PW15)
is not a very common pigment. It is not easy to find it in catalogues. It is
actually a compound SnO3 (stannate)
which is associated with other compounds to form
salts. We do not know if it
is also sometimes used pure in painting; but this use would not be more than
marginal, anyway.
It is mainly
used in the fabrication of
ceruleum blue (opposite
picture), or at least of some versions of this colour. In this blue, it
"breaks" the strong hue of cobalt with which it is associated. Tin white
brings all its subtlety to this colour.
Chlorine
The element on the periodic table
Article of the glossary
This is not a
pigment. However, this substance allows in some forms (notably Javel
water), to bleach yellowish cloth or paper, but also to "open a white"
in watercolour - and other water-based paints - on this account, it has to
be mentioned in this article.
Claude
Berthollet discovered discoloring virtues of chlorine in 1791. By doing
such, he changed profoundly the chromatic world of fabric because, formerly,
it was quite impossible or at least very difficult to obtain a truly pure
and permanent white (the most common method was the field bleaching,
supposing a heavy implementation and not very effective).
Javel
water is chloride or sodium or potassium
hypochlorite - an ordinary salt containing this gaseous
halogen nonmetal: chlorine
- in an aqueous solution. Its name comes from the name of a village (that
became a district of Paris), where the production site was established. When
air-dried, it produces a discreet crystal-clear
precipitate
which is not
noticeable during a housework use. This salt puts itself back in solution in
the presence of water.
We have been
informed that the use of chlorine for bleaching is not always done within
normal safety and health conditions in some developing or third-world
countries (see
The shade of "white" paper in papers).
Go back
to the top of the page
