Mixing with water can be done in two ways:
- Thin the paint a little with a small amount of water. Here the
water and the paint have to be mixed well little by little to
acquire a homogeneous mixture. The emulsion between water and oil
does not occur spontaneously, but needs to be stimulated.
- Add water to a little bit of paint to create a very thin and
transparent paint with a water colour effect. If, however, a great
deal of water is added, then the greatly thinned oil offers
insufficient protection for the pigments. This is not a problem for
a first drawing which is later painted over with a thicker paint or
paint thinned with a medium. If only greatly thinned paint is used
for a painting, then it is recommended to add at least 20% Cobra
Painting medium to the water.
Alla prima means that the painting is painted 'wet-into-wet'. In
this technique you mix colours not only on the palette but also on
the painting itself and the paint is applied against and over one
another. A painting must be finished while the paint is still wet
and so the painting will be built up of a single layer of paint.
The paint can be applied pure or with the same thinner all the
time. In the latter case the most durable result is produced using
Cobra painting medium.
With layered painting you build up the painting from various
layers. A next layer can only be applied once the previous layer is
dry enough to ensure that it will definitely not dissolve. With a
layered painting a technique is followed that is known as 'fat over
lean'. Every subsequent layer must contain more oil.
The first layer must be applied lean. For this the paint is
thinned with water. During the drying of this layer no compact film
of paint is formed, but rather a porous one. Oil from a following
layer will therefore be absorbed by the underlying lean layer and
so when drying will adhere within the numerous pores. This helps to
create good adhesion between these two layers. As an underlying
(lean) layer abstracts oil from the top layer, it has to be ensured
during painting that the underlying layer has relatively more oil.
If this is not the case this will affect the quality of the
In relation to the mutual adhesion the fat over lean principle
also has a function in absorbing the tension between the various
layers of paint. The painting is constantly exposed to movement; on
the one hand due to the flexibility of the grounds such as the
artist's canvas, and on the other hand through, for example,
changes in temperature and air humidity. For the durability of the
painting it is therefore important that all paint layers can absorb
these movements. The more oil the paint layer contains the more
elastic it will be once dry.
If a painting consists of several layers whereby the under most
layers contain more oil than the one directly above, therefore
against the fat over lean principle, then the less elastic upper
layers will in the course of time pull away from each other by the
more strongly moving underlayers. Once this is noticeable to the
human eye we refer to it as crackling. This can be avoided by
making every subsequent layer a little fatter. The fat over lean
principle can therefore also be interpreted as 'flexible over less
flexible'. This clarifies immediately why a layer of paint must be
sufficiently dry before the next layer can be applied. A layer that
is not sufficiently dry throughout is often too elastic for the
subsequent layer, with again possible cracking as a result.
The number of layers applied to make a painting is of course a
personal choice. It is advisable, however, to thin the first layer
with water. The more water, the leaner the layer of paint.
Once the first layer is sufficiently dry, the second layer of
paint is applied. As of this point there are various possibilities
for continuing further:
1. Thin each subsequent layer with increasingly less water; each
subsequent layer therefore contains relatively more oil. You can
eventually end up with pure paint.
2. Thin the paint for the following layer with painting medium. A
good medium consists of three components: oil, resin and solvents.
The oil makes the paint fatter, whilst the solvent ensures that the
paint does not become too fat. The third ingredient resin increases
the durability of the paint layer. If you build up a painting in
more than two layers, you can mix the medium proportionally with
water from lean to increasingly fatter. The larger the relative
amount of medium, the fatter the mixture. In the final layer you
can mix the paint with pure medium.
Whether a painting is painted wet-into-wet or in layers, a
glazing can be applied as a final layer.
A glazing can be applied as a final layer; this is a transparent
layer of paint the effect of which can be compared with that of a
tinted plate of glass placed over a picture: the picture itself
does not change, but the colours do.
The reason for applying a glazing may be that a painter is not
satisfied with certain colours and wishes to change these without
having to paint over the particular section again.
Another reason may be that the painter is deliberately looking to
achieve the visual effects of layers of glazing (an enamel-type of
top layer and deep colours) and to deliberately use an
underpainting as a basis of bringing a painting into the right
colour using one or more layers of glazing.
Do not allow brush strokes to be visible in a glazing as you will
continue to see these of the underlying layers through the
transparent paint; a glazing medium therefore has to flow. Thanks
to this property you can also make flowing colour transitions in a
Of course a layer of glazing has to be more elastic than the
underlying paint film as here, too, the 'fat over lean' rule has to
be followed. You cannot always foresee exactly how many layers are
needed to come to a satisfactory result. Ensure therefore that the
paint is never too fat, so that any subsequent paint layer is then
still able to bond.
Yes this is possible, providing the following is taken into
consideration. By adding a small amount of paint to water you
produce a very thin and transparent paint. However if a huge amount
of water is added, then the greatly thinned oil does not produce
enough protection for the pigments. For a first sketch where later
thicker paint or paint thinned with medium is used to paint over
it, this is no problem.
If a painting is made only with very thinned paint, it is
recommended to add at least 20% Cobra Painting medium to the water.
The ground does however have to be prepared for oil paints.
Impasto is a painting technique whereby the paint is applied on
to the work in very thick layers. The Impasto technique allows
reliefs to be incorporated in the paint layers. Use a palette knife
or a brush for this technique.
Cobra is a pure oil paint and can be used over traditional oil
paint. If it concerns an older painting that is fully dry, it is
recommended that you first wipe it with white spirit or turpentine.
The way one continues on the painting depends on the composition of
the latest layer of traditional oil paint. The 'fat over lean' rule
must also be followed here, whereby it can be assumed that both
types of paint are equally fat. The latter also applies to ordinary
painting medium versus Cobra water-thinnable painting medium, and
standard glazing medium versus Cobra water-thinnable painting
Cobra water mixable oil colour is a pure oil paint and can be
thinned using solvents such as white spirit and turpentine. It is
then no problem mixing with traditional oil paint. Once the old
tubes of 'ordinary' oil paint are finished, you can change from
solvents to water. If, however, only water is used, the water
mixability will decrease as more traditional oil paint is added to
Cobra and brushes will be more difficult to rinse. In order to be
able to thin a mixture of Cobra and traditional oil paint with
water the paints have to be mixed well using a palette knife and a
large part of the mixture has to consist of Cobra water mixable oil
paint. The ratio may vary per colour.
This does indeed happen sometimes and is referred to as binder
separation. This occurs particularly when there is air in the tube.
If so desired, the oil can be mixed back into the paint, or
absorbed by for example a tissue.
The Cobra brochure gives an example of a basic palette. Another
possibility is to work with just using primary colours plus white:
Primary Magenta 369, Primary Cyan 572, Primary Yellow 275 and
Titanium white 105. Already with these 4 colours a wide range of
colours can be created.
If you would like extensive information regarding colour and
mixing colours, please ask for a copy of the Talens booklet