38 artistApril 2016 http://www.painters-online.co.uk
opacities from thin, crystal-clear
translucency through glowing turbidity to
hard opacity, you will be able to make all
your pictures seem to glow with an inner
light.Application
Once one understands the physics of the
thing, it’s simply a matter of applying the
right paints in the best way.
In this respect the choices are pretty
simple. Paints, as any experienced painter
knows, are naturally opaque, semi opaque
or translucent, depending on the
pigments used to make them.
As a rule of thumb it is best to use the
right opacity for the job or, when you
wish to modify the opacity of a single
given pigment, to do so with one
medium. For example, to transition from
opaque to semi-opaque to translucent in
warm red you might choose cadmium red
(opaque), naphthol red (semi-opaque)
and perylene red (transparent). More
commonly a gel medium such as Gamblin’s
Neo Megilp is used to reduce incrementally
the opacity of the cadmium from opaque
to turbid to translucent.
Once you have chosen your paints,
think about their application. In most
cases the best ways to apply colours
optically are scumbling (dry brushing very
softly and evenly) or glazing (creating
viscous films of paint and medium). The
greatest painters, such as Turner, seemed
to move effortlessly between the two asA QUICK EXERCISE
Take a couple of old paintings that
are dry – your sky study from last
month would be a great choice for
one of them.
Glaze the first one with a colour of
your choice; you might choose a red
for a sunset or a rich brown for a still
life, for example. It should change
colour – look optically deeper, lose
some tonal range and provide some
interesting optical effects.
Scumble the second one with the
same colour, using a soft large area
brush. It should look softer and
mistier, losing much of its tonal
range.
Finally, optical painting starts with a
good underpainting, so if your
studies are underwhelming, try
working on a different set; strong
underpaintings are always the best
base for these techniques.SOME SIMPLE EFFECTS
Using the guidelines here, you should
be able to turn your hand to creating
pretty much any light effect you require.
Here are a few simple ones to get you
started, although as in any painting the
exact colours and mediums you choose
must depend on the job in hand.Shadows:glaze from turbid in the
umbra (darkest, sharpest shadow),
less turbid in the penumbra, to
translucent in the antumbra (most
diffuse shadow).
Rain:scumble over a dry base using
semi-opaque paint.
Fog:scumble a neutral semi-opaque
colour over a dry base. Using a
saturated underpainting will create
an illusion of great luminosity – a
foggy but bright morning, for
instance.
Strong light:glaze over a reflective
underpainting.
Soft light:scumble over a reflective
underpainting.
Sunsets and sunrises:glaze over a
dry underpainting with the ‘local’
light colour – a pinkish red, for
instance.
Nocturnes:glaze over a dark
underpainting to create optical
depth.Martin Kinnear working on a 47^1 ⁄ 4 71in (120 180cm) study.
Scumbling is a better choice than glazing for bigger canvases.
A resin glaze would simply get too sticky at this scalethey worked across their canvases.
Scumbling offers a soft haziness to paint
films; it’s ideal for pushing things back,
softening edges, suggesting glowing light
or indicating subtle semi-solid effects
such as rain or fog. Glazing is generally a
more precise technique for creating areas
of higher clarity, richer, deeper colour and
great optical depth. TA