THE IMPORTANCE OF UNDERPAINTING

An underpainting is a layer of under paint or under glaze onto which the painting may be applied.   The most common practice is to use an earth color, but any color can be used for the under painting.

BRING OUT THE TONE IN COLORS

Apply any color, regardless of how pale, onto a white background and the color will appear darker than it actually is. Some colors will appear bright because the surrounding art surface is lacking in color. Painting onto a white primed canvas can be off-putting as the first mark appears to have great significance. The artist will also find it difficult to judge a given color’s tonal value or to set the mood of the painting. For this reason, an under glaze will come in useful. 

TRADITIONAL UNDER PAINTING

A good way of killing the whiteness of the art surface is to apply a thin glaze of acrylic.  The most traditional color for the under paint is an earth color or Grey. This might comprise burnt sienna, burnt umber or a mixture of an earth color and blue, such as ultramarine. It does not matter if the under paint forms an even, flawless layer, as it will be painted over.

UNDER GLAZE

A preliminary drawing may be applied on top of the under glaze in chalk or a thin layer of paint, applied with a script brush.  Either will show beneath (or above) the under paint. Some artists prefer to work onto the under glaze without any drawing. Applying paint onto a neutral-colored art surface has many advantages as the true tonal value of colors are revealed; pale yellow appears pale, dark blue appears dark and white can be discerned against the background.

CREATING A MOOD

Any color can be used for the under glaze. Apply a thin layer of cadmium red and burnt umber for a warm, smoldering underpainting, ideal for snow scenes
The cool colors will appear to shimmer against the warm color.

SIZZLING COLORS IN ART

Similarly, a blue-colored under glaze. will create interesting contrasts against the overlying colors that are predominantly warm, such as a sunset. A yellow under glaze. will off-set violet hues, such as those found at the base of thunderstorms.

 Regardless of the color-temperature of the under glaze., this undercurrent will affect the appearance of the overlying colors in the painting, no matter how subtle. A snow scene will have a warmth about it; a sunset will appear to shimmer against the cool colors that poke through the brush marks.

TYPES OF UNDER PAINTING

Paint can also be applied upon an under glaze. that is similar in hue to the overlying paint in order to create harmony in the painting. Warm colors can be applied onto a maroon under glaze., or a sky sketch applied onto a violet under glaze. 

Setting the mood can often be determined by the color used for the under glaze. and the height of contrasts within.

HOW TO APPLY AN UNDER GLAZE

An under glaze. is easy to apply. If using acrylic paints, simply mix the required color with a little pigment diluted in water. Ensure there is ample amount of the glaze mixture to cover the art surface. Lay the surface flat and apply in large, sweeping strokes via a wide household brush. Allow the glaze to dry before embarking the painting.

MAKING THE PAINTING GLOW

A thin paint layer will permit the underlying white to show through, which will make the glaze appear to glow. A more opaque glaze will cover up this whiteness, and so will kill the effect. If wanting to retain this glow, avoid using titanium white within the under glaze. color mix; add extra thinning agent to any opaque pigment such as cadmium red, cobalt blue or burnt umber. 

Pigments that are translucent or semi-translucent in nature include: burnt sienna, ultramarine, pthalo blue, permanent rose and viridian. I personally like my under glazes to glow, adding vibrancy to the overlying paint.