Acrylic based white paint containing calcium carbonate, marble dust and other additives to produce a toothy surface to be used as a base for various types of painting.
Insoluble when dry.
A water based, water soluble, dense, opaque, flat white paint. Different to watercolor in that it contains calcium carbonate and more pigment to make it flat and opaque.
Remains soluble when dry
Gouache or Gesso
A question often asked, "When do you use Gouache and when do you use gesso - and what's the difference?" This article answers those questions and explains the difference between what seem like two similar materials.
Traditional watercolor practice does not include the use of white pigment. White areas in the painting are created by leaving areas of clean, untouched paper.
This technique produces clean, crisp contrast and a vibrancy that can’t be reproduced with opaque pigment.
Preserving white paper and contrasting it with strong dark tones and saturated colors is a sure fire way to make the focal point in your painting demand attention. However, once we move away from the focal point various white pigments can have amazing effects.
I’m a big fan of white gesso glazes to push back and obliterate areas of the painting. The milky, translucent glaze can take an area back to a mere suggestion of what was originally there, or can be used as a soft, subtle haze to reduce emphasis. These gesso glazed areas can also be worked over to reinstate some of the detail giving an interesting layered effect.
The important thing to remember when applying these gesso glazes is to make sure the edges, where the glaze finishes, are invisible. A spray bottle of water and a dry hake brush work wonders here. Feather the Hake brush quickly and gently over the gesso, drying the brush between every couple of strokes on an old towel. The secret is to work quickly and have all the edge gradations under control before the gesso starts to dry.
This detail shows how a soft gesso glaze was used to loose detail and create a soft, translucent haze. After the gesso glaze dried a suggestion of detail was added with watercolor and white gouache.
The top right and bottom left corners of this painting were pushed back with a subtle glaze of white gesso. This glazing results in a diagonal band of strength through the painting, breaking up the formal geometric layout.
Sometimes a more aggressive application of gesso can add animation and excitement to a painting.
A combination of soft glazes and rough aggressive brush strokes over the wings and tail of this parrot give a feeling of movement and panic. The glazes were applied after the watercolor had dried, then the rough brush strokes were scrubbed over the wet gesso glazes with a 1/2 inch bristle brush. Adding the strokes to the wet glazes meant, if necessary, I could use a dry hake brush to ease the brush strokes back into the glaze.
As well as gesso, white gouache can be used to add soft hazy areas of light to your work. Like gesso, gouache can be almost invisibly subtle or powerful and obvious. The big difference between gouache and gesso is that gesso , once dry, can be worked over, where as gouache remains forever soluble so, once dry, has to be left as is.
For this reason gouache is best applied towards the end of a painting whereas gesso can be incorporated at any time during the progress of the painting. The contrasting effect of a flat opaque area of gouache works beautifully with the transparency of watercolor. Because the gouache is so easily marked by a drop of water or a careless brush, applying it last or covering it once it is dry is good insurance.
The dark shadows under the striped awning are brought to life with a few marks of pure Ultramarine. In this case I used Ultramarine gouache straight out of the tube. Gouache dries to a flat, opaque finish and is more visible over darks than Ultramarine watercolor.
A Palette of blues from warm to cool. The first three are the ones I use plus, occasionally, Indigo.
The flat gouache sky (mixed from Ultramarine Blue and White Gouache) really makes the transparent washes of Quinacridone Gold, Alizarin and Permanent Rose appear to glow. The rocks and tree details were finished completely before the gouache sky was applied.
The light in the sky of this painting was added by wetting the entire sky, mixing some white gouache with a small amount of water then dropping it on to the area above the focal point and letting it spread. After the sky dried, tree details were carefully flicked in over the gouache with a rigger brush.
Don’t mix gouache or gesso on your watercolor palette. Gouache will turn your colors to an opaque mud if it find its way into your paint wells. Gesso will dry hard and immovable. Use an old plate or small spare palette.
Gesso and gouache have different properties. A question often asked is “When do you use gouache and when do you use gesso?” There is no hard and fast rule, but here are a few points to consider:
Gesso can be worked over once dry.
Gesso is permanent and insoluble once dry
Gesso works better as a thin glaze
Gesso can be applied at any time during the course of a painting
Gesso can be applied in layers one on top of the other
Gouache is best applied as a final step due to its easily damaged nature.
Gouache can be completely washed off if necessary
Gouache is more suited to adding fine white or tinted detail than gesso
The best way to experience the difference between these two white pigments is to experiment. They both produce some wonderful effects and if you haven’t tried them already, you will be surprised at what they can add to your work.
What is White Gouache?
Gouache is a water soluble pigment similar to watercolor with the addition of calcium carbonate to make it flat and opaque. It was originally used by graphic designers to produce artwork for photographing or scanning. A flat, non reflective surface was important but permanent, lightfast colors were less of an issue as, once photographed, the artwork was no longer needed. Modern artist quality gouache has better lasting qualities, but I prefer to stick to white and tint it myself with lightfast watercolors.
Gouache should be used on a separate palette so as not to pollute your transparent watercolors
What is White Gesso?
White gesso is an acrylic polymer based paint developed to prime painting surfaces. It is similar to white acrylic paint with the addition of calcium carbonate, marble dust and various other additives to make it a flat, toothy finish. There is also a watercolor gesso available designed to be absorbent enough to work as a ground for watercolor.
Gesso should be washed out of your brushes immediately, as once dry, it turns to an insoluble, immovable type of plastic.
Author: John Lovett