Oil paints were already a recognized medium in studio painting at the beginning of the 16th century, both in Italy and the rest of Europe. They are still widely used today, although they are not that easy to handle. Many people underestimate how crucial priming correctly is for achieving a successful result. The quality of the primer directly affects the longevity and appearance of the painting. In this article, you will learn everything you need to know about priming correctly and selecting the right materials.
What does oil absorption mean?
When painting over oil paints, care should be taken not to apply a paint with low oil absorption over one with high oil absorption, as this can lead to cracks. An exception is very thin underpainting, where this effect is less problematic.
Rigid painting surfaces and primers
Rigid painting surfaces are more durable and allow for more generous use of materials. With the right preparation, they offer a more stable base than canvas. Nevertheless, canvas remains the most popular surface for oil painting today. If you want to prime correctly, you should study the appropriate materials and techniques in detail to ensure the best adhesion and durability of the paint layers.
What is a plaster primer?
A gesso primer consists of a layer of glue or chalk that is applied to the painting panel for oil or tempera painting. Its smooth and white surface is particularly suitable for thin oil paints or glazes on a tempera underpainting. However, the primer must be isolated before applying oil paints, otherwise it will absorb the oil and turn yellow. To make it, glue is diluted with water to about half its strength. A single layer is usually sufficient. After isolation, the brush strokes glide smoothly over the surface and the paint is easy to spread.
How can you adjust a primer?
By adding sand, a thick structure can be created, which means less paint is needed because it already looks thicker. Priming correctly ensures that the paint layers adhere optimally and last a long time, preventing cracking and unwanted absorption of oil by the surface.
Primers for rigid painting surfaces
Acrylic gesso primers do not contain gypsum, but pigmented acrylic emulsions and can also be used as a base for oil painting.
Can you paint on unprimed rigid painting surfaces?
If the color of the painting surface is to serve as a tinted background, you can paint directly on it. However, if you want to preserve the pure color of the oil paint, you must work opaquely. To make the colors last longer, the painting surface should also be insulated.
Painting on glass
Glass that has been sandblasted on one side is particularly suitable as a painting surface because oil paints adhere well to it. Unlike with conventional painting surfaces, you start with the highlights and work your way through glazes and underpainting to the primer. A glass thickness of 4-6 mm is ideal. Before painting, the glass should be cleaned and degreased with spirit. Sandblasted glass allows the use of bristle or soft-hair brushes. If there are several layers of paint, each layer must dry completely before painting over. A practical method is to sketch the motif on paper and place it under the glass or sketch it on the front with a wipe-off all-purpose pen.
Flexible painting surfaces and primers
Modern oil primers usually consist of titanium white-pigmented, oil-modified alkyd resin primers that dry within 24 hours. To achieve a long-lasting color effect, it is important to prime correctly and use the right materials. Ensuring that the primer is evenly applied and properly sealed will enhance the painting’s stability and appearance.
Primers for flexible painting surfaces
Modern oil primers usually consist of titanium white-pigmented, oil-modified alkyd resin primers that dry within 24 hours. To achieve a long-lasting color effect, it is important to prime correctly and use the right materials.
Effect of white primer
White primers make oil paints appear particularly pure, especially with thin layers of paint. In traditional painting, it was used to illuminate thin, transparent glazes. Glazing techniques range from working directly with transparent paint on a white background to combining it with underpaintings.
What are imprimatures?
The selected oil paint is diluted with turpentine, applied and wiped off with a clean cloth after a few minutes.
Painting on a coloured ground
First, rough outlines are sketched out with charcoal and then slightly blurred so that only faint lines remain visible. By carefully brushing away the charcoal drawing, the oil colour remains unadulterated. The light areas are emphasised with titanium white, while shadows are created with a diluted mixture of burnt sienna and phthalo blue. After these first steps, a three-dimensional motif is created, which can then be further developed.
Painting on a medium to light-toned ground
The imprimatur consists of natural umber and burnt sienna, which are applied with a wide bristle brush.
Further tips: Brush techniques in oil painting