Primers help to modify a surface to prepare for a painting medium to key onto it.

Unprimed, porous surfaces tend to absorb component parts of the paint being applied, both detrimentally affecting the finished artwork and the support. Grounds are usually applied to influence and aid the appearance of the final work.

Gesso
Traditionally, oil-based gesso was used as a prepared ground for oil painting, offering a smooth white surface upon which the artwork can be developed. As these types of preparations were harmful to the support, some type of size was applied first as a primer. Traditionally, this was rabbit skin glue.

These days, most preparations combine both primer and ground in one. Acrylic gesso is a good example and is one of my favourites when preparing surfaces. It is excellent for acrylic, oil, pastel and even watercolour and can be used on a wide range of surfaces such as card, MDF, hardboard, ply, Perspex, metal, etc.

For an even surface coating, I find that a small foam decorator’s paint roller is very effective.

There are also gessoes available that can be easily sanded to a smooth finish. Care must be exercised when selecting these as some are non-acrylic based and can only be applied to non-flexible surfaces. For best results with these, several applications are required, sanding between each coat.

Behaving differently
Absorbent ground is a very interesting primer that will make a wide range of surfaces behave with the absorbency of paper. This opens up a whole new area for artistic experimentation. I’ve painted it onto canvas and then worked watercolour on top with very exciting results.

Pastel ground is another useful material for the artist. It is a grit suspended in an acrylic paste and can be applied to a wide range of surfaces. The texture gives improved grip for pastel and coloured pencil work.

I’ve found that to get the flattest, smoothest application, dilute 50:50 with water. After stirring well, paint very fluidly with the substrate on a flat surface. Once dry, repeat this several times and a super, flat textured surface will be achieved.