Smooth and Smoother
|The combination of a
smooth surface and low absorbancy results in two
problems: poor brush handling and paint
application difficulties for the artist, and poor
adhesion of your paint to the primer.
On a too-smooth, low absorbancy surface, brush strokes tend to leave white streaks,
|rather than depositing the controlled applications of paint which an artist needs. Painters describe the surfaces as feeling "slippery" or "slick". Brush control becomes difficult, and careful paint application can be frustrating. Painters often compare it to "painting on glass".|
A well prepared surface, on the other hand, should be an aid to paint handling. A good painting surface should help the artist achieve the most nuanced paint application, accepting paint from the brush in a carefully controlled interplay of brush and surface.
If a gesso or primer has low absorbancy – which it should – then it needs to have a slight micro-texture in order to provide optimal receptivity for your paint. A little bit of friction is needed to "grab" the paint, pull it off your brush, and hold it in the places that you intended it to go. On a too-smooth surface, your brush slips across the surface without leaving paint behind where you intended. Too avoid this, the artist is forced to overcompensate by brushing extra slowly, applying extra pressure, "twirling" the brush, etc.
Prior to the introduction of steel-roller mills for preparing pigments and paints, the usual particle size of pigments and fillers in primer coatings was much larger than it is today; this gave primers the needed micro-texture for proper paint handling and adhesion. But largely due to steel-roller milling, few manufacturers today include large enough particles in their coatings; to do so demands more care and is more expensive. Frankly, we doubt that most manufacturers even know that they should. What's more, uniformly applying a coating with a very fine texture is more difficult than simply polishing a coating to a very smooth finish. Hence the proliferation of ultra-smooth polymer gessoes and slick "clay coated" bords.
Finally, some painters assume that it takes a glassy smooth primed surface to achieve a glassy smooth paint finish. But on a surface with a very fine texture and closely spaced particles, the viscosity of artists paints is usually sufficient for the surface tension of the paint to span the gaps between the particles without sagging into the troughs, allowing artists to achieve very glossy surfaces when desired.
You'll find more information about primers and interlayer adhesion of paints in our wood science glossary. To continue reading from where you were, close this window: