Working with Grounds
Artists who are concerned with making permanent paintings should consider carefully the quality of all layers of their paintings. They should be as concerned about the layers they do not see (size and ground) as the layers they do see (oil colors, painting mediums and varnish).
Ground is the foundation of an oil painting.
The first oil paintings were bannersoil colors painted directly on fabric. Probably painters soon figured out that linseed oil causes fabric to rot. To prevent deterioration, they sized fabric with animal glue. As painters met demand for ever larger paintings, they needed a new lightweight support. Enormous wood panels were difficult to move. Early Venetian oil paintings were painted on fabric prepared with only glue sizing. By adding a white oil ground, painters had a reflective surface that made their colors look brighter.
Oil grounds have been for five centuries a simple mixture of chalk (in Northern Europe) or gypsum (in Italy), white lead and linseed oil. Chalk is a calcium carbonate, which naturally occurs in fossilized shell deposits, like the White Cliffs of Dover. The premium grade of chalk was "champagne" used to make "Paris Chalk." Today we also call calcium carbonate chalk "whiting." Like gypsum, chalk does not make a suitable white pigment because of its poor color and transparency. For making gesso, opacity is not an issue because so many layers are applied. However, an oil ground on fabric should be no more 1/8 inch thick so only a few layers can be applied.
Gamblin Ground for Oil Painting makes a strong, bright foundation for oil colors. Formulated from alkyd resin, titanium dioxide, and barium sulfate, Gamblin Ground makes canvas and linen stiffer than acrylic "gesso" and more flexible than traditional oil primers. Barium sulfate gives Gamblin Ground its tooth. Titanium dioxide gives Gamblin Ground its opacity. Gamblin Ground does not contain lead.
For a video demonstration on applying Gamblin Oil Painting Ground,
click the play > button below.
Written instructions on applying Gamblin Oil Painting Ground download PDF.
Because the percentage of pigments is so much higher than in acrylic "gesso," painters need only apply TWO COATS OF GAMBLIN GROUND instead of the recommended FOUR coats of acrylic gesso. More coats can be added for smoother painting surfaces. Because alkyd resin is used instead of linseed oil as the binder, Gamblin Ground is more flexible and dries more quickly than lead/linseed oil grounds. Lead/linseed oil grounds must dry for six months and Gamblin Ground is ready for paint application within one week.
Gamblin Ground can be tinted with Gamblin Dry Pigments or Gamblin Artists Grade Oil Colors.
Before a oil painting ground is applied, the canvas is sealed with a size. The size seals the porous fabric and isolates it from the ground and/or oil paints. Linen and cotton will prematurely rot without a size layer. Only fabric supports need sizing. Panels only need to have a ground. Acrylic gesso does not require a size.
PVA Size (poly vinyl acetate glue), diluted with distilled water, is a contemporary size for fabric support. Conservation scientists recommend painters use neutral pH PVA size on linen and canvas instead of rabbit skin glue. PVA provides a good size layer that seals the fabric but does not re absorb atmospheric moisture, swell and shrink like rabbit skin glue does. Painters who want to paint directly on a size, apply one layer of PVA Size to the front and back of the fabric.
We acknowledge and appreciate the research of the Canadian Conservation Institute that helps painters and conservators identify the best PVA to use.
Rabbit Skin Glue is the traditional size for fabric support. Conservation scientists caution painters that rabbit skin glue absorbs atmospheric moisture on damp days and swells; gives off moisture on dry days and shrinks. This movement of the size layer can cause aged oil paintings to crack, according to the Smithsonian Center for Materials Research and Education.
Painters can add at least one coat of Gamblin Ground to canvas pre-primed with acrylic gesso to make a better painting surface for oil colors.
Gesso is Italian for gypsum (calcium sulphate dihydrate) which occurs naturally near salt deposits. Calcined gypsum, also called plaster of Paris, when mixed with animal glue, makes a luminous painting surface for egg tempera and for paintings on wood panels. Medieval painters applied as many as ten layers of gesso on wood panels. By painting alla prima with tempera on gessoed panels they could create "portable" frescoes. Gesso on wood panels makes a good surface for paintings that include burnishing and gilding techniques.
Gesso was not used as a ground for oil painting. The traditional primer for oil painting is an oil ground. Modern "gesso" was formulated by manufacturers of acrylic polymer primer about fifty years ago. Why they decided to call acrylic primer "gesso," a conservator suggested that the marketing department wanted to associate new acrylic primer with painting tradition so oil painters would use it. Whatever the reason, the name "gesso" continues to cause confusion.
Gamblin Traditional Gesso makes a traditional absorbent ground for oil paintings on panels. Gamblin Traditional Gesso is a dry mixture of rabbit skin glue, gypsum, marble dust, and titanium dioxide. Robert Gamblin recommends applying four coats Traditional Gesso to both sides of thin or poorly braced panels. Traditional Gesso is too brittle to use with fabric supports.
Additional information on sizes and grounds can be found in Sizes & Grounds.