Oils, Brushes, Surface, Varnish, and Palettes
Varnish
Varnishes in oil painting serve two purposes—First, they are used in the final stage of the painting to seal the painting for protection and to make the colors and values more true and luminous. Second, varnishes can be added in small amounts into your oil mediums as you paint to create vibrant colors. There are many varnishes to choose from, and once again, those using synthetic ingredients are toxic. The best ones have natural ingredients, such as Dammar Varnish— a mixture of pine sap resin and turpentine. Applying varnish should be done in a particular way. The odor is strong and harmful to you, so always put the final layer of varnish on your painting either outside or in a very well-ventilated area. It will need to stay in that area overnight for it to set and the fumes to dissipate. Your painting will also need to be covered in such a way that no dust, hairs, bugs, etc settle on the varnish after you apply it. It will remain tacky for hours. Finally, the videos you see online of people pouring half a bottle of varnish onto their painting and smoothing it around is incorrect. The sealing varnish layer should be very, very thin, with only enough varnish used to make the entire surface look ‘wet’.
Thickness
How thick your paint is, is an important consideration. Impasto refers to when your paint has lots of body, when you can see each brush stroke and the paint is laid on thick. One way to achieve this, is by using opaque paint colors. Not all oil paints have the same opacity or body to them. Some are quite thin, especially those labelled ‘hue’. The challenge with thickening your paint in this way is how much each paint alters the color.
Another way to achieve impasto, is through adding resins and mediums to your paint. These increase the thickness of the paint, but don’t adjust the color. There are a number of synthetic mediums for impasto, and those have very strong and harmful fumes. Natural impasto additives are odorless; these include waxes, gums, resins, and ground minerals and are referred to as Extenders. These add thickness but don’t significantly change the color of your paint; however, knowing what ratio of Extender to mix into your paint takes practice. Waxes (such as Carnauba, Castor, Beeswax) give your paint a consistency of butter, with the satin luster of a wax candle. Gums and Resins (such as Arabic and Guar) give a similar thick consistency, but the paint is more sticky/grippy when you apply it and it has more of a shiny luster. Mineral Extenders include Calcium Carbonate, chalks, Barite, Kaolin, Talc, Silica Quartz, Bentonite, and more. These will also add body and thickness to your paint, but won’t dilute the color. Most are sold in ranges from finely ground powder to more granulated—this shows up in your paint as you use it. For example, I use calcium carbonate (marble dust) in areas of my painting where sunlight is hitting stone to build up the paint thickly and give that area a ‘tooth’ like rough sandstone or stucco.
Oils
Many different oils are used in oil painting. When deciding which to use, consider ‘drying’ time, thickness (consistency), and how much it yellows over time. Old oil paintings are often yellowed or dark—this is partly due to the type of oil they used which has yellowed or darkened from exposure to light. Refined oils yellow and darken significantly less than unrefined. Below is a list of commonly used oils. ‘Drying’ refers to solidifying:
Flaxseed Oil: very slow ‘drying’ time, darkens values a lot. Refined Flaxseed Oil is Linseed Oil.
Linseed Oil: ‘dries’ faster than Flaxseed, but yellows over time.
Walnut Oil: the first of the pale oils, ‘dries’ slower than Linseed, but yellows much less.
Safflower Oil: paler and ‘dries’ slower than Walnut Oil.
Poppyseed Oil: very pale/almost clear, ‘dries’ very, very slowly.
Sun-Thickened Linseed Oil: exposed to sunlight, thick honey consistency, and dries quickly.
Stand Oil: Linseed Oil made with extreme heat in an oxygen-absent container. Dries slower, is paler, and runnier than Sun-Thickened. Creates an enamel, glossy finish w/less visible brushstrokes.
Burnt Paint Oil: extremely thick, makes the rheology very ‘grippy’ and viscous, with an enamel finish.
Black Oil: cooked at high temp. in a lead tray. Absorbs litharge—a mineral which decreases oxidation—which greatly increases drying time. A very, very dark oil like molasses.
Brushes
In art, variety creates beauty. One way to incorporate variety is in the size of brushstrokes. Paintings should include large brushstrokes down to small, and this is partly achieved by using a variety of brush sizes. Brushes can be grouped into two categories—synthetic and natural hairs. Natural hair brushes are from real animals and therefore more expensive. These natural brushes are softer, clean easier, hold more paint, and maintain their shape better over time compared to synthetic bristles. The most affordable natural bristle brushes are hog hair, but they aren’t very soft. If you are looking to achieve extremely smooth or hyper-realistic paintings, then softer natural hairs or more expensive synthetic brushes are for you. Most of my paintings are completed with hog hair and fairly inexpensive synthetic brushes. For areas of high detail, I have a few sables. Well-made synthetics can be just as soft as real hair—they just don’t hold as much paint and lose their shape much sooner. There is a definite difference in real hair and synthetic bristle brushes, but you need to decide what works for you—what your method calls for. I paint on thick-weave linen, and my early layers of paint are much too aggressively applied to use an expensive brush. I save those for smooth finish, fine-details areas/layers of my painting.
Surfaces
What you paint on—the substrate—is an important consideration. Traditional and typical substrates are linen, canvas, wood, paper, metal, composite boards, etc. You can paint on pretty much anything, as long as you follow certain important principles. First, the substrate needs to be sealed with an archival glue to prevent the oils in the paint and mediums from sinking into the material and spoiling it. Next, the glue needs a layer of primer (typically gesso, a mixture of a powdered mineral and glue). White gesso layers give a vibrancy to colors and a layer which paint can bind to. White canvases you see in the store already have these two layers, but thicker, more textured gesso layers can be added if you want more initial texture before painting.
The end result of your painting begins with the substrate. The textures in your substrate and gesso will be seen on the surface of your final painting (unless you build up very thick impasto paints). To achieve enamel smooth, hyper-realistic finishes artist paint on very finely woven fabric canvases like tight weave linen and cotton, or even on smooth wood or metal. Thick, impasto paintings are best done on thick-weave fabrics or wood. These hold paint better and are more stiff. If your substrate is really flexible your final impasto painting could crack if poorly handled years down the road. If you follow these principles your work will last. There are many oil paintings in museums on cardboard and paper that has lasted because the artist sealed and primed the surface.
Palettes
Painting palette’s come in all shapes, sizes, and materials. Wood, metal, plastic, glass, paper, etc. When picking a palette, consider three things—how easy it is to clean, how big it is, and what color it is.
Clean up: Oil paints will harden at different rates, depending on which color it is and how much medium/solvent is mixed into it. It will stay wet and workable much longer than acrylics. The piles of color on your palette can be left, but the working area of your palette should be cleaned after each session. I use a glass palette and scrape it with a razor blade. For a portable or temporary palette, I use a piece of MDF board wrapped in wax paper.
Size: If you use a small palette, you will feel cramped and your work will be affected. Also, if you are doing a large-scale painting (24 inches or larger), you will want an even larger palette than you typically use. If you haven't used a large palette before, I encourage you to try it and feel the frustration dissipate. Mine is enormous; however, a palette needs to be functional. I have smaller ones for going up and down ladders and plein air.
Palette color: I also encourage you to try palettes of different color. Painting on a white palette versus a dark brown or gray palette is a different experience and each artist has a preference.