If you have ever watched the late Bob Ross's Joy of Painting television program, then you are familiar with the term "liquid white." Before Bob begins his masterful paintings, he always lets the viewer know that his canvas already has a nice thick layer of liquid white on it. Then, he begins painting his heart out, all while gleefully "beating the devil" out of his brushes and sharing stories about his little forest friends.
Liquid white is essential to the "wet-on-wet" painting technique. You coat the canvas with a base coat of the liquid white, sometimes called liquid clear, and then paint over that. Whereas oil paints are thick and have a consistency of soft butter, liquid white is more of a creamy paint. The creaminess of the liquid white allows it to be painted on the canvas in even and smooth strokes.
Some people may get confused between liquid white and white gesso. They are not the same thing. Liquid white is only used with wet-on-wet painting. White gesso is a primer that also gets painted on the canvas before painting, but it must be dry first before beginning your painting. Gesso is used to add texture to the painting and to prevent the paints from being too absorbed into the cloth canvas.
Depending on where you live, finding liquid white can prove to be difficult. It can also be quite expensive. One way to help solve that problem is to make your own liquid white. Add some linseed oil to some white oil paint and mix it together until you get a slick, smooth paint. Then, coat your canvas and you're ready to paint. When using this home-made variation of liquid white, you will have to thin your other paints down with a little linseed oil as well for the best results.
A base coat of liquid white on the canvas lightens the pigments of the paints as they are applied to the canvas. This is especially important when painting a multi-hued scene, like a natural-looking sky. For example, in the upper corners of the canvas, you can apply a more liberal amount of paint and then drag the colour to the inside of the canvas, allowing it to fade as you go. The liquid white softens and mutes the colour for a more realistic look. The liquid white enables more layers to be visible in your painting. Because the first colour being applied on top of the liquid white will be slightly lighter, additional layers will add depth to your scene.
Bob Ross's liquid white is a secret combination of ingredients exclusive to the Bob Ross Inc. Liquid white is only usable with oil painting and other variations of the base coat medium are available, like liquid clear, liquid black and liquid opal. If you prefer working with acrylics, and you want to try a wet-on-wet approach to your painting, try the following: wet the canvas with a little bit of water. Paint a thin coating of gesso (whatever colour you wish) over the canvas. Spray a drying retardant over the gesso and start painting. This doesn't last as long as liquid white does in oil painting, but if you find the painting drying too fast, just spray more drying retardant on the canvas and continue.