Watercolourists can rely on the white of the page and acrylic painters often just have a couple options available.
Whites in the Winsor & Newton acrylic ranges each has different properties.
• Titanium White is the whitest and most opaque of the whites and is recommended for general use. • Mixing White is a more transparent white with reducing tinting strength, making it ideal for strong tints, glazing, and toning down colours. • Iridescent White captures the unique effect of "light interference" and can be mixed with or painted over colours to create interesting pearlized effects.
But oils offer an array of seemingly unnecessary pigments to choose between. So why are there so many whites out there? Oil colour has been around a lot longer than acrylic and has therefore benefited from the developments of pigments over the years,” a few traditional pigments, non-toxic hues that mimic the lead whites, faster-drying whites formulated in linseed oil.
The main variations are due to several factors, including opacity, temperature bias, drying time and the toxicity of each individual pigment. As such, deciding on the appropriate white paint is often just a case of knowing exactly what purpose you will be using it for.
I was told to use Titanium White as a good all-rounder to keep in my paint box. It has a neutral appearance, doesn’t yellow when it dries and can be used to add highlights or block over darker areas thanks to the relatively high opacity of its base pigment, Titanium Dioxide. The downside to this is that it can overpower mixes and useless when it comes to glazing. “In cases where a subtle approach is necessary, a Zinc White or Mixing White, formulated primarily on Zinc Oxide, is more suitable,” advises Paul. The presence of Zinc Oxide can help reduce yellowing, too.
On occasions when a fast drying time is necessary, such as priming a canvas or board quickly before you begin, opt for a white containing linseed oil, like Foundation White or Underpainting White. “Both are formulated using linseed oil as opposed to safflower oil, making them dry quicker than most other whites and, therefore, suitable for painting lower layers,” says Paul. Linseed oil is more prone to yellowing than safflower oil, though, so bear that in mind if you use it in more visible layers.
The main difference between Underpainting White and Foundation White is that the latter contains lead, which remains a concern for some artists. Lead-based pigments can be harmful if swallowed and extended exposure to them may cause damage to the nervous system, bone marrow and more. Many non-toxic pigments have been developed.