Pastels are made from three basic ingredients: powdered pigment, a binder that holds the pigment together, and often a filler like chalk or clay. The specific binder and its proportion to pigment determine what type of pastel you’re working with, how vibrant the colors are, and how the stick feels on paper.
The Three Core Ingredients
Every pastel starts with dry powdered pigment, which is the same coloring material used in oil paints, watercolors, and acrylics. The pigment is what gives pastels their color intensity. It gets mixed with a binder to form a thick paste, which is then shaped into sticks and left to dry.
The most common binders in traditional pastels are gum tragacanth, gum arabic, and methyl cellulose. These are all water-based adhesives that contribute almost no color of their own, so the pigment stays true. Gum tragacanth, for example, is typically mixed at a ratio of about 1 part gum to 30 parts water, creating a gelatinous solution that’s just sticky enough to hold pigment particles together without dulling them.
Fillers round out the formula. Chalk (calcium carbonate) and plaster are the most common, and they serve two purposes: they bulk up the stick to a usable size, and they lighten the color to create tints. A pastel labeled “light blue” is usually the same blue pigment mixed with more filler. Cheaper pastels tend to contain more filler, which is one reason they feel harder and produce less vivid marks.
How Soft Pastels Differ From Hard Pastels
The ratio of pigment to binder is what separates soft pastels from hard pastels, even though the raw ingredients are nearly identical.
Soft pastels have the highest concentration of pigment and the least amount of binder possible while still holding together as a stick. This makes them extremely vibrant and buttery to apply, but also fragile. They crumble easily and produce a lot of dust. For artists, this high pigment load is the whole appeal: soft pastels deliver color that’s close to pure pigment on paper.
Hard pastels and pastel pencils contain significantly more binder. The extra binder makes them firmer and more durable, which is useful for detail work and sharp lines. The tradeoff is less color intensity. Many artists use hard pastels for initial sketches and layering, then finish with soft pastels for rich, saturated color on top.
What Oil Pastels Are Made Of
Oil pastels use a completely different binding system. Instead of water-soluble gums, they rely on a mixture of non-drying oil and wax to hold the pigment together. A typical formula combines paraffin wax, stearic acid (a fatty acid found in many cosmetics and candles), and coconut oil. This gives oil pastels their creamy, almost crayon-like texture.
Because the oils in the binder don’t dry or harden the way linseed oil does in oil paint, oil pastels remain slightly soft and workable on the surface indefinitely. You can blend them with your fingers, layer them thickly, or even dissolve them with mineral spirits. They won’t produce dust the way traditional soft pastels do, but they also can’t be fixed with a spray fixative the same way.
Water-Soluble Pastels
Water-soluble pastels add emulsifiers to the formula so the marks can be blended and manipulated with a wet brush, similar to watercolor. These formulas typically include polyethylene glycol, which helps disperse the pigment in water, along with fillers like talc, kaolin, or calcium carbonate. Wax and stearic acid still provide structure to the stick, but the emulsifying agents allow everything to break down smoothly when water is applied. The result is a pastel that can work dry like a traditional stick or wet like paint.
Pan Pastels
Pan pastels contain essentially the same pigment and minimal binder as soft pastels, but they’re compressed into flat pans instead of formed into sticks. The manufacturing process reduces dust significantly while maintaining a very high pigment-to-binder ratio. You apply them with soft sponge applicators rather than pressing a stick to paper, which produces semi-transparent, easily mixable layers. They’re particularly useful for covering large areas with smooth, uniform color.
Pigment Safety
Because pastels are essentially pure pigment in solid form, the safety of the pigments themselves matters more than with most other art media. Some professional-grade pastels use pigments based on heavy metals like cadmium and cobalt, which can pose health risks with long-term exposure, particularly through inhaling dust.
In the United States, all art materials sold to consumers must conform to ASTM D-4236, a standard that requires a toxicological assessment at least every five years. Products that contain chronically hazardous ingredients must carry specific warning labels. Lead-containing surface coatings are banned above 90 parts per million. You’ll see a “Conforms to ASTM D-4236” label on any pastel set that has passed this review. Student-grade pastels generally avoid the more hazardous pigments entirely, substituting synthetic alternatives that mimic the color without the toxicity concerns.
Why Ingredients Affect Lightfastness
Lightfastness describes how well a pigment resists fading when exposed to light over time. This is entirely determined by the pigment itself, not the binder or filler. Some pigments, particularly certain organic reds and violets, fade noticeably within years of sun exposure. Others, like iron oxides (the earth tones) and cadmium-based colors, hold up for centuries.
Professional pastel manufacturers rate their colors for lightfastness, often using a star system or letter grade on the label. Standardized testing methods for pastels have been in development through ASTM since the 1980s, correlating lab exposure results with real-world fading. If you’re creating work meant to last, choosing pastels with high lightfastness ratings matters more than almost any other factor, since pastels sit on the paper surface with no protective varnish layer the way oil paintings have.