Natural vs Synthetic Pigments: What's the Difference?

There is a scientific field behind producing the correct paints, and it can bring great joy to find out that your favorite colors are made from actual dirt or snail goo. In this article, I'll try to mix my experience with the science from the field.

When discussing synthetic pigments, the term 'hue' often comes to mind. However, while all hues are synthetic pigments, not all synthetic pigments are hues. For example, synthetic organic pigments—despite the seeming contradiction in the name—include petroleum-based families like Quinacridones. On the other hand, synthetic inorganic pigments refer to man-made colors that incorporate metals, such as cadmium-based pigments.

Generally, natural pigments have larger pigment sizes, less tinting strength, and worse lightfastness than modern synthetic pigments. This means that synthetic pigments not only last longer but also offer greater opacity and vibrancy, making them a preferred choice in many artistic and industrial applications.

The fundamentals of pigments are the following.

• Lightfastness - A rating of a pigment over a 100-year timeframe estimating how much it will fade 
• Opacity - A rating of how much light can pass through a paint
• Natural Pigment - Organic or mineral pigments that come from the Earth
• Synthetic Pigment - Created after 1800, these are usually made from chemically processed materials
• Organic Pigment - Petroleum or grown in Nature, it's possible to have "Synthetic Organic" pigments
• Inorganic Pigment - Made from minerals or processed materials.
• Particle Size - The size of the pigment determines many of the positive qualities of a pigment

What are lightfastness and opacity?

Lightfastness is an entire scientific field. Would the color fade if you were to take a pigment and leave it in the sun for a hundred years? Change colors? How does it react with sulfur? The pigments with the best lightfastness are generally synthetic because natural pigments generally experience more decay in a shorter time frame.

A lower lightfastness is better.

Opacity is also a scientific field, and it has a lot to do with the density of the pigments; how well the pigments are ground determines the paint's vibrancy and tinting strength. A finer ground pigment generally means a more vibrant color. Hand-ground pigments can't reach the same tiny molecular size as machine-ground pigments. That doesn't mean you can't have opaque hand-ground pigments.

Higher opacity is better.

What about particle size?

Each pigment is ground by hand or by machine. In general, machine-ground pigments reach a smaller particle size than hand-ground pigments. 

A smaller particle size means more pigment can fit into the mixture; a smaller particle size also directly correlates with higher opacity and tinting strength.

Particle size is inversely proportional to lightfastness. One can see the need to balance these factors.

Particle size is important because it determines paint intensity, opacity, lightfastness, transparency, and texture, basically all of it. So it's one of the most critical factors; it might be more important than paint load or pigment type.

However, particle size is either a range or a mean; different pigments also have minimum particle sizes that they can reach, so a direct comparison by particle size is not always reliable.

Natural vs. synthetic pigments

Pigment categories:

• Natural Organic: Such as Indian Yellow or Carmine Red.
• Natural Inorganic: Such as Burnt Sienna or Raw Umber.
• Synthetic Organic: Lab-made petroleum-based pigments such as the Quinacridone family.
• Synthetic Inorganic: Lab-made vibrant colors such as the Cadmium family.

So now we get to the heart of what makes the best paint.

There is an ongoing debate between natural and synthetic pigments among practicing artists. Many do not like synthetic pigments, and many do not know that their favorite colors are probably synthetic.

The main difference between natural and synthetic pigments is that synthetic pigments are man-made colors that result from a chemical process. 

Natural pigments are usually less opaque than synthetic pigments because of pigment size and produce more muted colors when mixed. When you are painting a natural landscape or portrait, muted colors are what you want.

Developed after 1800, synthetic pigments get a bad rap. Some primary colors like "Cadmium Red" and "Flake White" are not naturally occurring. So without synthetic pigments, some colors may not even exist. In addition, synthetic pigments can be cheaper, more consistent, and generally have better lightfastness than naturally occurring pigments because synthetic pigments aren't made from biodegradable materials.

Pros and cons of natural pigments

Natural pigments are naturally produced from the Earth. Natural pigments can be made from organic or inorganic material; the defining feature of a natural pigment is that it's not made in a lab. For example, Burnt sienna is made of kiln-dried dirt from Sienna, Italy. Lapis Lazuli, or French Ultramarine Blue, was initially made from semi-precious stones.

Natural Pigment Pros: Some Natural pigments are exact, historically significant colors that are hard to reproduce with synthetic pigments.

Also, some natural pigments' bulkiness is sometimes a feature. For example, consider natural colors like Van Dyke Brown, which was made from Cuttle Fish ink. Due to Van Dyke Brown's tinting strength, it requires multiple layers to get an opaque blackish tone. Also, because of its tinting strength, it mixes with other pigments without overpowering different colors. 

Natural Pigment Cons: 

• Bright, vibrant colors are not easy to find as natural pigments.
• Natural pigments are almost always more expensive than their synthetic counterparts.
• The color quality is inconsistent, and the pigment's characteristics do not always match what is advertised on the label.
• Natural pigments are derived from naturally occurring substances. Therefore, you never know what you'll get when you buy a natural pigment from a random manufacturer.
• According to Gamblin, a paint manufacturer, "Mineral-based pigments have larger pigment sizes and lower tinting strengths than modern colors."

Colors made with natural pigments

• "Ivory white" and "Ivory black" are made from Ivory.
• Indian yellow, one of Turner's favorite colors, is made from Cow pee.
• Carmine red is made from bug blood.
• Certain shades of purple are made from snail slime.

Natural pigment example: Umber is a mountain region in Italy with a specific concentration of manganese oxide. To make Burnt Umber from Raw Umber, it's quite simple. When the dirt from the area is burnt in an oven, it becomes Burnt Umber. 

Pros and cons of synthetic pigments

Developed after 1800 and often lumped with natural mineral pigments, modern science and technology have brought us many synthetic pigments, which can be durable, cheaper, and more brilliant than their natural counterparts.

Synthetic pigments are most commonly produced from chemical processes that involve aluminum, cadmium, chromium, cobalt, copper, iron, manganese, nickel, zinc, titanium, and calcium. 

Synthetic pigment pros: Synthetic paints have better lightfast ratings than natural pigments, meaning they don't fade or degrade as much in a 100-year timeframe.

Very bright warm colors like cadmium red, which are now essential parts of an artist's toolkit, are not naturally occurring. 

Colors made with synthetic pigments:

• Flake White - Lead
• Cadmium Organe - Cadmium
• Cadmium Yellow - Cadmium
• Cadmium Red - Cadmium
• Maganese Blue - Maganese

There are "hue" versions of many synthetic paints that are often more economical and less toxic, with their limitations.

Developed after 1800, synthetic pigments were born in a lab. Certain metals, like copper, go through different ranges of colors when oxidized, from orange to green. Some primary colors like "Cadmium Red" are not naturally occurring. So without synthetic pigments, some colors may not even exist. In addition, synthetic pigments can be cheaper, more consistent, and have better lightfastness than naturally occurring pigments because they aren't made from as many biodegradable materials.

Today, many art supply manufacturers mix natural and synthetic pigments to get a more economical product. However, this doesn't mean that synthetic pigments are of lower quality.

Synthetic Cons: 

• Synthetic pigments are more vibrant and opaque than most natural ones. For landscape painting, a neutral palette is what you want.
• Some synthetic pigments, such as pigments made from cadmium, can cost a ton.
• Synthetic pigments can also be cancerous. Read your paint labels. 

What is a "Hue"?

"Hue" is just another word for color. When it's mentioned in oil paint, it means that a more modern pigment has been used instead of the traditional one; for example, "Cadmium Yellow Hue" is the same color as "Cadmium Yellow" but made out of different synthetic pigments. It's important to note that "hue" does not have any specific connotation or meaning other than being indicative of the type of pigment used.

Hues are commonly synthetic versions of synthetic paints that are cancerous. That makes perfect sense because cadmium is a known carcinogen, and many of the original synthetic colors were invented long ago.

Made from lead, Flake White is the most famous cancerous synthetic paint.

Any paint sold in a store that risks your health will have a label. Many toxic colors, like Cadmium Red, don't have warning labels partially because they aren't over those legal limits.

Conclusion: The difference between natural and synthetic pigments

The main difference between natural and synthetic pigments is that synthetic pigments are manufactured colors that result from a chemical process. 

• Natural pigments are usually less opaque and produce more muted colors because natural pigments are natural Earth mined minerals or come from living organisms.
• Synthetic pigments are usually more vibrant, with smaller particle sizes and better lightfastness. Synthetic pigments are made in a lab; think cadmium, manganese, and zinc.