What is paint made of? How do paints get their colours? Explore how paint works with Dr Joanna Dowle (Senior Advisor at the Environmental Protection Authority). Learn about its history, chemistry, and how to use it safely.
This is an excerpt from the EPA’s Science at work series of science communication stories.
How paint works – brushing up on the science of paints
Paint comes in all the colours of the rainbow, can be made from clay, carbon, or cornflowers, and is used on everything from bridges to fridges.
We may take it for granted, but paint has been with us from the earliest days of our cave-dwelling ancestors, using paint to express ourselves, to communicate with others, and to decorate and protect all manner of objects.
The colourful history of paint
The earliest known human painting is an abstract cross-hatched drawing on a stone flake that was discovered in Blombos Cave in South Africa. It dates back to 73,000 years ago, but humans could have been painting even earlier than that.
Archaeologists found painting kits that are 100,000 years old in the same cave, containing bone and stone implements for crushing clay to create colour pigments, and shells of giant sea snails used as mixing pots. Some of these were covered in red or yellow clay powder, suggesting paints were produced at this site.
These days we use paints on buildings, walls, and objects to improve their appearance or prolong their life.
What is in paint
Paints contain three main ingredients:
- Pigments to provide the colour and opacity (hiding power)
- Binder which holds the other components together
- Carrier / thinner to make the paint spreadable
Sometimes other components / additives are included to modify and improve the properties of the liquid paint or dry film.
To make paint, the pigment (usually a fine powder) is mixed into the binder. This mixture is then thinned with the appropriate solvent or water to produce the right consistency of the final product.
How paint dries
'Watching paint dry' is usually a phrase reserved for very boring activities. But there’s a lot of interesting science that impacts when paint dries, which we can’t see.
Using paint safely
Now you know what’s in paint, here are some tips on how to use it safely.
- Preparation – read the preparation and application instructions, as well as the safety precautions before you start.
- Doing the job – keep a window open for air flow, and wear gloves and cover up to stop paint getting on your skin.
- Cleaning up – always dispose of paint in an environmentally friendly manner, never pour it down the sink or in stormwater drains.
- Storage – store all paints in their original tins or bottles, and in a secure place that children and pets can’t reach.
Read more about how to use paint safely >
How the EPA ensures paint is safe to use
The EPA regulates the chemicals used in paints under the Surface Coatings and Colourants Group Standards, and the Graphic Materials Group Standard. Group standards are approvals and safety rules for using a group of hazardous substances that have a similar nature, type or use.
One of the hazardous substances that paint can contain is lead. Although lead is not intentionally added to modern paints, some products can contain trace levels as an impurity.
In 2024, we reduced the levels of lead impurities allowed in paints to lessen any potential exposure to lead and further protect people’s health and safety.
Continue reading the story: How paint works – brushing up on the science of paints | EPA
