Scientists made the world’s whitest white

Scientists announced BaSO₄ (Barium sulfate), the whitest white ever developed, in the form of a paint. BaSO₄ is practically impervious to the colours of the visible spectrum. Even better, while it’s a very cool invention in the colloquial sense, it’s also cool in the thermal sense. The new paint can actually cool surfaces on which it's applied, potentially reducing the need for climate-unfriendly air conditioners.

Most outside paints actually warm the surfaces to which they’re applied. While there are already some reflective paints on the market, they only reflect 80-90% of sunlight, not enough for a cooling effect.

By contrast, BaSO₄ results in 98.1% of sunlight bouncing off.

If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts. That’s more powerful than the central air conditioners used by most houses.

Scientists tested BaSO₄ using thermocouples, high-accuracy devices that measure voltage to determine temperature. They found that at night, BaSO₄ surfaces are -7.2º C. cooler than surrounding air.

Bottom of Form

The team crammed as many tiny BaSO₄ particles into the paint as possible. Although a higher particle concentration is better for making something white, you can’t increase the concentration too much. The higher the concentration, the easier it is for the paint to break or peel off.

Another factor that makes the team’s BaSO₄ formulation so reflective is that the researchers used Barium sulfate particles of many different sizes. When it comes to reflecting light, size matters.

Many air conditioners use hydrofluorocarbons (HFCs). While HFCs constitute just a small percentage of greenhouse gases, they trap thousands of times the amount of heat as Carbon dioxide.

Therefore, BaSO₄ can play a role in combating global warming by reducing energy consumption and the emission of HFCs.