The whitest white paint

Scientists have made the whitest of all white paints.

They did this by adding a common chemical — Barium Sulfate — to acrylic paint.

Barium sulfate or BaSO4 is a very white material that is used for many applications — two of which are worth mentioning.

Photographic papers are coated with a layer of BaSO4 (called baryta) that gives it a shiny white appearance, greatly enhancing the contrast of the image.

Patients who are about to get a CT scan are given a drink of BaSO4. The chemical goes and sticks to the intestines — making them easier to see in an X-ray or scan.

BaSO4 in other words is very reflective.

It’s this property that made researchers at Purdue University think of adding it to paint.

The new paint is 98.1 % reflective — that’s a lot. For context, heat reflective paints in the market, today usually have reflectance in the order of 80–90 %.

Because the paint hardly absorbs any heat, it remains very cool. So much so that it is 4.5 C cooler than the air around it.

Buildings of the future could therefore save a lot of money if painted with this whitest of all white paints.

From our gut to the wall, that’s quite an impressive journey.

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