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Barium Sulfate (BaSO4) (98.5% Purity 0.7 micron CAS:7727-43-7)
S.T.E.M. Store of Canada

Barium Sulfate (BaSO4) (98.5% Purity 0.7 micron CAS:7727-43-7)

Regular price $30.00


Note: the loonies in the small photos are just for size reference (not included).

Barium sulfate is a remarkable substance that has many applications, including:

  1. Heat-reflecting white paint. Barium sulfate is highly reflective of a broad spectrum of light, including visible light (such that it appears very white when used as a white pigment for paints), plus infrared and ultraviolet. Recently, researchers have successfully explored using it as an ingredient in paint that reflects greater than 98% of all solar radiation, thus cooling surfaces to which it has been applied (see also the YouTube video below).
  2. Radiocontrast agent. Barium sulfate in suspension is often used medically as a radiocontrast agent for X-ray imaging and other diagnostic procedures.
  3. Pyrotechnics (a niche use): barium compounds emit a characteristic green light at high temperatures.

Ours is a very fine powder, ideally suited for making heat-reflecting white paint (D50 of 0.31 μm).

We are presently offering 3 sizes: (1) a 0.6-gallon pail (~2.7 liters) that holds 2 kg of Barium Sulfate; (2) a 1.25-gallon pail (~5.7 liters) that holds 5kg of Barium Sulfate; or (3) a 500 ml bottle with a child-resistant lid that holds 375 grams of Barium Sulfate.

We are quite intrigued by its application as a heat-reflecting paint to save energy and cost, such as the following rather inspirational video:

For reference, if you'd like to make reflective paint using Barium Sulfate, we recommend starting with about 1.5 parts paint to 1 part Barium Sulfate, or 60% paint to 40% Barium Sulfate. More paint tends to yield better durability, whereas more Barium Sulfate yields better reflectivity. Here are a couple of sources for reference: Reflectance of Barium Sulfate and White Paint Mixtures (, and Ultrawhite BaSO4 Paints and Films for Remarkable Daytime Subambient Radiative Cooling | ACS Applied Materials & Interfaces.

For those interested, below are some detailed specs from our supplier:


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