Pro Lite Technology

Barium Sulphate Coating


Pro-Lite's range of barium sulphate (BaSO4) coatings are scientific-grade paints that exhibit near-perfect diffuse reflectance at levels up to 98% in the 250-2500nm (UV-VIS-NIR) wavelength range. Available as an affordable water-based formulation or as an ethanol solution or ethanol pre-mix, barium sulphate is used to coat integrating spheres, lamp housings, backlight reflectors and laser pumping chambers, in fact anywhere where you need efficient, uniform illumination.

Commonly referred to as "integrating sphere paint", our barium sulphate coatings can be used on almost any substrate material (glass, plastics, metal, wood) and are best applied by spray painting (airless spray gun). Spray painting allows you to layer the paint gradually - at 12-15 layers, you achieve the optimum thickness and maximum reflectance. Brush painting is possible to touch up small chips on an already painted integrating sphere for example, but brush painting from scratch will not yield good results. At the optimum coating thickness of about 0.5 to 0.6mm, 1 litre of barium sulphate paint will cover an area of approxmately 0.25m2.

Our affordable water-based formulation provides good optical performance and avoids the added costs associated with alcohol-based paints (hazardous cargo restrictions and costs apply to those) but the water-based formulation does take longer to apply. Reckon on between 5-6 hours total including drying time between layers assuming a warm, dry environment and some forced air drying of the paint. The ethanol-based paints are more expensive to transport (there are also storage restrictions) but the solvent evaporates more quickly which reduces the overall coating time.

The water-based barium sulphate paint is available in standard volumes of 0.5, 1.0 and 5.0 litres and in value packs of 2 x 1.0 litre bottles, 3 x 1.0 litres, 5 x 1.0 litres and 2 x 5.0 litres.

The ethanol-based formulation is available in 250, 500 and 1000ml volumes and as a 250ml bottle of pre-mix which requires an equal volume of spectroscopic-grade ethanol to dissolve it in. Because ethanol is flammible, special hazardous cargo restrictions apply to these paints, as do local storage requirements (excepting the pre-mix, this is not flammible). Because of this, the ethanol-based paints are much more expensive but the alcohol evaporates more quickly than water and the drying time between layers is much reduced. This helps to keep the overall time to coat a reflector to a minimum.

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