Technidyne Header Image

Monday, May 13, 2013

Why a Barium Coated Sphere is BAD Technology

Barium sulfate has been used to coat spheres used for diffuse brightness measurement ever since the development of the Zeiss Elrepho in the early 1960's in Germany.  It was used because it was more stable than Magnesium Oxide (less yellowing) and had relatively constant high reflectance (approximately 95%) from 400 nm to over 1200 nm.

In the mid-1990's, many different companies started producing more advanced, high-white coatings.  Technidyne chose to start using Labsphere Spectraflect.  It has the nice, high reflectance of barium sulfate in the visible spectrum (98-96%) and beyond.  It is also far more stable over time.  Barium sulfate spheres even in a protected environment with constant temperature and humidity will yellow over time far faster.

Technidyne has not used barium sulfate to coat its spheres for close to 20 years for instruments like the Color Touch.  Datacolor and some other manufacturers still use this inferior coating for its spheres. This results in greater deterioration over time than modern sphere coatings. A degraded sphere will absorb more light, especially in the UV, violet and blue part of the spectrum.  This will make instruments either impossible to calibrate or require more frequent changing of light sources to provide enough UV to overcome the absorption caused by the sphere.  This can also make it more difficult to get inter-instrument agreement over a variety of devices of different vintages.  Finally, barium sulfate spheres are far more susceptible to moisture effects. This can be seen when measuring wet handsheets. The moisture will be absorbed into the coating and make a 'ring' around the aperture, therefore, effecting the spheres efficiency.

Technidyne makes sure you are using the best technology available. This makes your device, calibration and laboratory operate at its highest efficiency.

What technology should Technidyne employ in its products/services?

What technology do we currently use that you especially enjoy?