The glass cuvette is an important component of the optical system in all colorimetric and turbidimetric measurements. Light reaches the sample by first passing through the cuvette glass. Based on the sample, the light is absorbed, transmitted, or scattered. As a result, the measurement can be affected if the cuvette glass has imperfections, dirt, dust, scratches, or fingerprints present.

To hide minor imperfections and scratches, the outer surface of the cuvettes should be oiled with the HI98703-58 silicone oil. The silicone oil has the same refractive index as the glass and will not alter the turbidity readings. Applying silicone oil is very important, especially for low turbidity samples (< 1 NTU), as scratches and imperfections in the glass can alter turbidity readings. Simple apply a few drops of oil onto a clean, dry cuvette and wipe thoroughly with a lint-free cloth. Wipe off the excess oil till you obtain a thin, uniform layer and the cuvette appears nearly dry, with no visible oil.