Paper labs calibrate against standards traceable to the perfect reflecting diffuser: opal glass, ceramic or pressed-powder references for the white scale, and fluorescent paper standards for UV adjustment. The values come from an authorized laboratory and carry an expiry, because paper and fluorescent standards age. An out-of-date standard shifts every brightness and whiteness value the lab reports by the same error.
New IR3 reference standards came in, so retire the old set and log the switch in the instrument book.
Also heard as
- calibration standard
- certified standard
Related terms
Cal tile
Lab shorthand for the white or colored ceramic tile used to check or standardize an instrument each shift.
UV calibration
Setting an instrument's ultraviolet content so fluorescent samples read as they would under the specified illuminant.
Reflectance factor
How much light a sample sends back compared with an ideal white diffuser lit and viewed the same way.
Spectrophotometer
Instrument that measures reflectance across the visible spectrum and computes brightness, whiteness, opacity and color.