Lab technicians disintegrate a pulp sample, form it on a Buchner funnel or sheet former into a disc heavy enough to be opaque, then press and dry it under controlled conditions before reading reflectance. The pad must be thick enough that its reading equals R-infinity. Pressing, drying conditions and sample handling are all fixed by the method, because each one moves the reading.
Make two brightness pads off the D2 washer and rush them, the operator wants a number before he trims the chlorine dioxide.
Also heard as
- brightness sheet
- pulp pad
Related terms
R-infinity
Reflectance factor of a pad so thick that adding more sheets no longer changes the reading.
ISO brightness
Diffuse blue reflectance factor at 457 nm, measured with d/0 geometry and UV content matched to illuminant C.
Handsheet
Laboratory-made paper sheet formed from a pulp sample under standard conditions for testing.
Brightness
The blue-light reflectance of pulp or paper, read at an effective wavelength of 457 nm and reported as a percentage.