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Views: 0 Author: Site Editor Publish Time: 2026-11-12 Origin: Site
Tissue paper brightness is the percentage of blue light the sheet reflects at an effective wavelength of 457 nm, measured under the ISO 12625-7 optical method with a D65 illuminant and 10° observer. It is a diffuse blue reflectance factor, defined by ISO 2470 and ISO 2469, and is read to a precision of 0.05%. Brightness is not the same as whiteness: brightness uses a single blue wavelength, while CIE whiteness scores the whole visible spectrum, and opacity (ISO 12625-16) measures how much the paper blocks show-through.
Brightness quantifies how white a sheet appears on a blue-white scale. The instrument directs light at an effective wavelength of 457 nm with a half-bandwidth of about 44 nm, then measures the diffuse reflectance relative to a calibrated standard. The result is expressed as a percentage, typically reported to 0.05%.
Because the measurement sits in the blue region, it is sensitive to yellowing and to residual lignin or colour. A higher number means a bluer, brighter sheet; a lower number means a warmer, more natural tone.
Conditioning: samples are equilibrated at 23 °C and 50% RH (ISO 187).
Instrument geometry: a spectrophotometer/colorimeter follows the diffuse/0° geometry of ISO 2469.
Illuminant and observer: colour and whiteness use D65 daylight with the 10° standard observer under ISO 12625-7.
Blue reflectance: the 457 nm brightness value is calculated per ISO 2470.
Calibration: the instrument is set against certified standards, and readings are reported to 0.05%.
These three optical terms are often confused but measure different things.
Property | What it measures | Standard | Basis |
|---|---|---|---|
Brightness (ISO) | Blue reflectance at 457 nm | ISO 12625-7 / ISO 2470 | Single blue wavelength, % |
CIE whiteness | Whiteness across the visible spectrum | ISO 12625-7 / ISO 11475 | Full-spectrum D65, 10° |
Colour (Lab*) | Lightness and colour cast | ISO 12625-7 | CIE Lab* under D65 |
Opacity | Resistance to show-through | ISO 12625-16 | Diffuse reflectance over a paper backing |
CIE whiteness evaluates the entire visible range rather than one blue band, so it better matches how people perceive a "white" product. It can distinguish a neutral white from a blue-tinted or green-tinted white that may share a similar brightness number.
Opacity is the ratio of diffuse reflectance over a black backing to that over a white paper backing, expressed as a percentage. It tells you whether printing or the underlying ply shows through. The 2024 edition of ISO 12625-16 defines the paper-backing, diffuse-reflectance method for tissue. Higher opacity matters for printed napkins and multi-ply products.
Pulp type: bleached virgin kraft pulp reaches high brightness; unbleached or recycled fibre is generally lower and more variable.
Bleaching and optical brightening agents (OBAs): OBAs absorb UV and emit blue light, raising measured brightness and whiteness.
Water and process cleanliness: contamination or residual colour lowers the reading.
Ageing and storage: heat, light and moisture can cause yellowing over time.
Fibre choice: short hardwood fibres improve formation and evenness, supporting uniform optical readings.
A natural, low-OBA sheet is deliberately not maximised for brightness and is preferred for some premium and sensitive-skin lines. Brightness is therefore a target to specify, not a value to push as high as possible.
HUAXIN measures optical properties under ISO 12625-7 and opacity under ISO 12625-16, alongside grammage (Part 6), thickness (Part 3), tensile (Parts 4/5) and absorption (Part 8). Reels span width 200–2850 mm, GSM 11–42 g/m², diameter up to 1150 mm and a 76 mm (3 in) core, with moisture at 4–7%. A full container holds about 26 reels / 12–13 tons.
What is the standard for tissue paper brightness? Brightness is measured under ISO 12625-7, referencing ISO 2470 and ISO 2469. It is the diffuse blue reflectance factor at an effective wavelength of 457 nm, reported to 0.05%, with colour and whiteness evaluated under D65 and the 10° observer.
Is brightness the same as whiteness? No. Brightness measures reflectance at a single 457 nm blue wavelength, while CIE whiteness evaluates the full visible spectrum. Two sheets can have similar brightness but look different in overall whiteness or tint.
What is tissue opacity and which standard covers it? Opacity measures how much the paper resists show-through, using diffuse reflectance over a paper backing. It is covered by ISO 12625-16 (2024 edition) and is important for printed and multi-ply tissue.
Do optical brightening agents increase brightness? Yes. OBAs absorb ultraviolet light and emit blue light, raising measured brightness and CIE whiteness. Natural, low-OBA products are specified at lower brightness for a softer, less artificial look.
