Anti-glare performance testing of exercise books evaluates the optical characteristics of workbook paper, including specular gloss, brightness, and whiteness, that determine how much reflected light reaches a student's eyes during reading and writing. Testing is performed in accordance with recognized methods such as GB 21027, ISO 8254, ISO 2470, and ASTM D523 to verify compliance with mandatory safety requirements and eye-protection specifications. This article outlines the technical principles, sample requirements, test items, measurement procedures, and typical applications of anti-glare evaluation for exercise books and related school paper products.
Technical Overview
Glare on an exercise book page originates from two optical phenomena: specular reflection, in which lamps, sunlight, or windows form mirror-like highlights on the paper surface, and excessive diffuse luminance, in which an overly white or bright sheet reflects a large proportion of incident light toward the eye. Because students typically read and write at close range for extended periods under classroom lighting, both effects increase visual fatigue and are treated as safety-relevant characteristics of school supplies.
Anti-glare performance is therefore controlled by limiting the specular gloss and the brightness (whiteness) of the paper. In China, the mandatory standard GB 21027-2020, General Safety Requirements for School Supplies, restricts the whiteness of paper used for exercise books to no more than 85%, directly addressing glare and visual comfort. Supporting measurement standards include ISO 8254 (specular gloss of paper and board, also implemented nationally as GB/T 8941), ISO 2470-1 (ISO brightness, implemented as GB/T 7974), ISO 11475 and ISO 11476 (CIE whiteness), and ASTM D523 (general specular gloss measurement). Accredited third-party laboratories apply these methods to generate objective, reproducible data on the glare potential of exercise book paper.
Testing Samples
Inner Page Paper (Writing Sheets)
The primary test specimen is the uncoated writing paper used for the ruled inner pages of the exercise book. Because the two sides of a sheet, the wire side and the felt side, can differ in smoothness and gloss, both sides are identified and evaluated separately. Ruled lines and printed marks influence reflection, so gloss and brightness measurements are taken on unprinted regions of the page wherever possible.
Covers, Coated Boards, and Coated Papers
Covers made of coated board, varnished printed stock, or laminated materials exhibit significantly higher gloss than inner pages and are treated as a distinct sample type. Where a product line includes coated inner pages, such as notebooks produced with art paper, those sheets are also submitted and evaluated separately.
Sample Preparation and Conditioning
Sampling is carried out in accordance with ISO 186 (GB/T 450) so that specimens represent the average quality of the production lot. Sheets must be free of folds, creases, fingerprints, and surface contamination. Prior to measurement, specimens are conditioned in the standard atmosphere of 23 °C and 50% relative humidity in accordance with ISO 187 (GB/T 10739) until moisture equilibrium is reached, typically requiring at least 24 hours. A minimum of ten sheets per sample type is customary to ensure statistical validity.
Testing Items
A typical anti-glare evaluation of an exercise book comprises the following items:
- Specular gloss at 75° for low-gloss uncoated writing paper, with 60° and 20° geometries for coated or high-gloss components
- ISO brightness, expressed as the diffuse blue reflectance factor (R457), determined per ISO 2470-1
- CIE whiteness determined per ISO 11475 (D65/10°) or ISO 11476 (C/2°)
- Compliance verification of measured whiteness against the 85% maximum limit specified in GB 21027-2020
- Reflectance uniformity across the sheet, including gloss variation, brightness variation, and mottling
- Optional CIELAB color and reflectance factor measurement per ISO 5631 to document the overall optical appearance of the page
Testing Methods
Specular Gloss Measurement
Gloss is measured with a calibrated glossmeter using a geometry appropriate to the surface. Uncoated exercise book paper, a low-gloss diffuse surface, is measured at 75° in accordance with ISO 8254-1 (GB/T 8941); coated covers may be measured at 60° or 20° per ISO 8254-3 or ASTM D523, and JIS Z 8741 is referenced for equivalent requirements in the Japanese market. The instrument is verified against certified polished black glass references and working standards traceable to national metrology institutes. Each specimen is supported on a rigid flat backing plate, and at least ten readings are taken at distributed positions on unprinted areas of each side. The laboratory reports the mean, maximum, and minimum gloss values; lower and more uniform gloss indicates reduced glare potential.
Brightness and Whiteness Determination
ISO brightness (R457) is determined with a reflectance photometer equipped with the prescribed blue filter under illuminant C conditions, following ISO 2470-1 (GB/T 7974). Specimens are cut and stacked into an opaque pad, and the reflectance factor is measured on both faces, with the average of at least ten determinations reported. CIE whiteness is calculated from full-spectrum reflectance data acquired with a spectrophotometer per ISO 11475 or ISO 11476, producing a single value that quantifies the overall luminous appearance of the sheet. Results are compared directly with the 85% whiteness ceiling required for exercise book paper by GB 21027-2020.
Uniformity and Visual Assessment
Reflectance uniformity is evaluated by mapping gloss and brightness readings across the sheet and calculating positional variability. A supplementary visual examination under standardized D65 illumination at representative reading angles confirms that no localized glare spots, gloss streaks, or mottled reflection patterns are present. This combined instrumental and visual approach ensures that satisfactory average values do not mask localized glare defects on the finished page.
Applications
Anti-glare test data serve multiple stakeholders across the school supply value chain:
- Regulatory compliance: manufacturers and importers demonstrate conformity with the mandatory whiteness requirement of GB 21027-2020 before placing exercise books on the market
- Quality control: paper mills and notebook converters monitor gloss and brightness during production and adjust refining, filler content, sizing, calendering, and coating parameters to keep glare low
- Product claims: brands use reports from accredited third-party laboratories to substantiate eye-protection and low-glare marketing statements
- Institutional procurement: schools, educational authorities, and retail buyers reference test results in supplier qualification and tender specifications
- Research and development: laboratories support the optimization of low-gloss surface treatments and alternative paper furnishes for next-generation eye-care stationery
FAQ
What is anti-glare performance, and why does it matter for exercise books? Anti-glare performance describes how effectively the paper surface suppresses mirror-like reflections and excessive brightness under classroom lighting. Because students concentrate on workbook pages for hours at close range, limiting glare reduces visual fatigue and supports long-term eye health.
Which standards govern the testing? The mandatory requirement is GB 21027-2020, which limits exercise book paper whiteness to 85%. Measurement methods include ISO 8254 (GB/T 8941) for specular gloss, ISO 2470-1 (GB/T 7974) for ISO brightness, ISO 11475 and ISO 11476 for CIE whiteness, and ASTM D523 or JIS Z 8741 for complementary gloss geometries.
Why is 75° the preferred gloss angle for inner pages? Uncoated writing paper is a low-gloss, diffusely reflecting surface. The 75° geometry defined in ISO 8254-1 provides the sensitivity and reproducibility appropriate for such surfaces, whereas 60° and 20° geometries are better suited to medium- and high-gloss coated materials.
How many samples are required, and how should they be submitted? A representative lot sample of at least ten full sheets per paper type is customary, submitted flat, clean, and clearly identified by paper side. The laboratory conditions the specimens at 23 °C and 50% relative humidity before measurement.
What does the test report include? Reports typically present mean, maximum, and minimum 75° gloss values, ISO brightness, CIE whiteness, a compliance statement against the GB 21027-2020 whiteness limit, and documentation of any localized glare nonuniformity, issued by accredited third-party laboratories.