GB/T 24999-2018 in English

GB/T 24999—2018 Standard Overview

GB/T 24999—2018, the National Standard of the People's Republic of China, was issued in 2018, replacing the old standard of 2010. The standard mainly stipulates the maximum limit of D65 brightness (whiteness) of paper and paperboard, and adds product classification and technical requirements.

Background of Standard Formulation and Analysis of Technological Evolution

D65 brightness is an important indicator for measuring the whiteness of paper, and is widely used in printing, writing and household paper. With the technological progress of the papermaking industry and changes in market demand, the original standard GB/T 24999—2010 can no longer fully meet the development needs of the industry.

The main revisions to the new standard include:

• deletion of the D65 brightness limit for inkjet printing paper due to reduced market demand for such products;
• additional brightness requirements for carbonless copy paper and light printing paper;
• adjustment of the brightness limits for products such as newsprint and writing paper.

Product Classification and Limit Requirements

Test Methods and Inspection Rules

The standard specifies two main test methods:

• Sample collection: Follow GB/T 450 to ensure that the samples are representative;
• D65 brightness measurement: Use the diffuse/vertical method specified in GB/T 7974 and measure under outdoor daylight conditions.

Implementation suggestions