This standard specifies the two methods for determination on colour fastness of dyed papers and boards intended to come into contact with foodstuffs.
In this standard, Method A is applicable to determination on colour fastness of the dyed papers and boards (like food wrap paper) in long contact with foodstuffs (contact time ≥ 24h) while Method B is applicable to determination on colour fastness of the dyed ones (like paper napkin and kitchen paper) in short contact with foodstuffs (contact time < 24h).
2 Normative references
The following referenced documents are indispensable for the application of this document. For the dated normative references, only the dated editions are applicable to this document. For undated references, the latest edition (including any amendments) applies to this document.
GB/T 251 Textiles - Tests for colour fastness - Gray scale for assessing staining
GB/T 450 Sampling of paper and cardboard specimens and determination of vertical and horizontal, front and back of specimens
GB/T 461.1 Paper and board - Determination of capillary rise (Klemm method)
3 Principle
Contact the specimen with the glass fiber paper which has been completely soaked in the test solution for 10 min. After being placed under a certain pressure for a period of time, compare the stained glass fiber paper (the test sample) with the blank sample, and assess the grayness level with a gray scale. Choose the test solution according to the use of the paper; the test solution may be distilled water or deionized water, acid acetic dilute, simulated saliva fluid, isooctane or olive oil.
