In 2023 CISP started a non-evaluative collaborative study to verify the repeatability and reproducibility of a new UNI standard proposal for the determination of enamel resistance to corrosion and hot water. The purpose of the research is to support the implementation of a robust methodology that can be used to fairly assess both wet and powder technology by mirroring real usage. The purpose of the research is also to train multiple labs in Europe to use this methodology and be ready to perform it.
As to the methods employed in the study, CISP selected 11 laboratories in Europe (company labs, third party labs and academic labs). Labs were asked to perform tests on 3 samples for a maximum of 3 sessions. Samples were exposed to hot water attack (grade 2) to determine mass loss per unit area (grams/square meters) of the product (inside of the tank). The test period consisted of two cycles, the first cycle of 48 h (2 d) and the other of 840 h (35 d), considering the average value of the mass loss of the second cycle. Samples plates’ thickness ranged from 250 to 280 μ, with enamel manual application and industrial firing. Estimates of precision were obtained using the procedure in ISO 5725-2:2019 Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method - Clause 8: Statistical analysis of a precision experiment. Mandel's k and Cochran's tests were used to examine within-laboratory consistency, while Mandel's h and Grubbs' tests were used to examine between-laboratory consistency.
?Results have shown repeatability and reproducibility standard deviations are satisfactory.
The Interlaboratory study proved UNI’s methodology is robust and can be taken as a reference both by industry and market surveillance authorities.