The method and apparatus for on-line measuring the coating weight on art paper are described. The design of the coating gauge was based on the technique of characteristic X-ray fluorescence preferential absorption. The gauge was equipped with a TP-801 micro-computer which makes the gauge capable of showing and typing the data in different forms. The measurement is quick

continuous

accurate and non destructive. Analysis period is 10 seconds. In on line measuring

the reproducibility is ±1g/m

2

and the relative error of this method amounts to ±5% with the weighing method as a standard.