Wet film thickness measurements are generally used by applicators as a guide to determine the prescribed amount of paint that needs to be applied to obtain the desired dry film thickness. There are generally two types of wet Film Thickness Gauges: wet film thickness wheel gauge and wet film thickness comb gauge. For the detection method and technique of wet film thickness, see the relevant content later.
The advantage of using a wet Film Thickness Gauge is that improper . If the applicator knows the wet film thickness, when this data is multiplied by the volume percentage of coating solids, the dry film thickness can be estimated
Dry film thickness (pm) = wet film thickness (μm) × coating solid content (volume percentage)
Actual amount of paint (kg) = (1+a) X theoretical coating amount of paint (kg/m2) X coating area (m2)
In the formula, a is the paint consumption coefficient
In actual construction, due to the unevenness of the surface of the object to be coated, the influence of wind speed in the consumption environment during the coating process, and the different types of construction tools, the coating will inevitably have different degrees of loss. The value of a is not a constant. It is determined by various factors are determined comprehensively. Generally, the a value of high-pressure airless spraying flat surface is 0.6~0.8; the value of a value of complex surface spraying is C 1.0; the value of a value of manual painting flat surface is 0.3~ 0.4;
Coating operators can use the wet Film Thickness Gauge to check and apply while adjusting the wet thickness at any time. During construction, the detection frequency of wet film thickness can be arbitrary. When spraying a large and flat surface and the operation is skilled, the detection frequency can be less. In the case of complex and unskilled operation, the detection frequency can be higher. It is generally required to distribute the measurement points evenly on every 10m2 coating surface. Generally, 5 measurement points are distributed in 1m2, each measurement is three times, and the average value is measured to improve the reliability of the wet film thickness. In architectural coatings, the surface of reinforced concrete, not Where destructive testing is not permitted, wet film thickness determination may be used instead of dry film thickness determination.
In most cases, the measurement of wet film thickness is only an auxiliary means to ensure the dry film thickness. For inorganic high-zinc coatings and some fast-volatile coatings, the ratio of dry film/wet film varies greatly and only the wet film thickness is used to estimate the dry film. Thickness, may bring wrong results, the evaluation of the total film thickness should also be based on the dry film thickness.
