How to measure the wet hiding power of interior and exterior coatings?
The hiding power of paint is divided into dry hiding power and wet hiding power. Generally speaking, the hiding power of paint mostly refers to the latter, but the hiding power of water-soluble interior wall paint refers to the former.
Wet hiding power is usually measured by brushing.
The viscosity is specified according to the product standard (if the viscosity is too high to be painted, adjust the sample to the viscosity of the paint; but the amount of diluent should be deducted when calculating the hiding power). Weigh the total mass of the cup and paintbrush filled with the paint on a balance with a sensitivity of 0.01g. .Use a paintbrush to evenly paint the paint on the glass black and white grid board, put it in the dark box, (15~20) cm away from the frosted glass sheet, and the end with the black and white grid is inclined at an angle of 35°~40° to the plane. Observation was carried out under 1 and 2 fluorescent lamps, and the black and white grids were just invisible as the end point. Then weigh the cup and paintbrush containing the remaining paint to find the quality of the paint on the black and white grid. The paint should be applied quickly and evenly, and the paint should not be brushed on the edge of the board. Hiding power (g/m2) is calculated according to the following formula (based on wet coating film):
In the formula, W1 is the total mass of the cup and paintbrush filled with paint before painting, g;
W2 - the total mass of the cup and paintbrush containing the remaining paint after painting, g;
S—The area where the black and white grid panels are painted with paint, 000 ㎡.
Measure twice in parallel, and the difference between the results is not more than 5% of the average value, and take the average value, otherwise a new test is required.
How to measure the dry hiding power of water-soluble interior wall paint?
The dry hiding power is also measured by the brushing method.
Weigh the total mass of the cup containing the sample and the soft-bristled brush on the balance, and brush the sample on the black and white grid glass plate. The brushing should be done quickly and evenly to prevent the sample from being brushed on the edge of the broken glass plate. . Then place the painted glass plate in an electric blower box at (50±2)°C for 0.5 hours. After drying, place the glass plate in a wooden dark box, (10~20) cm away from the frosted glass sheet, and form an angle of 30°~45° between the glass plate and the horizontal plane, and observe it under the light of two 15W fluorescent lamps to obtain The layer is complete. The black and white grid shall prevail. The calculation method is the same as the wet hiding power.
