The exterior wall latex paint is in accordance with the national standard GB / t9755-2001, which is divided into qualified products, first-class products and excellent products (see the attached table), but the most important indicators (product differences of different manufacturers) are:
1. Aging resistance;
2. Washability and water resistance;
3. Contrast ratio (i.e. covering power).
Of course, users would like to use a simple method to distinguish the advantages and disadvantages of exterior wall emulsion paint:
(1) aging resistance
Put two pieces of glass or ceramic tiles side by side, brush different paints (a, B, c) on the top, wait for 1 hour to dry, put one piece of glass in an oven at 200oC for 2 hours, and then take it out for cooling to compare the yellowing condition. Serious yellowing indicates poor quality and aging resistance. The advantages and disadvantages of solar radiation resistance are generally:
① the anti yellowing effect of silicon acrylic and pure acrylic is better than that of styrene acrylic paint, and that of styrene acrylic paint is better than that of vinegar acrylic paint and common paint.
② there will be some differences in yellowing of styrene acrylic paint from different manufacturers, which is the difference in formulation technology.
(2) washability and water resistance
① from the outside of the brush sample: the washability of the glossy paint is greater than that of the matte paint, so the high-grade exterior wall paint is generally semi matte (or eggshell light), (the glossy paint can not be widely used due to its high reflection, high requirements for construction flatness and aesthetic reasons). The washability of varnish is generally more than 2000 times, some even more than 20000 times. So it's hard to compare the difference between high gloss paints with brush.
② comparison of water resistance of glossy or semi matte paint: paint film can be brushed (evenly applied) on the glass, after drying, it can be immersed in water for comparison, and the degree of blistering, peeling and falling off can be observed. The more bubbles, the faster the water resistance.
③ it is also two kinds of matte paint, and the difference of water resistance can also be distinguished:
A. spray two kinds of paint film with clear water, the one without change is better; the one with wet hair and dark hair is worse, which is medium and low grade paint; the one with soft and damp skin is the worst, which may be unqualified.
B use nails to carve two kinds of dry paint film. The hard quality is good, the resin binder is more, and the water resistance is excellent; the soft one is poor, and the cost is low.
(3) contrast ratio
Dip in a little two kinds of contrast paint and cover the newspaper with the same thickness to see which paint is easier to cover the black words. Wet paint film is easy to cover the contrast ratio of black words is high, there are many white pigments in the formula, which is high-grade paint; on the contrary, it is low-grade paint. If the wet paint is difficult to cover the black words, but it can cover after drying, it indicates that the type of paint is low-grade.
Of course, in addition, users can easily test the solid content of 1 jin of paint. Paint of the same grade (such as semi gloss), the higher the solid content, the better, that is, the less water, the better. The solid content of excellent exterior wall paint is between 50-60%.