Latex paint construction quality disadvantages and solutions

Latex paint as a major variety of architectural coatings, is widely accepted, but there are also skin cracking, floating hair flowers, powder fading, coating surface rough, poor cover, color incogenity and other defects, these defects are mainly reflected in the grass-roots materials, coating process, latex paint quality, construction environment and so on.
Prominance maladies
First, floating color, flowering, frosting, uneven color
(1) before construction, the paint stirring is not uniform, excessive water or water methods do not meet the requirements, resulting in paint pigment flocculation or stratified dissosis appear floating color.
(2) the surface of the grass is rough and uneven, when applied concave parts of the paint more, convex parts of the paint is less, the coating thickness is uneven, the color of different shades and flowers .
(3) The new wall is not dry, the outside is wet, especially the north facade or ±0.000 to -0.450 m of the base site is in a long-term wet state and scaffolding eyes or construction of reserved holes after repair is not dry, the wall of lye and water-soluble salts, with evaporation of water and seepage, with the air carbon dioxide to produce carbon dioxide white crystals, This causes the coating to flower, frost, and even peel off.
(4) when applied, do not use alkali-resistant closed primer, uneven brushing, leakage brush serious, resulting in the production of alkaline substances, resulting in the coating surface frost, whitening, flowering.
(5) applying the wall is too dry, the coating on the paint absorption capacity is too strong, when the tweezers or brushes just touch the wall, local paint is absorbed more, less absorption in the rolling brush, resulting in uneven coating thickness, paint film drying after the entire construction surface color is uneven, inconsistent, there are obvious brush marks at the joint., finish layer powdering, cracking, peeling or peeling
(1) grass moisture, moisture content of more than 10%, coating too thick, dry table. There are alkaline substances in the wall, pH value is greater than 10, not rinsed with water or not used weak acid water and treatment, after application of the grass-roots closure, water vapor seepage is not smooth, so that the grass-roots alkaline, salt seepage, resulting in coating film and grass-roots loss of adhesion and cracking.
(2) putty bonding strength is low, flexibility is not enough, crack resistance is poor. Good scratching, poor plasticity, water absorption after volume expansion soft, dry after peeling, powdering, water immersion to produce an unearral size of circular bubbles, the surface coating film top up, lose binding force, so that shading cracking off or the whole piece peel off.
(3) the construction temperature is low or the ambient humidity is greater than 75%, resulting in poor film quality and cracking.
(4) the grass-roots treatment is not proper, the surface has loose, dust, oil, rust and other unclean things. The auxiliary materials used are of poor quality, have low bonding strength, and are prone to dust forming an isolation film, resulting in foaming, peeling and peeling of the coating.
(5) Paint film quality is poor. Pigment, filler content is too high, the content of the base material is too small, adhesion is poor, the coating can not continue to form a film and crack, when water falls off., the construction process appeared flow hanging, flowing
(1) before application, the paint stirring is not uniform, too much water, did not control the paint construction viscosity.
(2) coating is applied thick (more than 20 to 25 m coating thickness), and the flow or flow is directly related to the thickness of the coating film.
(3) the construction environment temperature is low or humidity is too large, the coating is slow to dry, in the film flow is large.
(4) the coating sequence or coating method is incorrect, and unskilled skills can result in in inconsistent flow, flow, or color.
(5) the water content of the grass is too large or the grass is too smooth, resulting in poor adhesion of the paint film.
Solutions
First, grass-roots treatment
(1) Grass-roots surface must be solid, flat, smooth, dry, clean, oil-free, no large cracks; The bulging drum pack should be removed, the bump applied with the same composition as the surface polymer putty or glue patching, flattening, and full maintenance, maintenance period at room temperature: the concrete wall is 28 d, the new gray wall is 14 d.
(2) Check the flatness of the wall, the grass-roots missing corners, uneven places with polymer mortar repair and smoothing, hemp surface and cracks with flexible putty to fill the flat, the grass surface of dust, dirt, splashes, mortar and flow marks should be cleaned up.
(3) Wall frost with 5 to 10 sour water solution to treat once, 24 h and then use clean water to rinse the wall from top to bottom 2 to 3 times, to keep dry more than 3 d, until the water content of the wall is less than 10%, can be applied.
(4) The old wall renovation should first remove the floating dust, remove sand, skin, oily parts, should be removed from the original coating, can not be eliminated to be cleaned with detergent.
(5) the exterior wall generally scrapes putty two, The putty used must have a certain strength, flexibility and water resistance, and the grass-roots bonding is solid, batch scraping must not appear powder, skin, cracks; The second putty should pay attention to find a flat surface, batch scraping thickness of less than 0.5 mm, after drying with 100 or 120 sandpaper sandpaper smooth, scratch-free, and clean the surface dust.
II, coating construction
(1) before coating, should carefully read the product description, control the water content of the grass-roots less than 10%, pH is less than 9.5;
(2) when applying, the grass should first brush an anti-alkali closed primer, the purpose is to effectively prevent water solution from the grass roots, promote uniform absorption of paint, improve the adhesion of the paint and coating durability, at the same time can also save 10% to 30% of the paint.
(3) Before construction, the coating should be fully stirred, so that it is uniform, no floating color or precipitation;
(4) when using light or dark paints on the exterior walls, priority should be given to the color of pigments with good weather resistance, such as iron oxide series or indistinct series.
(5) Application operation should be in accordance with the "four fixed" principle, that is, fixed area, fixed dosing, fixed construction section surface, fixed brush direction;
(6) When painting a large area of the outer wall, the boundary shall be divided by the gap seam, the yin and yang corner of the wall or the water drop pipe, and the same wall shall be coated with the same batch, each coating shall not be too thick, and the interval shall not be less than 2 h. Each brush should be applied in one direction and the next time it is painted, it should be in the other direction. Make sure that the brush is uniform, the upper and lower joints are unmarked, the color is consistent, the demarcation line is clear and neat, straight.
(7) Exterior wall coating construction, must always understand and master the weather forecast, to prevent the coating film before drying by rain, strong air flow and high dust pollution.