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    Home > Coatings News > Paints and Coatings Market > Common knowledge of coating: common defects and treatment of wall base

    Common knowledge of coating: common defects and treatment of wall base

    • Last Update: 2020-04-03
    • Source: Internet
    • Author: User
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    Core tip: the condition of base treatment and the condition of base surface before coating construction have a great influence on coating quality and durability, so it must be taken seriously

    The following on some common grassroots

    Analysis of its possible problems, and give the corresponding measures

    (1) Unevenness of base course ① Possible problems A

    thin coating or uneven coating due to base water absorption; B

    increase the amount of putty

    ② Treatment measures before applying putty, the base course shall be made of materials similar to the base course Paint knowledge how about Akzo Nobel Powder Coating Recommended introduction: powder coating is a kind of coating with different form from general coating, which is in powder form

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    Since the introduction of this technology, powder coating has been able to continue to maintain the Coating home news: the base treatment and the surface condition of the base before the coating construction have a great impact on the coating quality and durability of the coating, which must be taken seriously

    The following on some common grassroots

    Analysis of its possible problems, and give the corresponding measures

    (1) The problems that may arise from the unevenness of the base ①

    A

    the thin coating or the uneven coating due to the water absorption of the base; B

    increase the amount of putty

    ② Before applying putty, the base course shall be further leveled with materials similar to the base course

    (2) Surface laitance, grease, etc

    ① problems may occur in the base course, such as pulverization, whitening, laitance skin, dust, grease, isolating agent, cement slurry and mortar leaked during concrete pouring, ash picking mortar and other attachments, which will affect the adhesion strength of the coating

    ② The treatment measures must be based on the specific situation, take corresponding measures to remove these surface defects (such as thorough removal or wire brush removal, etc.) and then carry out base treatment

    In the process of chiseling and cleaning or scraping, if there is local depression and small flat, carry out base treatment to make the surface flat

    (3) The surface loose layer ① may cause problems that affect the adhesion strength of putty or coating, and in serious cases, it may cause the coating (putty) film to fall off

    (2) after treatment, the polymer emulsion cement putty can be scraped and smoothed and polished once or repeatedly (depending on the thickness)

    (4) The separation layer of cement mortar that should not be removed ① may cause problems after coating, because the change of temperature and / or humidity may further aggravate the separation layer, or even cause falling off in serious cases, leading to coating engineering failure

    ② treatment measures Drill a hole with a diameter of about 5mm with an electric drill, and inject the epoxy resin adhesive or polymer cement slurry into the separation layer gap to make it bond firmly

    The adhesive strength of epoxy resin is high, but it is solvent type, construction is not easy to operate, and the cost is high; the early age strength of polymer cement slurry is low, but it is water-based, easy to operate, and the cost is low

    (5) The surface strength of the base course is low ① the surface strength of the aerated concrete board and calcium silicate board may be low, which will cause the coating to peel off due to the condensation damage of the surface

    ② Treatment measures for aerated concrete slab, calcium silicate slab, etc., the interface treatment agent of aerated concrete can be used for surface treatment, or the sealer can be diluted by twice with water, and then two coats can be painted on the base course surface; for the cast-in-place concrete surface with poor curing, the vulnerable part shall be removed to make the surface flat, and then the polymer cement mortar or putty shall be used to repair the surface flat

    (6) Problems of poor surface solidification of cast-in-place concrete ① in this case, the surface strength of the base course is low, and the coating will also peel off due to the condensation damage of the surface

    ② According to the specific situation of poor curing, the treatment measures are the same as "low surface strength of base course"

    (7) Problems such as sanding and pulverization of the old concrete outer wall ① may cause the new coating to fall off and bulge soon after coating, especially when the coating is damaged by water in rainy days after coating

    ② Treatment measures: for the case of sanding, cement-based materials can be used for finishing; for the case of surface pulverization, wire brush can be used for cleaning, and in case of not serious situation, diluted sealing agent can be used for brushing or aerated concrete interface agent can be used for treatment

    (8) Mould spots on the old concrete wall ① may cause problems

    If there are green or black mould spots on the old wall, the uniformity of the coating color will be damaged after coating

    Even further corrosion of the new coating

    ② After the mildew is removed, the thin magnesium fluosilicate or bleaching powder solution or 7% - 10% trisodium phosphate aqueous solution is used for cleaning and sterilization, and the coating is applied after drying

    (9) Cracks in base course, honeycomb and other defects ① may cause cracks in putty layer and lead to cracks in coating

    (2) the surface cracks of the treatment measures should be filled with cracks or elastic putty, then the polymer emulsion cement putty or the same material as the base material should be patched, smoothed and polished

    The deeper cracks should be cut into V shape and filled with waterproof

    The material is then smoothed and polished with polymer emulsion cement putty

    For honeycombs, polymer emulsion cement putty or polymer emulsion cement mortar is used to repair the surface

    If the crack is caused by drying shrinkage, because it will take a long time to stabilize, it can be treated according to the specific situation of various base courses

    (10) The problems that may occur in the holes and holes of the base layer may affect the application of putty and coating

    The quality of coating film and putty film may be deteriorated due to the change of temperature and humidity

    2

    The holes and holes with diameter greater than 3mm should be filled with polymer emulsion cement mortar, and small holes can be filled with polymer emulsion cement putty, and the surface is polished and leveled

    (11) The possible problems of surface unevenness and pockmarks may cause a large amount of putty due to the need of surface flatness, which may cause the quality feedback problem of putty film or coating film, or the quality problem of coating film after coating

    (2) the treatment measures should be sandpaper or wheel grinding or shovel clearance or chisel; concave and pitting are serious, and can be scraped and polished by polymer emulsion cement putty or polymer emulsion cement mortar

    (12) The hollowing and damage of mortar, plaster and other plastering bases ① the hollowing part may fall off after coating or the coating film may be damaged due to the aggravation of damage

    (2) if the treatment measures are not serious, the polymer cement slurry can be injected into the hollow drum (for example, using styrene acrylic emulsion and ordinary portland cement); if the drum condition is serious, the hollowing and damage parts should be thoroughly cut out, and the surface should be repaired with the same material as the base

    (13) If the base course is wet, the putty film or film may dry, shrink, crack, fall off, etc.; for cement base course, it may cause coating peeling, blistering, etc

    ② The treatment measures must take the moisture content of the base course and the apparent alkaline matter into consideration

    After the base course is dry and the pfvalue of the base course drops to below 9, the construction can be started again

    Although pH may decrease naturally with age, it may take a long time

    If the construction period is tight, measures can be taken to reduce it

    For example, brush the base course with 5% - 10% dilute hydrochloric acid and then wash it with water; or brush the surface with 15% - 20% zinc sulfate or zinc chloride solution or sulfamic acid solution several times

    Remove the precipitated powder and floating particles after drying

    (14) High base alkalinity: ① problems that may occur after the coating construction, the water evaporated from the concrete surface dissolves the basic components of the base, which may affect the coating film; for the coating with poor alkali resistance, it may lead to peeling and blistering of the coating film; for the coating with dark color, the alkaline substances remain on the surface of the coating film, forming "white frost" (also known as "Pan alkali") O ② treatment measures According to the specific situation, take the same measures as "base damp"

    (15) Problems that may occur to the bare iron parts of the base course ① the metal iron parts on the surface of the prefabricated plate base course and the wood screws and nails used for the installation of the plate will rust after the coating, and the rust will affect the coating, pollute or cause peeling off of the coating

    The nails for installing indoor walls and ceiling plates are often rusted and polluted due to the damage of zinc coating on nail cap caused by hammering

    ② Treatment measures before coating construction, rust prevention or sealing measures shall be taken for iron parts, such as coating the surface of iron parts with solvent varnish

    (16) The surface flatness of coating engineering is affected by the possible problems of formwork dislocation edge ①

    ② The treatment measures are to use the portable electric grinder to polish and level the concave

    (17) The possible problems of plate joint ① will expand after coating, which will cause large cracks on the coating surface

    ⑦ The treatment measures are different according to the types of plates

    For example, for the joint of plywood, the adhesive with high bonding strength and the fiber fabric (cloth) paste are used for reinforcement; for the joint of gypsum board, the joint is chiseled into a V-shaped groove, then the special gypsum mortar is used for filling several times, and the adhesive with high bonding strength and the fiber fabric (cloth) paste are used for reinforcement

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