Surface Encyclopedia: Metal and non-metal surface coating cleaning method
Surface Encyclopedia: Metal and non-metal surface coating cleaning method
2018-04-13 10:00:44
Different metals have their own best surface treatment methods, depending on the hardness of the metal.
1, steel
The most effective way to clean uncoated steel is to use solvent cleaning or steam cleaning after sandblasting. In fact, the SSPC standard requires solvent cleaning before manual and power tool cleaning and sandblasting. Sand blasting is recommended for cleaning of damaged areas. Water jetting and water blasting are also good options, especially in areas where dry blasting is not acceptable. Other methods, such as manual or power tool cleaning, are more suitable for small-scale maintenance.
2, galvanized steel
Due to the different surface conditions, the recommended cleaning methods for unpainted galvanized steels vary. Simple solvent cleaning of new clean galvanized sheets is sufficient to remove any protective oil used for outdoor storage of galvanized sheets. Other temporary protective measures such as chromate treatment must be removed using the manufacturer's recommended method. Epoxy and latex coatings have no roughness requirements and can be tightly bonded to the surface of a smooth, clean galvanized sheet, but some constructors believe it necessary to use phosphoric acid or other chemical treatments.
3, aluminum and other soft metals
New and clean aluminum and other soft metals can be cleaned thoroughly with solvent cleaning. Dust and loose corrosives can be removed with cleaners; old paint can be removed with plastic particles or other light blasting methods and sand blasting with coarse particles (steel balls or shots) can damage the soft metal surface. These metal surfaces can be cleaned first to increase adhesion to oily or latex paints.
4, alloy steel
Low-alloy steels generally do not need to be protected by painting but rely on the natural oxide film formed. If it is necessary to remove inconspicuous rust spots for painting, high pressure or ultra-high pressure water spraying is required. In order to achieve surface roughness, it is also required to increase sandblasting particles. A coating system usually used for steel structures is generally used.
The purpose of stainless steel coating is for a satisfactory appearance. In order for the primer to adhere tightly to stainless steel or other hard metals, sufficient roughness is required, usually with hard non-ferrous blasting particles such as alumina, garnet, and corundum.
Second, the proposed cleaning method for concrete/brick construction
Before the cleaning and painting, it must be ensured that the concrete building is strong and any surface defects are promptly repaired. The surface treatment of concrete is described in detail in Section 7 “Concrete Surface Coating” SSPC-SP13/NACE6 “Concrete Surface Treatment”. Before the cleaning, the concrete building was strong and any surface defects were promptly repaired. Section 7 "Concrete surface coating" also describes other related issues of concrete surface treatment. Remove loose contaminants from concrete surfaces using low-pressure water washing or steam cleaning (ASTM D 4258); used paints or other tightly adhered materials are cleaned by high-pressure water (ASTM D 4259). Sandblasting (ASTM D 4259 and D 4261) or acid etching (ASTM D 4260) can also provide concrete/brick construction with clean surfaces and appropriate roughness. Be careful not to use high pressure water cleaning or sandblasting. The grease can be removed with detergent or steam before sandblasting. The solvent cleaning method can only penetrate grease into the concrete. For non-aqueous coatings, the concrete building surface must be dry. The plastic covering method (ASTM D 4263) is the most common method used to detect building moisture.