Paints surface preparation

Application Methods and Surface Preparation. Eor good durabiHty and performance, proper surface preparation and correct appHcation of house paints are as important as the formulation of high quaHty paint. Proper surface preparation prior to painting involves several considerations. Eor new constmction, proper installation and protection of the substrate material are necessary. Eor previously painted surfaces, preparation involves mostly cleaning and removing any existing paint that is unstable. Once surface preparation is complete, the appHcation process can begin. 

Field painting Surface preparation and painting operations of structural steel or other materials conducted at the project site. 

When the spectral characteristics of the source itself are of primary interest, dispersive or ftir spectrometers are readily adapted to emission spectroscopy. Commercial instmments usually have a port that can accept an input beam without disturbing the usual source optics. Infrared emission spectroscopy at ambient or only moderately elevated temperatures has the advantage that no sample preparation is necessary. It is particularly appHcable to opaque and highly scattering samples, anodized and painted surfaces, polymer films, and atmospheric species (135). The interferometric... 

Pa.ints, Paints (qv) prepared from poly(vinyl acetate) and its copolymers form flexible, durable films with good adhesion to clean surfaces, including wood, plaster, concrete, stone, brick, cinder blocks, asbestos board, asphalt, tar paper, wahboards, aluminum, and galvani2ed iron (147). Adherence is also good on painted surfaces if the surfaces are free from dirt, grease, and mst. Developments in emulsion polymeri2ation for paint latices have been reviewed (148). 

The painting procedure for other metal surfaces, although similar, the process of pre-treatment for cast iron components or non-ferrous metals, such as aluminium and copper, may need more care. The process of pre-treatment in such cases may vary slightly than for MS, as noted below. Such surfaces may require a change in the type of chemicals, their concentration and duration of treatment. The final surface preparation and painting procedure, however, will remain the same for all. 

Avoidance of the use of unauthorised thinners for paint dilution, surface preparation or cleaning of spray guns/brushes/rollers. Avoidance of skin contact and ingestion of chemicals by ... 

Protective coating Cladding Painting Plating Sensitivity to contaminants Suitability Type surface preparation... 

Application of protective paints consists of surface preparation of steel, priming coat and finishing coats. Wherever possible, steel should be blast-cleaned before painting. Primers thoroughly wet the metal to promote adhesion of finishing paints and carry inhibitive pigments. For example, red lead oxide will minimize the spread of rust on metal surfaces. The total thickness of fmishing coats must be at least 0.125 mm for adequate protection and life. Four coats of paint usually are necessary to achieve this. 

Bituminous This term is used for products obtained from both petroleum and coal tar sources but the petroleum products are the more widely used. These materials are very resistant to moisture and tolerant to poor surface preparation. They are only available as black, dark brown or aluminum pigmented. The last has reasonable outdoor durability but, without the aluminum, the film will crack and craze under the influence of sunlight. Normally they cannot be over-coated with any other type of paint, because not only will harder materials used for over-coating tend to crack or craze but there is also a possibility that the bitumen will bleed through subsequent coats. The best use is as a cheap waterproofing for items buried or out of direct sunlight. 

Therefore, unless they are specifically modified they require a higher standard of surface preparation than other types of paint. 

To state the means by which the required life of the coating is to be achieved. This includes surface-preparation standards, paints and systems, application, storage, handling and transport, quality control ... 

No. 12 Paint for the protection of structural steelwork No. 13 Surface preparation for painting... 

After suitable surface preparation, e.g. blast cleaning, low-alloy steels can be coated by paints, sprayed metal coatings, etc. and there is some evidence that such coatings last longer than on mild steel under similar conditions of exposure. ... 

Paint is the most widely used protective coating for steelwork and normally acts as a barrier between the metal and environment. The choice of type of paint and the final thickness required depends on the conditions of service, and the more severe the conditions the thicker and more resistant the paint film needs to be. Also the more sophisticated the paint system the more demanding is the surface preparation required. 

Designs should therefore avoid, as far as possible, all features that allow water (whether seawater, rainwater or moisture from any source) to be applied, entrapped or retained. These conditions are not only corrosive towards bare metals they also adversely affect the life of protective coatings both directly and by the fact that it is often difficult at areas subject to these conditions to give sound and adequate surface preparation for good paint adhesion and subsequent performance. 

The joint should be painted on both sides with the appropriate coating systems (following a suitable surface preparation programme). 

Svensk Standard SIS 055900-1967, Pictorial Surface Preparation Standards for Painting Steel Surfaces. 

The standard of cleanliness which must be achieved has been stated to be that which will allow the subsequent process to be carried out satisfactorily . As an example, the degree of cleanliness required to satisfactorily zinc plate from an acid solution is somewhat higher than that required prior to zinc plate from a high-cyanide alkali zinc solution. This should never be taken as a licence to skimp on surface preparation. However, the arguments over surface-tolerant paint coatings abound and will probably continue. It is to a very large extent true that problems of early failure in metal finishing are traceable to incorrect or insufficient surface preparation. 

The possible methods of surface preparation before painting hot rolled steel are discussed in the following sections. 

Spot and intermittent welding produces crevices in which corrosion begins and dirt builds up. These types of welding also create difficulties with the surface preparation required before paint is applied. Continuous welds are better. 

The outstanding virtue of zinc-rich paints is simplicity in application. No special equipment is required and the operation can, of course, be carried out on site, large or small structures being equally suitable for treatment. While there is some evidence that the zinc-rich paints will reduce iron oxides remaining on the steel surface, proper surface preparation is as important here as with traditional paints if the best results are to be achieved. The main use of zinc-rich paints is to protect structural steel-work, ships hulls, and vulnerable parts of car bodies, and to repair damage to other zinc coatings. 

Penetration of rust through an otherwise intact paint film is usually a result of inadequate surface preparation before painting, especially over weathered and hand-cleaned steel. However, superficial rust staining may be traceable to dissolved iron salts, e.g. in bilge water from a ship s deck. 

A consideration of the most important causes of paint failure must include the following inadequate surface preparation, application of the paint... 

Comparisons of Pretreatments-. A Background to the Corrosion of Steei and its Prevention, No. 3, Effect of Surface Preparation and Paint Performance , 20, The Corrosion Advice Bureau of B.I.S.R.A. 

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