White surface finish

A near white surface finish corresponds to Swedish standard Sa 2-1/2 or BS4232 second quality. This finish is defined as one from which is removed all oil, grease, dirt, mill scale, rust, corrosion products, oxides remaining coatings, except for a very light shadows of light streak discolouration. At least 95% of the surface shall have the appearance of a white metal surface finish and the remainder shall be limited to light discolouration. 

The interior surface finish, to comply with EEC and other health standards, must be rustproof, cleanable, and free from any crevices which can hold dirt. Bare timber in any form is not permitted. Most liners are now aluminium or galvanized steel sheet, finished white with a synthetic enamel or plastic coating. GRP liners are also in use. Floors are of hard concrete or tiles. Very heavy working floors may have metal grids let into the concrete surface. Floor concrete is coved up at the base of the walls to form a protective curb. 

P. Bindra and J. R. White, in Electroless Plating Fundamentals and Applications, Ed. by G. 0. Mallory and J. B. Hajdu, American Electroplaters and Surface Finishers Society, Orlando, FL, 1990, p. 289. 

Surfaces destined for reuse Surfaces destined for smelting NACE Visual Standard No. 2, Near White Blast Cleaned Surface Finish NACE Visual Standard No. 3, Commercial Blast Cleaned Surface Finish... 

The color of the wax will affect the color of the finished product. A Lovibond Tintometer is often used for color measurements, whereby the color of the raw material is compared against a series of colored standard glasses, under a standard light source. The color of the solidified wax of the same sample may be different depending on the amount of occluded air, the rate of cooling, or surface finish. Therefore, the color of many waxes is best measured in the molten state. Two ASTM color standards are used to measure dark-brown to off-white color and off-white to pure white. The refractive index and the specific gravity are other parameters often determined. 

Carbon steel substrates must be sandblasted to a near-white metal finish (SSPC-SP10 or NACE 2) and maintained at least 5°F above the acid dewpoint during installation. Concrete surfaces must be free of any imperfections such as blow holes or honeycombing. Old concrete must be free of oil, grease or chemical contamination. 

Steel surfaces do not provide any unusual difficulties during coating operations, as long as the steel is of high quality and the environmental conditions are strictly controlled. Specifications usually call for an abrasive blast that meets Steel Structures Painting Council (SSPC) Spec. 5 ("white metal") finish although steel to be used in non-nuclear areas usually receives an SSPC 10 ("near white") finish or an SSPC 6 ("commercial") finish. Areas that require special attention are welds, seams, edges, channels, etc. 

General description PVF is available only in film form. DuPont Tedlar films are available in clear, translucent, or opaque white film and in several surface finishes. 

Reflective coatings reflect the incident radiation and what is not reflected is absorbed or transmitted. If there is spectral reflectance, the surface is a mirror. If there is scattering, the surface is a diffuse reflector like a white paint. For deposited metal films, the difference is generally the surface finish - a smooth surface is necessary to make a good mirror. 

Joint areas are also prepared during surface preparation. For instance, with bell-and-spigot-type PCCP, the inner concrete is first demohshed to expose the steel liner at both the beU and spigot ends. The extent of the demohtion depends on the thickness of the inner-core concrete and the required bond length at CFRP terminations. Adequate area is to be demolished to allow for the type of transition called for in the design. The steel surfaces at termination detail areas are also prepared to at least a near-white metal finish. 

The main difference between the two types are that the reaction products of the silico fluoride types are less soluble in water and are also harder, which may give better in-service performance but at a slightly higher material cost. However, with recent developments in floor-laying techniques, the concrete substrates for industrial floors are laid with much more dense low-porosity surfaces, so that neither silicate nor silico fluoride treatments are as effective as they used to be, when the concrete used had a slightly more open finish and hence was more receptive to these treatments. With modern concrete floors, it is imperative to wash any material not absorbed into the surface within a short period. Otherwise, unpleasant white alkaline deposits, which are difficult to remove, may occur. 

Glass-reinforced aluminum foil with either a bright polished or white lacquer surface is utilized with most types of insulant. Primarily it is used as a vapor control layer or as a means of upgrading the fire properties of plastic foams, but it does give a semi-decorative finish to the insulation. It is therefore often use where the insulation is open to view but located away from direct risk of mechanical damage. 

Various finishes can be achieved — gloss, satin (or egg-shell) or matt. This is accomplished by the addition of particles of size 1-5 pm of, for example, silica, china clay or the white pigment, TiCK The degree of mattness depends on various factors, such as particle size, surface treatment of the particles, rate of film formation, and the polymer composition, e.g., urethane/acrylate compared with epoxy/acrylate. The former requires smaller particles larger particles cannot be used as they create a rough surface. 

---