Hiding power

Hiding power of pigment in paint can be measured by refiectometry without the use of standard. It is calculated from the determined values of reflectivity and the scattering coefficient. 

According to ASTM D 2805-70, the hiding power of a layer is characterized by the ratio of the Y values (as defined in the CIE color system) over a black and a white patch of substrate. If this ratio is larger than 0.98, the layer is referred to as hiding. This criterion occasionally fails if applied to brightly colored pigments. 

A modern well-equipped color measurement laboratory can use the principle of spectral evaluation described above [1.52] to simulate this procedure with a computer. The thickness of the hiding film can then be calculated in advance from the reflectance curves of a single film on a black/white substrate at a known film thickness. 

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Optical. The optical properties of fillers and the influence that fillers have on the optical properties of filled systems are often misunderstood. The key parameters in understanding the optical properties of fillers themselves are filler psd, color, and index of refraction. These characteristics influence the optical properties of filled composition, such as color, brightness, opacity, hiding power, and gloss. 

Water-based flexo inks can be formulated with either a soluble toner or with the Day-Glo EPX Series which is a tme pigment and can be formulated like a conventional pigment dispersion. The Radiant Aquabest or the Day-Glo WST can be formulated in an alkaline water-soluble system to yield strong inks. They have limited shelf life and inferior fade, but do not necessarily requite additional binder. Day-Glo EPX must be formulated with a binder such as a hard resin or can be used with one of the soluble toners such as WST. The EPX Series has several advantages over soluble toners such as much superior fade, exceUent ink stabiHty, and some hiding power over kraft-type papers. A disadvantage of the EPX is its lower tinctorial strength than other fluorescent toners. 

The average particle size of coating-grade titanium dioxide is ca 0.3 p.m. Because this size is optimum for maximum hiding power and because of its... 

The abiHty of a coating to hide the substrate is called its hiding power. Hiding power of a uniform coating is expressed as the area of substrate that can be hidden by a unit volume of the coating (ft /gal or m /L). When the hiding power of a paint is low, several coats must be appHed to increase the film... 

Hiding power and tinting strength of a pigment also depend on concentration in the organic matrix. The concentration is usually expressed as the pigment volume concentration ... 

InstmmentaHy, both the hiding power and tinting strength can be determined from the amount of the incident light reflectance of coated white and black substrates. Relationships derived from Kubelka and Munk theory (6) are appHed in actual calculations. 

The choice of parameter used in the determination of size distribution should include consideration of the information needed in the interpretation of the data. For example, in the case of a manufacturer of paint pigment, the size parameter that best describes the hiding power (performance of the pigment) is the projected area of particles. A powdered catalyst manufacturer is primarily concerned with surface-area equivalence. 

Ultramarines ate iasoluble in water and organic solvents but soluble in acids, which cause their discoloration and the hberation of hydrogen sulfide. They have excellent permanency and resistance to alkaU but poor tinting and hiding power. 

As with textiles the principal reasons for the coloring paper are for aesthetic appearance and utihtarian purposes. Aesthetic appearance includes colored background for printed material, colored writing papers, colored household products to harmonize with interior decor, and many other diverse uses dictated by individual tastes. Utihtarian purposes include identification of multicopy forms, identification of manufacturer or marketer of specific materials or products, opaqueness or hiding power of packaged material, or to control consistency of paper manufactured from various colored raw materials. 

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