Manufacturers are forced to constantly increase the competitiveness of their products due to the current saturation of the market with imported and Russian materials. Therefore, simultaneously with quality properties, decorative requirements are also imposed on the products.
Definition
Iron oxide pigments are an inorganic type of substance consisting of hydrates of oxides and oxides of different levels of valency. According to the production method, they are divided into natural and synthetic. Compared to natural ones, the latter are used much more often. This is justified by the high content of dyes in the synthetic type pigments and low cost. Iron oxides have a wide variety of colors: from black-blue to yellow and green tones.
Iron Oxide Pigments: Characteristics
Among the properties of pigments, it is worth noting the following:
- Hiding power reflects the expense to cover a unit of the plane. The lower this indicator, the less substance will be spent.
- Dispersion. With a decrease in grinding fineness, coloring ability increases.
- Intensity is the ability to convey its own shade when mixed with other substances of a certain saturation. The intensity is displayed as a percentage of the standard deduced by the manufacturer.
- Light fastness is resistance to photochemical influence.
- Constancy. Regardless of the party, the shade should not change the intensity.
- Heat resistance is the ability to preserve color in a set temperature range.
- The presence of water-soluble additives.
- The acidity of an aqueous suspension. It should not exceed the optimum pH = 7. Due to the fact that cement is characterized by an alkaline reaction of the medium, due to the use of substances with low acidity, the mixture will be completely discolored.
Concrete painting
For painting concrete products, iron oxide pigments have been used for a long time, having low hiding power and a distinctive coloring characteristic. They are not affected by alkali, certain types of acids, salts, or sunlight. Thanks to this, pigments have become so common when painting cement hydration items.
In stores, iron oxide pigments of foreign and Russian production are presented. To give concrete a shade, depending on the region of manufacture, the introduction of substances from 3 to 15% of the total weight is required. It should be borne in mind that pigments have a greater dispersion in comparison with Portland cement, so if you exceed the established concentration, there will be a sharp increase in the need of the mixture in water, which will subsequently lead to a significant decrease in pour strength and an increase in porosity.
Iron Oxide Pigment: Application
The technical data of the equipment affects the efficiency of the use of dyes. With a small proportion of the pigment in the bulk, equipment that has a high mixing speed is necessary to obtain complete dissolution. The pigment changes the color of only the cement binder from the entire concrete mixture, so the same amount of pigment will more intensively color the mixture with a significant cement content than a mass with a small amount.
Two or more pigments are used to create shades of cement that differ from the tones of individual dyes. The use of a combined type of coloring requires mixing before entering the material to obtain the desired shade. This will take more time than coloring with one pigment.
Basic dyes
The yellow iron oxide pigment has resistance to weathering, light resistance, thermal stability, excellent coloring characteristic. It is used in the manufacture of concrete products with various purposes, tiles, plasters, roof tiles, many types of primers. Czech and Chinese dyes have similar consumer properties, while the latter are in the lower price segment. Such pigments, created on the basis of ocher, are distinguished by a granular stable composition.
Black iron oxide pigment is a persistent chemical substance that has found its application in the manufacture of colored cement products, fillers, paints. The dry type of the dye is distinguished by its covering characteristics and tone depth, while it does not fade and is not subject to temperature influence, an increased level of alkali. Finished products get agate resistant tone.
Red pigment is produced mainly by Czech and Ukrainian manufacturers in the form of a powdery inorganic compound. The base used provides durability and saturation of the shade.
White coloring matter does not dissolve in organic acids and water, and is also not toxic to humans. It is realized in most cases in 25 kg bags.
What determines the degree of staining
The color of the finished product is influenced by the shade of the cement itself. The gray tone has the ability to dim the brightness, so when working with standard Portland cement it is difficult to get rich colors. The best option is white cement, also used to create blue and green shades.
Each type of material has its own gray color. Different manufacturers also produce cement of the same type, which varies among themselves. Such differences are visible on painted concrete, while light material is more sensitive than concrete with dark iron oxide pigments. So, for one batch of products from this material, the same cement from the same manufacturer should be used.
The tone of the filler may also affect the final shade of light products. Here, the rule of a single composition is relevant when producing one batch of goods. There is a significant decrease in this effect in black and blue concrete. The color is not greatly affected by the density of the material, but with poor compaction of porous concrete, there is a possibility of efflorescence during storage and use. Their appearance worsens the appearance, they do not affect pigments, but efflorescence is much more noticeable on a painted surface than on a natural one.
Ratio of components
In the preparation of the cement tint mixture, the dosage of the substance by weight should be taken into account, since iron oxide pigments for concrete have different densities. It is also important to maintain an equal period of mixing, this will allow you to evenly color the mixture.
Different curing conditions result in a color change. A different shade may appear due to the rapid evaporation of moisture and condensate on the plane, there is also the possibility of a slight plaque. To obtain the desired result, compliance with the proportions of water for the dilution of concrete and the temperature regime are required. There is one characteristic pattern: needle crystals are characterized by a high pour point. Small crystals enhance the diffusion of lighting, which is why the color looks lighter than the tone of similar concrete, solidified at low temperature.
Pigment types
Iron oxide pigments are usually divided into weak, the total critical concentration of which is 25%, and conditionally strong with a concentration of 10%. If it is necessary to obtain a specific shade of more than 10% of the coloring matter from the volume of the material, it is desirable to use a smaller proportion of the pigment of a strong type. This is due to the fact that a large proportion worsens the strength characteristics due to increased water absorption.
To create pastel concrete products, it is difficult to establish small proportions, so it becomes rational to use a full portion of a conditionally weak coloring material.
Manufacturers
Among the main manufacturers are leading German, Czech and Chinese plants. In terms of price-quality ratio, Chinese-made pigments are more attractive today. The most common among Czechs are red and brown tones. In terms of quality, the first place is occupied by German coloring substances, but because of the high cost, their use for paving is unprofitable.
Iron oxide pigments (made in Russia) have a low price and satisfactory properties, so that they are worthy of competition with imported ones.