Introductory color mixing skills and the choice of color paste
Water-based color paste is a stable pigment suspension formed by organic and inorganic pigments and surfactants dispersed in water-based medium by crushing.
Inorganic color paste: most of them are iron oxide system; excellent in acid and alkali resistance, weather resistance, light resistance, etc. For example: Y42 iron yellow, iron black, R101Y/R101V iron red
Organic color paste: organic synthesis class; the unit price of color paste is higher, and the light and weather resistance of some color paste is lower; when using according to the order requirements; pay attention to the color paste with the choice of Y74\83 and R112 equal pigment number of color paste varieties are not recommended to use in the exterior wall; only when the 4% color paste additive amount can be used in the exterior wall. The technical department should be consulted immediately for specific applications.
For example: R254/112 Big Red, O73 Orange, BK7/6800HT Carbon Black, Y74\154\83\110 Yellow, B153 Phthalocyanine Blue, G7 Phthalocyanine Green, V23 Purple, R122 Rose Red, Titanium White (Titanium White has strong achromatic power and plays a role in covering up)
Color mixing application notes:
① Under the condition of ensuring the covering power, try to reduce the cost. That is, reduce the amount of color paste, but can not be unlimited to reduce the amount of color paste
l color paint to ratio greater than 0.95 can generally be judged to cover power qualified
l The deeper bright color paint should do the constructability test: the dry film color difference between rolling two times and three times is not big (experience judgment). Not included in the quality inspection test; but can be used as a reference.
② avoid floating color, flowering and other paint disease (consider the content of emulsion, titanium dioxide)
Finger research method: take 100 grams of white paint, add 2-3 grams of color paste to be tested, stir well, spread on the surface of the object to be coated, to be condensed, grind the surface part of the coating film with your finger, and wait for the film to dry, observe whether there is a color difference between the finger research and the place without research, such as a large difference, the color paste and the test paint compatibility is not good, the color paste is easy to produce the phenomenon of floating color paint. If the color is the same, generally will not produce floating color phenomenon.
Color system: 1. iron oxide system 2. blue-gray system 3. warm color system
Light color: the total amount of color paste is less than 1%, black paste is less than 0.5%
Medium and dark colors: the amount of color paste used is between 1% and 3%
Dark color: 3% or more (covering ability of 95% or more)
Note: Determine the main color, but does not mean that the main color color paste added more. Consider the inorganic class first, then the organic class.
When matching medium to dark color paint, reduce the amount of titanium dioxide in order to reduce the achromatic power and improve the coloring power. When adjusting particularly dark colors, use a white paint with close to “0” titanium dioxide content. Especially bright, bright colors use the amount of emulsion.
If you choose more kinds of color paste, the color will be grayish. On the other hand, if you choose less color paste, the color will be brighter and better saturated.
1. coloring strength of the color paste (coloring power)
Coloring strength is an important indicator, which reflects the color concentration of color paste, color spreading performance and pigment dispersion flocculation. The data is measured by the number of parts of pigment paste required for the color to reach 1/25 of the International Standard Depth (ISD), the smaller the value, the higher the coloring power. The value represents the number of grams of pigment paste required to be added to the white base coat: in emulsion paints – 25% titanium white content in white base coat (1/25ST)
2. Compatibility of the color paste (color spreading performance – finger study method)
The compatibility of the color paste with the system used is the key to affect the floating color blooming, flocculation and some surface defects of the paint film. If the fineness of the color paste is not enough and the dispersion performance is not good, it will affect the reproducibility of the color paint.
3. Dispersion performance of color paste (flocculation degree)
If the dispersion performance of color paste is not good, the difference of migration between pigment flocculant in color paste and white pigment and filler particles in base material is easy to show, and this difference often makes the pigment flocculant is no longer evenly distributed, when the film due to the small difference in temperature, density and surface tension inside the paint film, the pigment flocculant and the paint base naturally participate in this movement, and the pigment flocculant then separates, leading to floating color and flowering. If the color paste has good dispersion performance, it can avoid the generation of floating color and flowering.
4. The light resistance and weathering resistance of color paste
Light resistance: Grade 1 is the worst, Grade 8 is the best
Weathering resistance: Grade 1 is the worst, Grade 5 is the best
5. pigment content of color paste
The coloring power of the color paste and the pigment content are not simply proportional to each other. The same pigment content. The same pigment content, but the fineness of the different coloring power also has a great difference.
6. The fineness of color paste
Fineness is an intuitive indicator to reflect the coloring power dispersion effect and storage stability of the color paste. Generally, for the same pigment paste, the smaller the particle size, the larger the specific surface area, and thus the covering capacity increases, and the higher the coloring power; the smaller the fineness, the higher the gloss, and the better the dispersion effect and storage stability. Of course, the fineness of the color paste is not the finer the better, because when the particles become smaller, its specific surface area increases, the absorbed light energy increases, the degree of damage also increases, resulting in its weather resistance is reduced; and the particle size is too small in the coating film drying, with the precipitation of water, color paste together to the surface migration, easy to cause inaccurate color matching and wall color difference.
7. Acid and alkali resistance of color paste
8. The following factors must be considered when used externally: a. light and weather resistance; b. acid and alkali resistance; c. compatibility with the system; d. coloring strength, covering power and color spreading; e. color paste and color paste quality control matching; f. storage stability of color paste
