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While glancing through the pages of Dyes and Pigments, there ought to be frequent occurrences of questions. Only a thorough explanation to such questions can give a fuller and in depth understanding of the various intricate processes that are generally associated with the dyes and pigments. This page exactly tries to give answers to all your thoughts about dyes and the dyeing process.
FAQ's on Pigments

What are pigments?

In biology, pigments are those substances which can give color to the tissues or cells of animals or plants. The most commonly available natural groups of pigments in the plant and animals groups, are called Carotenoid.

What are hinges?

With pressure sensitive tapes, prints cannot be glued or taped directly to a backing. For this purpose, hinges are used. Hinges are made of special archival tape, linen, or fine Japanese paper. All these methods use non-acidic, reversible adhesives, non-sticking.

How does particle size affect a pigment's dispersibility?

The sizes and shapes of particles of pigments have great impact on the colors of these pigments. But, these pigments are available in clusters form instead of individual form. The cluster pigments also effect the tinting strength and grind of these pigments.

Many different mechanisms are there, which hold the pigments together as a clusters. The most common mechanism is the soluble materials, and these materials cement pigment particles together in the drying process. When the sizes of the pigments particles start to decrease, theirs surface area also decreases and consequently, the electrical charge in these pigments increases. This increased charge in the pigment particles make them more dispersed.

What are the lightfast properties of the pigments?

The resistance characteristic of these pigment against the fading after exposure to sunlight, is called as lightfast property of the pigments.

What are Pigment Sticks?

The stick form oil paints are called as Pigment Sticks. These sticks consist of linseed oil, natural beeswax, and pigments. Generally, pigment sticks are highly fluid and very smooth. Sometimes, these sticks are also referred as Oil Sticks. These are used in drying the pigments.

What is the meaning of Luminescence?

Luminescence is a kind of property which is found in some materials. Through this property, these materials can trap the energy, act on it and then emit this energy as light. The emitting process my occur immediately or after long period of time in excess of thermal radiation.

What is the meaning of Fluorescence?

When a substance is exposed to exciting radiation and light starts to emit from the substance, then this process is called as Fluorescence.

What is the meaning of Phosphorescence?

After the cessation of excitation, the afterglow that can be detected by the human eyes, is known as Phosphorescence.

What is the meaning of Brightness?

In photometric term, the brightness can be expressed as a "luminance". Brightness is used to measure the emitted luminous intensity/unit area of a light source in millic andella/ m2 or foot-lamberts.

How does TiO2 provide opacity?

When all of the visible light that falls on a surface, is scattered, then only opacity is appeared. Titanium dioxide is considered as an efficient light scatterer. When there is enough pigment of TiO2 in an object or a film, only a small amount of light will be absorbed by the pigments or polymer and rest of the light will be striked off. The striked off light will be scattered outward and the system will appear as opaque and white.

What is the relationship between Phosphorescence and Temperature?

The light discharged by a phosphor, hugely depends upon the temperature. When phosphors are kept at high temperature, then for a short period of time, these phosphorus rapidly discharge light. But, when fully charged phosphors are kept at low temperature, then their light discharging rate gets slower. That is why, whenever it is required to test a matter, whether it is phosphorescent or not, the standard temperature is taken. The standard temperature is 23° C.

Which chemical and physical factors affecting the light fastness of pigments and dyes?

These following factors affect the light fastness of pigments and dyes:
  • The concentration of dyes and pigments.
  • Chemical as well as physical structure of these substrates.
  • Distribution of wavelength of incident radiation.
  • The atmospheric conditions like the humidity in the atmosphere and percentage of contaminants.
  • Distribution of wavelength of the incident rays.
  • The rate of diffusion of the volatile substances in the polymer.
NOTE: The lightfastness of the pigments and dyes do not depend upon the pigment or dye, but depends upon the whole system.

What makes one grade of TiO2 different than another?

There are different grades of Titanium dioxide which are available. These different categories of Titanium Dioxide are due to the difference in their particle size and their surface treatment.

What are the prescribed directions while using dry pigments?

For methods of using dry pigments (or other non-colored powdered additives) which require only as much mixing as is possible with a brush. These methods can be applied for solvent or water-based paints. It will not achieve the level of ground pigments, but can suffice. Making the crude version of a pigment dispersion.

Manual grinding with a glass muller on a glass surface is recommended (see- Grinding) Make a paste with dry pigment, water and disperse water for water based paints or dry pigment, stand oil and disperse oil for oil base.

Will the organic color pigments stain the clothes or sheets?

The color organic pigments are not stains nor these are dyes. So, if some stains arise in the clothes or sheets, then after some time these can be washed-out completely from any synthetic materials. These stains can be removed very easily.

What is a mixed metal oxide (MMO)?

MMO is a kind of inorganic pigment. These type of pigments contain more than one types iron metals in their oxide crystal structure.

What is a CICP?

CICP are also a kind of pigments. These are Complex Inorganic Colored Pigments.


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