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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
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.
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.
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.
The resistance characteristic of these pigment against
the fading after exposure to sunlight, is called as lightfast property of
the pigments.
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.
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.
When a substance is exposed to exciting radiation and
light starts to emit from the substance, then this process is called as
Fluorescence.
After the cessation of excitation, the afterglow that can
be detected by the human eyes, is known as Phosphorescence.
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.
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.
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.
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.
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.
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.
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.
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.
MMO is a kind of inorganic pigment. These type of
pigments contain more than one types iron metals in their oxide crystal
structure.
CICP are also a kind of pigments. These are Complex
Inorganic Colored Pigments.
