Stain

Stain is a discoloration that can be clearly distinguished from the surface, material, or medium it is found upon. They are caused by the chemical or physical interaction of two dissimilar materials. Staining is used for biochemical research, metallography, and art (e.g., wood staining, stained glass).

Types of Stains

Stains can be classified into two types: intrinsic stains and extrinsic stains.

Intrinsic stains are those that occur from within the object while extrinsic stains are those that occur on the surface of the object.

Stains in Biochemical Research

In biochemical research, staining makes visible certain biological structures, such as cellular or biochemical structures, that would otherwise be transparent. Staining is also used to highlight biological tissues for viewing, often with the aid of different microscopes. Stains may be used to define and examine bulk tissues (highlighting, for example, muscle fibers, connective tissue, and vascular tissue), cell populations (classifying different blood cells, for instance), or organelles within individual cells.

Stains in Metallography

In metallography, an alloy of interest is ground flat and polished to a mirror finish. The sample can then be etched in acid to reveal the microstructure of the metal. Often the surface is stained by that treatment to show the structure of the material.

Stains in Art

In the field of art, staining is used in the creation of stained glass. Stained glass is coloured by adding metallic salts during its manufacture. The glass is then crafted into stained glass windows in which small pieces of glass are arranged to form patterns or pictures, held together (traditionally) by strips of lead and supported by a rigid frame.

See Also

• Dye
• Pigment
• Bleach
• Stain removal

Stain Resources
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