Color-dispersion staining

Plant fibers will show cells of color with the first order red compensator. The complicated color pattern reveals the complicated internal structure of the plant fiber and shows it to be a non mineral fiber. Occasionally, plant fibers show a single color when examined with crossed polars and first order red plate. In such cases, close observation of morphology or dispersion staining can be used to make a distinction. 

Zeiss and many other phase contrast microscopes produce the equivalent of a central stop dispersion stain by using a phase 2 16X phase contrast objective with the phase 3 condenser ring in place. Leitz manufactures a phase contrast microscope which produces central stop dispersion colors at 400X by using the number 5 condenser ring position. If the microscopes in use at other labs do not produce a central stop dispersion stain in this way, a "dispersion stainer" is available (36). The color resolution (not the particle resolution) of a McCrone dispersion stainer is a little better than that obtained from mismatching phase rings. 

These are organic fibers, usually plant fibers. Occasionally, plant fibers show a single color with a retardation plate which changes in color in a manner similar to asbestos. If morphology suggests the possibility of plant fibers, do a dispersion staining test. 

Tremolite and anthophylUte can be identified in 1.620 medium. In a talc sample where talc fibers may also be present, 1.605 medium is prefered. This will distinguish between talc fibers and asbesestos fibers by the dispersion staining colors. 1.605 medium will also distinguish between wollastonite and asbestos. 

A 1.547 medium is often used for examination of quartz by dispersion staining. This medium will show the F wave length color golden magenta (486.0 nanometers) for epsilon and the C wave length color blue green (656.0 nanometers) for omega as viewed with central stop. 

The dispersion staining colors described are for measurements at room temperature (25° C). It is possible to vary the index of the liquid by using a hot stage (46) and obtain a dispersion slope with a single particle without necessity of changing the mounting medium. This technique is also useful in analysis of other minerals including asbestos. 

If the refractive indices of the solid and liquid are plotted against wavelength, the color of the wavelength they intersect is shown in the central beam and the complimentary color in the divergent beam (Fig. 11). This technique is called dispersion staining. A dispersion staining device that has annular and central... 

Advantages Most stable synthetic rubber adhesive, excellent oil resistance, easily modified by addition of thermosetting resins Good heat aging and water resistance uniform appearance, non-staining light color, disperses easily in hydrocarbon solvents low cost Excellent adhesion at cryogenic temperatures and excellent retention of elasticity and shock resistance at these temperatures... 

Raw sienna -se- e-n9 [I terra di Siena, literally, Siena earth, fr. Siena, Italy] (1787) n. Naturally occurring iron oxide, limonite type ore. Color range, yellow to light brown, 40-70% Fc203. Somewhat translucent when dispersed in oil. General uses, tinting colors, artists colors, and stains. See iron oxides, natural. 

Synthetic organic dyes pigments), for example, disperse, fluorescent dyes color pigments stains... 

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