molding-urethane.md

@@ -105,7 +105,7 @@ Indeed, in the blue channel of the image, the particles are nearly indistiguisha
 However in the red channel, we can clearly see that only the darkest particle effectively blocks the red light completely:
 ![DSC_2281__4_](uploads/06e1077e26c85f0f2e5d45fbbcf25854/DSC_2281__4_.jpg)
 
-In this case it is helpful to keep in mind that the stress-optic coefficient is a function of wavelength: coloration, in addition to stiffness and material thickness, controls the resolution and dynamic range of your photoelastic measurements.  Longer wavelength (redder) light produces fewer fringes for the same strain than shorter wavelength (bluer) light.
+Thus, darkly colored particles can be quite useful in application: a single photo, split by color channel, can provide a nearly monochromatic, darkfield polarogram for stress measurements, but also a high-contrast, brightfield image for the purposes of identifying particle locations.  When using this approach, it is helpful to keep in mind that the stress-optic coefficient is a function of wavelength: coloration, in addition to stiffness and material thickness, controls the resolution and dynamic range of your photoelastic measurements.  Longer wavelength (redder) light produces fewer fringes for the same strain than shorter wavelength (bluer) light. Thus, blue particles will be more sensitive, while red particles may facilitate experiments with greater inter-particle forces.
 
 
 Casting method