The LRF (Luminous Reflectance Factor) is often confused with the LRV (Light Reflectance Value); sometimes the terms are even erroneously interchanged.
Primarily for safety reasons, Government agencies specify contrast requirements, mostly in interior applications. The intention of these regulations is to create surfaces that are visibly different and hence readily identified by the viewer - even those with vision colour deficiencies. The LRF is defined as the colour contrast between two material surfaces, and is calculated by mathematical formula that uses the LRV's of each material. As a general rule, the LRF will not be meaningful insofar as a Dryvit application is concerned.
Apparently various government agencies specify contrast requirements in all sorts of interiors (from public buildings to railcars).
Contrast in percent is determined by:
Contrast = [(B1 - B2)/B1] x 100
where B1 = light reflectance value (LRV) of the lighter area
and B2 = light reflectance value (LRV) of the darker area.
Note that in any application both white and black are never absolute; thus, B1
never equals 100 and B2 is always greater than 0.
Please remember: Light Reflectance Values, and therefore the resulting Luminous Reflection Factors, can differ between different finishes and supply plants!
Make sure you have the following information available:
Acknowledgements: Information offered in this datasheet has been obtained from Datacolor.com, Color Learning: From The Experts.