Mirror test for reflectivity - - -

Nick T.

New member
You may want to read the footnote first.*



Several months ago I realized that without spending a huge amount of money for laboratory grade measuring equipment, there was no way for me to effectively compare the reflectivity of various carnaubas and synthetic sealants. Hence the mirror test was born. The mirror test allows you to compare a constant level of reflection with the change in reflectivity caused by the selected paint care product.



Background:

A glass mirror has the silvering on the back surface of the glass; this provides the constant level of reflection. The front side of the glass provides a secondary reflecting surface whose reflectivity can be changed by applying the paint care product to be evaluated. Note that plastic mirrors have the silvering on the front surface, so they are not suitable for this purpose.



Methodology:

Start with a clean glass mirror. Touch the surface with a pencil point. Its primary reflection is separated from the point by the thickness of the glass, and there is a secondary faint reflection from the glass surface. Apply your carnauba or synthetic to half of the mirror and again compare the primary and secondary reflections. Repeat.



Things that can be learned:

1) The relative reflectivity of two products.

2) How many applications are needed for optimum reflectivity.



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*IMO all of these comparative product tests are supernumerary, superfluous, subjective, superabundant, supererogatory, and possibly supercilious! The only valid test is to apply the product to an area (hood or rear deck is best) of your car and then stand back and decide whether or not you like the appearance.
 
It works thusly:

The primary reflection (from the silvering) remains constant. The secondary reflection from the surface of the glass becomes stronger as the reflectivity of the glass is increased by the application of the carnauba or synthetic.
 
How do you know if it is getting stronger or weaker? Do you apply the wax (or sealant) in bands? Or do you have a really good memory.
 
freedre said:
How do you know if it is getting stronger or weaker? Do you apply the wax (or sealant) in bands? Or do you have a really good memory.

By comparing the secondary reflection to the primary reflection.
 
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