covered hopper gray

[NW Mailing List]

On Thu, Jul 27, 2023 at 6:38 AM Jim wrote:

> Is the shade of gray used to paint covered hoppers specified anywhere?
> From photos it appears that it may have varied over the years or from class
> to class.  The early ones look quite light while later ones a bit darker.
> Also, does anyone know how to talk about the scale  of shades between white
> and black unambiguously?  A little looking on line seems to result in a
> chaotic mix of RGB values and photography/ painting discussions.  One I saw
> several times was neutral gray being defined as 16% reflectance.  Anyone
> able to bring some order to my confusion?
>

Can't answer to the paint colors but the "neutral gray" is a long-standing
standard in photography, especially black and white photography. A grey
card would be placed in a scene or under the lighting and the photographer
would take a light meter reading. That reading would be used to set the
aperture and shutter speed on the camera for baseline exposure results.

Bruce in Blacksburg
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