[Tig] need 18% gray paint
jslomka at imageworks.com
Tue Feb 8 18:45:55 GMT 2011
Taken out of context
Date: Thu, 3 Feb 2011 15:46:24 -0600 (CST)
From: Bob Friesenhahn <bfriesen at simple.dallas.tx.us>
To: Mitch Jacobson <mitch at cat5tv.com>
Cc: tig at colorist.org
Subject: Re: [Tig] need 18% gray paint
Way back in college physics lab we built and used a spectrophotometer to analyze various types of light sources and most were quite "spikey"
and had gaps even though they looked close to white with the human eye. It should be expected that consumer paint may behave similarly.
Paint won't behave like this. What you were seeing in college was the phosphor excitation. The change of state in phosphors gives a very spiky radiometric signature. Paints are MUCH more broadband in their spectral response. It is very difficult to make a paint that behaves in that way that doesn't leverage interference effects between small particles. For the most part the pigments in paints will absorb large portions of the visible radiometric spectrum. This is very good for normal environments since it reduces illuminant metamerism. If that wasn't the case as the lighting in the room changes the color of the walls would change.
In looking for an %18 percent grey paint I talked to Anthony Calabria the color scientist for Benjamin Moore paints.
Thanks for reaching out to me. Our color number 2132-40 (Eclipse) is the closest we have to 18% reflectance with Y = 19. It's spectrally as flat as it can be since it's typically comprised of only black colorant. We have a store locator and an online store, both are at benjaminmoore.com. Feel free to respond on my behalf or point me to the thread you're reading.
That is close enough for DI work. In laying down paints you will have more issues with the application method then a %5.3 difference in refelectance.
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