Crayons under the spectrophotometer
September 20, 2011 4:54 PM   Subscribe

Starting with a fresh box of twenty-four Crayola crayons I measured each with an i1 pro spectrophotometer to create a set of spectral power distributions (SPD) of the reflected light.
posted by rhapsodie (19 comments total) 19 users marked this as a favorite

 
I just dropped in to say that "spectral power distribution" sounds like a plot point from a late 80s poorly dubbed anime.
posted by hippybear at 4:56 PM on September 20, 2011 [5 favorites]


I love entries about crayons, and I especially love it when clicking the "crayons" tag led me to rediscover something I linked about crayons and 100% forgot ever existed.

In brief, I love entries about crayons.
posted by Joey Michaels at 5:02 PM on September 20, 2011 [2 favorites]


This person and Spiderman both hating on the "useless" white crayon?! Why no love for the white crayon?

Surely I can't be the only one out there pasty enough to have to color over peach crayon with white to achieve an accurate skin color match? You people and your melanin.
posted by phunniemee at 5:06 PM on September 20, 2011 [2 favorites]


Surely I can't be the only one out there pasty enough to have to color over peach crayon with white to achieve an accurate skin color match? You people and your melanin.

When I was a kid I always ran out of Mediterranean Demigod before all the other colors :(
posted by Greg Nog at 5:13 PM on September 20, 2011 [5 favorites]


White crayons are also awesome on colored construction paper.

They are also useful during easter egg dyeing.
posted by hippybear at 5:13 PM on September 20, 2011 [2 favorites]


I believe that "spectral power distribution" is, in fact, the process by which the holy spirit impregnates young virgins to bear christs.
posted by symbioid at 5:47 PM on September 20, 2011 [1 favorite]


I immediately tried to find an image online of the "Peanuts" comic strip in which Linus "makes a cup of cocoa" for his sister Lucy by dipping a brown crayon in hot water, as the basis for a brilliant joke regarding the precise shade of brown needed so that one didn't have to dip the crayon twice...alas, I failed. :-(
posted by Greg_Ace at 6:47 PM on September 20, 2011


Greg, via a description on Facebook, the joke seems to have been that Lucy complains the hot chocolate Linus has prepared tastes terrible, it's weak, it tastes like you just dipped a brown crayon in it. Linus tastes, and says, you're right, it is weak, I'll add some more crayon. Can't find the 'toon either, though.
posted by beagle at 7:07 PM on September 20, 2011


According to that chart, the brown crayon is, indeed, very brown.
posted by evidenceofabsence at 9:14 PM on September 20, 2011


This is (actually) confusing and bizarre. "Spectral Power Distribution" refers to light emitted by things like lamps, which makes no sense as crayons don't usually emit light. And you certainly don't measure SPD with a spectrophotometer, which measures transmittance or absorbance.

What (s)he's presented here looks like reflectance spectra, which you'd measure with some kind of spectrometer referenced against some sort of calibrated reflection source for the given illumination field. That would make some sense. But other than that I have no idea what (s)he means.
posted by zomg at 9:18 PM on September 20, 2011 [1 favorite]


I'm pretty sure spectral power distribution refers to the spectrum of any light (or other signal; it's used a lot in electronics or signal processing), regardless of whether it's emitted directly from the object of interest or reflected. The spectrophotometers I've played with do measure an arbitrary light input; they don't care if it was directly emitted by something or if it bounced off a crayon first. Of course if you're interested in the material's own properties, the power distribution of the reflected light is only useful if you know what the incident light was— I'll just assume that he used some reasonably daylight-like thermal light source.

What one really wants to know is the absorption and reflection spectra of the crayon; this will let you know what range of colors you can produce by using the crayon more or less heavily on a piece of paper (of known properties under a known illuminant etc).
posted by hattifattener at 9:49 PM on September 20, 2011


He seems like he is a bit confused. It looks like reflectance spectroscopy but SPD is just one of several independent variables related to adsorption and reflection spectra it looks like he is actually measuring and he wouldn't measure that anyway with a spectrophotometer. It doesn't look like its his fault exactly, he is probably just telling us what he understands this product to be telling him.

I know this looks sciencey but this just seems like some dude with an expensive tool he doesn't understand and an arrogantly named blog making a graph from what is very likely to be poor data, labeling it wrong, and calling that shit gold.
posted by Blasdelb at 10:06 PM on September 20, 2011 [3 favorites]


Hey kids! Ask Mom if you can be the first one on your block to experiment with Crayola Marker Chromatography, Colors Inside Colors, and amazing Color Changing Milk.

If you're good little Einsteins and say "Pretty please" (and promise to help clean up the mess), maybe you can help her bake some great Rainbow Cookies as a treat. Have fun!
posted by cenoxo at 10:17 PM on September 20, 2011


Love this.
posted by alby at 12:08 AM on September 21, 2011


Starting with a full box of Crayola crayons, I put them to my nose, inhaled their crayon smell and was transported back to my primary school class when all that mattered in the world was the red houses, the greens grass and the blue sea on the white paper.
posted by GallonOfAlan at 1:35 AM on September 21, 2011


I just dropped in to say that "spectral power distribution" is the name for my new band.
posted by Fizz at 4:35 AM on September 21, 2011


I was going to do this, but I ate my crayons.
posted by the quidnunc kid at 4:57 AM on September 21, 2011


That was probably the coolest link I'll see all day. No longer will I wonder where my Crayolas lie in the sRGB gamut. I may have to send the author a larger box of crayons.
posted by kaszeta at 5:39 AM on September 21, 2011


On the plus side, and in spite of the technical difficulties with the process, I now know about nodebox
posted by nonspecialist at 8:41 AM on September 21, 2011


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