Mixed Greens

By cjohnson | November 22, 2005 2:35 am

green1Well, sometimes I wonder just how silly I can be. So you may recall that I was painting a deck a while back. Well, the next day, I discovered that the paint (which I got in the hardware store down the road and brought back on my bike) was not really the right green. It was too bright, too…bling, in fact. I’d suspected that might have happened. It was not the paint I used last year on another deck.

green2Plenty of time to repair the damage with the second coat; all I had to do was find the paint I used from the year before. I drove over to the extreme end of West Hollywood to find the right paint at the place I got it before. It did not work out: They only had it in small quantities, not at a great unit price, and I’m too cheap to pay to get four small quarts to make up the gallon I needed. (And I suspected I needed two gallons, in fact….other green stuff to paint.)

So the helpful gentleman in the hardware store tried to help by offering to match the paint shade and purpose mix what I needed, using the in-store computer. It would not work. The scanner that reads in the colours seemed not to be able to get the colour right, according to him. So I left, disappointed that I’d driven all that way for nothing.

Then I got home and realised that I’d been stupid. This is a bit of basic physics we’re talking about here, however indirectly….surely I could analyze it myself and figure out what I needed to take the brighter green I had and make it the right colour. I suspected (from my work with coloured charcoal and pencils in my dabblings in the graphic arts) that what it needed was a bit more red to render it a more “natural” green, and then overall some black to bring the overall brightness down. But I could not be sure. But I could simply test it! I took pictures of each and simply called them into Adobe Photoshop and did the analysis of the components (to be sure, this was just a guide…and yes, I’m aware of the difference between colour mixing of pigments vs colour mixing of light sources). Sure enough. More red needed. Such a simple thing, in the end. So I went back to my local hardware store down the road looking for red paint and found that there is a family of small tubes of mixers/dyes you can use for this. Lamp black and signpost red seemed to be about right.


So I made some “guestimates” of how much red and black I needed and mixed it up, making sure to do it thoroughly so as not to end up with a streaky deck. Night fell as I painted, so I could not be sure that I’d got it right. Next morning….. it worked! I got the colour exactly right, as I’d hoped (I’m sure there was a lot of luck involved). Why did I not think of that in the first place?


JoAnne, given your recent post, here’s the proposal then: Let’s start a series of physicists-do-DIY TV shows. Dead certain hit! We build a house from scratch every week. You can do the heavy fancy stuff like driving trucks and pouring concrete and building gutters and decks and the like, and I’ll mix the paint colours and do a bit of painting and also sort out the gardens. Sounds like a plan?


CATEGORIZED UNDER: Miscellany, Personal
  • http://countiblis.blogspot.com Count Iblis

    Not being colorblind can sometimes cause problems. :)

  • usc astro undergrad

    PBS has that show! although it’s mostly just clever tricks of the trade… if you smear shaving cream (cheaper the better) on you mirror, then wipe it off, it will never fog during a shower! PLUS! -water- -softener- and some foil makes your old silver spanking new clean in seconds! such magic, this physics :)

  • JoAnne


    You’re on! Thanks for giving me the fun stuff.

  • Mike

    Sometimes do it yourself is the only way. My wife wanted to touch up a couple of spots where she had moved pictures in the dining room. She went to Home Depot and bought the same exact color of paint. It was specified by brand, name, and a number. When she got home and put in on the wall, it did not match. I couldn’t see the difference, but she could. We compared the old can and the new. The brand, name and numebr matched, but it turned out the cans also showed the amount of each pigment and they disagreed. Apparently the company reformulated the color since we first bought it.

  • http://countiblis.blogspot.com Count Iblis

    Mike, you should do this test :)


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