With this post I want to start an irregular series discussing various pigments found in paints both modern and historical. Pigments span all of human history: red and yellow iron oxide are found in cave paintings, are probably among the first pigments people ever used—and yet are still found in paints today. On the recent end of the scale, a beautiful new blue pigment variously called Oregon blue or Yin Min blue (from its chemical composition, YInMn) was only discovered in 2009 and has only just started to come to market in paint form in the past two years. (It's actually not even available commercially in the U.S. yet, only from a paint company in Australia. It's also significantly more expensive than most paint at the moment due to its composition so I probably won't get my hands on any for a while, though I would like to do a post on it.)
One thing I didn't realize until recently was just how many historical pigments used by the Old Masters were actually quite toxic; painting used to be a pretty dangerous hobby! Thanks to modern chemistry, however, we're blessed today with a wide variety of non-toxic pigments with light-fastness and cheapness that the painters of yesteryear could only dream about.
For this post, I specifically want to talk about a relatively recent pigment (brought to paint form only in the 1920s or so), but an incredibly important one to the modern world. In paint form it's called Titanium White, which comes from the fact that it's simply titanium dioxide, TiO\(_2\). Titanium dioxide is estimated to be used in up to two-thirds of all pigments globally, because it has a reach far outside of art: its various properties mean that it's found as a coloring agent in things as diverse as foods, toothpastes, and sunscreen.
Titanium White
Titanium dioxide is a relatively common, naturally occurring substance. Oxygen makes up the largest portion of the Earth's crust by mass, and titanium follows in seventh place, so it makes sense that their combination is pretty abundant. Common ores include rutile, anatase, brookite, and ilmenite, and global production of titanium dioxide is in the millions of tons each year.
Titanium in general is a very safe metal, biologically speaking. It basically doesn't interact with the body at all, which is why so many implants are made out of it. Its oxide is likewise safe, and is used in all sorts of white food dyes as a result.
The whiteness of titanium dioxide is truly remarkable, reflecting nearly 100% of light falling on it at all wavelengths across the visible spectrum (though it starts to fall off a bit in the ultraviolet). Its reflectance is still high enough that it's used in sunscreens (it's what makes them so white) in order to give them their Sun-blocking power.
This incredible whiteness also makes titanium dioxide useful in paints, where it provides a great opaque white with amazing covering power. It can also be mixed with pretty much any color to lighten it (though it can overpower things if used too much). It's one of the first colors of paint I bought, and it's also the first one I've nearly used a whole tube of so far, showing just how much more of this pigment I use compared to everything else.
Due to its amazing coverage and reflectance, titanium dioxide is justifiably one of the most important pigments in painting, and in the wider world globally. One interesting tidbit of information about titanium dioxide that I couldn't fit in elsewhere is that M-class red dwarf stars are cool enough (only a few thousand kelvins) that they show bands of absorption from it in their atmospheres, adding a heavenly connection to this common earthly pigment. I've used it in most of my paintings so far, and that will likely continue to happen into the future! A hui hou!
(Oh, and I finished my star series of painting this week, so expect a post on them once I get around to getting some good quality pictures of them.)
No comments:
Post a Comment
Think I said something interesting or insightful? Let me know what you thought! Or even just drop in and say "hi" once in a while - I always enjoy reading comments.