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What Is Cobalt Blue?

J.E. Holloway
J.E. Holloway

Cobalt blue is a blue pigment made from one of a number of combinations of cobalt, aluminum and oxygen. Cobalt pigments produce a cool blue color, and were favored by painters such as Maxfield Parrish for painting skies. It is also an important traditional pigment in Chinese porcelain.

Cobalt blue pigment consists either of cobalt(II) oxide-aluminum oxide or cobalt(II) aluminate. These pigments are slightly different in their chemical composition, but both are the product of finely ground cobalt oxide and aluminum oxide, or alumina, being joined by a process known as "sintering." Pigment manufacturers grind the two substances, mix them together, and subject them to intense heat to bond them.

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Cobalt blue is the main pigment used in distinctive Chinese blue and white porcelain, known as qing-hua or "blue flower" porcelain. The earliest known examples of this type of pigment date from the seventh century in China, although examples of cobalt-based blue pigments are known from ancient Greece, Egypt and the middle east. Porcelain manufacturers imported cobalt from the middle east to make pigment. To decorate porcelain, potters first made the vessels themselves, then applied decoration by hand before glazing. Chinese blue-and-white pottery pigments are made from smaltite, a form of cobalt oxide, whereas most modern cobalt-based pigment uses cobalt aluminate.

Although Chinese porcelain had been made using cobalt blue pigment for centuries, cobalt blue emerged in Europe independently. Medieval European glassmakers added small amounts of smaltite to quartz and potassium carbonate to make the ingredients for a dark blue glass known as smalt. Although it produced a deep blue color in glass, smalt-based pigments were unsuitable for painting because of their tendency to fade over time.

In 1802, French chemist Louis Jacques Thénard discovered a slightly different form of the pigment, which became popular among painters. Mines in Norway and Germany produced the majority of Europe's cobalt, and these countries were known for their cobalt pigments. This pigment, based on cobalt aluminate, is the pigment most commonly referred to as "cobalt blue."

European miners had been aware of the existence of cobalt for some time. The name "cobalt" comes from the German word "kobold," which is the name of a type of mischievous goblin. Cobaltite and smaltite are common cobalt ores which are very difficult to work with. They contaminate other ores, can be difficult to smelt and can release highly poisonous dust. Due to the "mischievous" natures of these ores, they were named after the pesky underground goblins.

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Discussion Comments


@amsden2000 - Rhino beetles are also cobalt blue and man they get big!

You're right. Bugs are about the only natural thing that comes in cobalt blue. There are blue spiders, beetles, dragonflies and butterflies that are that brilliant cobalt blue.

I wonder if that's why they are used on old glassware designs? Chinese vases have a lot of butterflies on them and I've seen gorgeous cobalt blue wine bottles with dragonflies on them.

Cobalt blue is my favorite color -- so the more things that are that color, the better.


My friend has a cobalt blue tarantula as a pet. It is creepy and pretty at the same time. Its legs are iridescent blue and the body and "head" are white. It's one of those types of tarantulas that you can't hold though, since it's venomous. I never saw the appeal of keeping bugs as pets – they're kind of eery.

I always thought that the color blue didn't appear naturally in nature, but I guess bugs are excluded from that rule. I know that there are a lot of blue beetles, like the Egyptian scarab beetle.


@ElbowTickle - For cobalt blue wine bottles, it all depends on if you want a new one or an old one.

Places like ebay have lots of cobalt blue glass. You can hunt around for anything you want, you just have to check often enough to see the new posts. There are lots of private websites that sell blue wine bottles, but you'll have to find them.

If you want new cobalt blue wine bottles, try "Blue Nun" and "Resling" -- they both sell wine in blue bottles. They will probably be cheaper.


I love cobalt blue jars. They are very elegant. I like the classic 1800s Mason jars -- they are all made out of beautiful cobalt blue glass. My mom has several old ones that she keeps tucked away on the shelves in her living room and they always catch my eye. The ones she has are canning jars, but they still have their lids.

I was hoping to get her more blue glass for next Christmas -- does anyone know if the brand names of any cobalt blue wine bottles? I know they're out there, I just can't find the company that makes them.

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