All You Need to Know About Cobalt Blue

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Blue Cobalt is a transition metal that has been used to impart a blue hue to things when used as a pigment. It is found in magnets and cancer medications too, and recently has been implemented in nanoparticles as well. The blue color imparted is rich in contrast to other blue pigments and has been noted for its consistency over larger bodies of work. Many noted painters have lauded the use of the pigment in their paintings sheerly for the brilliance that it imparts to them. But a fair bit of precaution is needed while dealing with cobalt blue because if ingested or inhaled, it can be toxic to humans.

In its purest form, cobalt is brittle and looks like a mixture of silver and blue in color. It is similar to iron in its magnetic properties and is therefore used to make some very powerful magnets. Cobalt-60, a man-made isotope of cobalt, is often used in cancer treatment as it can target and kill tumors. This is especially useful in the cases of brain cancer where surgery is not possible in all cases.

How It Is Made

Cobalt blue can be obtained by sintering cobalt oxide with aluminium oxide at 1200 C. When speaking chemically, Cobalt Blue is CoAl2o4. It is brighter and less intense in saturation as compared to Prussian blue, which is derived from iron-cyanide. Cobalt blue is extremely stable and throughout history has been used as a coloring agent in jewellery, pottery and paint. There has been evidence of glass being tinted with smalt, which is a silica-based cobalt pigment. In fact, most of these blue objects in the past have had cobalt blue somewhere or the other.

Arts and Civilizations

When it comes to Chinese porcelain cobalt blue has had a significant impact on the culture’s pottery and vessels. Cobalt blue as reference was first noted in 1777, and was later also discovered as an alumina-based pigment by a Frenchman named Louis Jacques Thenard. France was one of the first countries to commercially produce the metal. In 1807 a Norwegian company by the name of ‘Blaafarvevaerket’ became the leading manufacturer under the leadership of Benjamin Wegner. These blue objects were very desirable to own at these times.

Prominent watercolorist John Varley has time and again said that cobalt blue is a great substitute for ultramarine, especially for painting skies. In his “List of Colors’ (1818) he says when used in place of ultramarine, cobalt blue brighter and much more consistent. This is due to its superior contrast and brilliancy. Blue objects come to life due to the pleasant and vibrant hue that cobalt imparts.

Another famous painter Maxfield Parrish uses the color to paint the intensity of his skyscapes. This is also the reason cobalt blue is sometimes called Parrish Blue too. Even in 21st Century cobalt blue is used extensively in home decors and architecture for its vibrancy. Adding blue objects to your everyday day life brings a sense of serenity to you.

Cobalt has been used in ancient Chinese pottery and many other civilizations without people knowing that it was a different material altogether. In 2014, blue glass beads were found in a Danish grave, which was 3,400 years old. The same metal has been found in Egyptian tombs, even in King Tutankhamen’s tomb. Being found in opposite sides of the world means that there could have been trading of cobalt in the early ages. This helps in establishing the fact that cobalt could have been a precious or semi-precious metal (In the form of blue objects) historically known for its pigment and hue. Interestingly this also indicates there might have been trade routes that we are not aware about or how colors and metals transcended different cultures.


Aside from these ancient origins, cobalt was not discovered and classified as a different metal until the 1730s. Until then, the pigments of hues made from cobalt were known as smalt or safflor. These were thought to be made up of bismuth, copper, arsenic and iron. It was only when the Swedish Scientists Grorger Brandt acquired a blue object from some ore from his family’s mines, the world got to know about cobalt.

Brandt later described the metal and its properties, which included its magnetism and what would happen if we dissolved cobalt into ammonia. It turns red as the records show. There was a lot of controversy surrounding how it was discovered and whether it is a different metal altogether or not. It was Torbern Bergman, a fellow Swedish scientist, who cleared the air. Bradt’s family-owned those mines, which is the reason his contributions were often scrutinized. Many people suspected that it was not him but some worker that must have gotten it out.

When it comes to isotopes Co-59 is the only stable isotope of cobalt. This does not mean that radioactive cobalt does not exist or occur naturally. In 2014, Co-56 was discovered in a supernova that is 11 million lightyears away from us. The isotope has a half-life of 77 days and then it turns to iron-56.

Present-day Uses

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Oxygen Absorbing Cobalt

Although associated mostly with pigments, cobalt is used in many modern technological types of research and devices. In 2014, scientists in Denmark created a crystalline material that could absorb all the oxygen in its proximity. It also has the ability to release as it wishes. 10 liters of this material can suck all the air present in the room. They compare it to the function of hemoglobin in the blood and how it absorbs oxygen.

If this air sucking cobalt products wasn’t enough, American researchers are working tediously to use and integrate this metal into food safety protocols. The current food testing process is slow, complicated and wasteful. With the help of cobalt, scientists have found a way of isolating bacteria.

Cobalt and Bacterial Isolation

Before this discovery, food inspection needed a sample of the food in question and then it had to be isolated and cultivated for bacteria. This process takes 24-48 hours, which meant that most of the fresh fruits and vegetables would go stale while the culture is being developed.

Sam Nugen, a scientist, has come up with a great solution to this problem. Nugen and his team have developed a peculiar way in which the cobalt-iron nanoparticles are attached to the bacteriophages (viruses that infect bacteria).

These bacteriophages can lock on to bacteria like E Coli and then Nugen and his team can use a magnet to extract all these bacteria from the food. This is essentially yanking those bacteria out of the food sample.

This process is based on the magnetic property of cobalt and has the potential to revolutionize how to food inspection is done and make it much faster and efficient. The idea is to perfect the technique so that there are no traces of either bacteria or the metals present.

The technique has been a success and Dr Nugen has managed to secure a grant of half a million dollars to refine the process. There is a YouTube video available which documents the whole process and people get to see its functioning. The novel idea can reduce testing times drastically as it only needs 12-15 hours for the bacteriophages to infect the bacteria.

Nugen says with the advancement of nanotechnology, they will be able to create bacteriophages that do this work even faster. Optimistic about it uses, Nugen aims to bring the process to the public soon. This might just be the biggest thing in the coming years as nanotechnology advances further.

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