Talk:Cobalt blue

Where do the color codes come from? I haven't been able to find any reliable source on the Web. Yes, I found pages claiming that cobalt blue is such and such in RGB, but no evidence to back that up. —The preceding unsigned comment was added by 213.157.164.98 (talk • contribs).


 * There's no real reliable source for such, as cobalt blue cannot AFAIK be reproduced by a computer display. --jacobolus (t) 21:36, 20 September 2007 (UTC)

Focus on pigment, not color
This article should focus on cobalt blue as a pigment, not as a color. --jacobolus (t) 21:36, 20 September 2007 (UTC)

Well, it should definitely focus on one or the other. At the moment the intro paragraph mixes sentences about the colour and about the pigment without making clear which is which, with very confusing results. 216.75.183.13 (talk) 16:07, 26 April 2008 (UTC)

Added Sega's logo
Reference is in their site's fps. Sonic was also coloured the same to match the logo. Put it first then Nintendo DS because of dating. —Preceding unsigned comment added by 85.240.48.162 (talk) 17:47, 28 July 2008 (UTC)

contradiction
The header paragraph describes it as "slightly desaturated". The colour co-ords on the right hand boxout show it as having a Saturation value (under HSV) of 100%, and the RGB values bear this out as one of them is 0% (making it fully saturated). Which is correct, then?

Also, though it wasn't my addition, I couldn't help noticing what the above contributor wrote, and looking for the referenced entry in the history. Not sure why one of the world's most recognisable game characters is less notable than the opinions of some painter i've never heard of on the nowadays pretty moot subject of cobalt vs ultramarine? (The Sega logo and DS, less important I suppose, otherwise you could go on to list any number of logos using the colour and devices/items that are sold with that hue casing) 193.63.174.210 (talk) 17:26, 4 December 2008 (UTC)

obscure terms
Myself, I find terms like "slightly desaturated" and "stoichiometric" to be bringing in obscurity just for the sake of obscurity. Why not just be clear and direct about what matters about the colour, for instance that it is very stable. Some history would be nice, famous uses, etc. Good point about pigment versus colour. CheersBillyshiverstick (talk) 03:03, 29 June 2012 (UTC)

Mixup of blue pigments
This article is about the blue pigment formed by cobalt oxide and alumina, sometimes called Thénard's blue. It claims that in the first half of the nineteenth century Norway was a world leader in the production of "cobalt blue". The Norwegian product, however, was not Thénard's blue but smalt which is correctly described in English Wikipedia as a cobalt glass. Smalt was cobalt oxide fused with potash and quartz making a colored potassium silicate glass which was crushed to a fine powder. It was used particularaly for blue glazes on china but lost that market to a third blue pigment, synthetic ultramarine which was manufactured commercially beginning in the 1830's. To my knowledge, neither Thénard's blue nor synthetic ultramarine were ever produced in Norway. The historic "blue color" production is well-known in Norway today. Its chemistry, however, is not. Roufu (talk) 04:36, 13 November 2013 (UTC)
 * You may well be right. Norway is described in many pre-WP sources as the premier source of "cobalt blue glass" but that's a loose description that probably means cobalt (blue glass) not (cobalt blue) glass. The latter would be glass with cobalt aluminate in it. Does such a thing exist? Glasses have cobalt silicate mixes, and the aluminate is reserved for paint and porcelain glaze, no? So (cobalt blue) in glass is a misunderstanding. It's cobalt silicate = smalt that is the deep Bristol glass colorant. To clear up-- do you really think the world's biggest producer of smalt never added CoO to alumina instead is silica to make cobalt blue instead? Seems a natural business extention, as there was a market for the pigment in other uses. And if not why not ?? Next, suppose you did try to color molten glass with cobalt aluminate? Would it not work? Is cobalt aluminate-colored transparent glass unknown? I've looked at a lot of online old books (again you have to stay away from books repeating WPs mistakes) and they're so far been unhelpful. S  B Harris 08:23, 13 November 2013 (UTC)
 * The smalt production involved some 1200 people in the mining enterprise (some sources say more), but the chemical or glassworks part was not large. In the best years, around 1840, it employed about 70 people. It was German owned, used German technology and was run by a small group of Germans. In some ways it was like a colonial plantation. The first company went broke in 1849, the second one was British-owned and closed in 1855, and the third and final company only produced roasted ore concentrate which was exported to Germany for final processing. The mines closed in about 1898.
 * There were two people involved with the first company in the 1830's who might have had the ability to develop new products. The older one, Friedrich Roscher (1791-1859), left for a competing but smaller cobalt company that also went broke in the late 1840's. One of his sons then opened a highly profitable nickel mine in the same region. The younger one, Theodor Scheerer (1813-1875), went back to Germany (Berlin) for a Dr. Phil. (PhD) degree, then spent a few years teaching metallurgy at the University of Oslo. In 1847 he returned to Germany, where he became a professor at the Bergakademie Freiberg. He was an active scientist already in the 1830's. He described and analyzed several new minerals and was, in 1836, the first one to find nickel ore in Norway. He also published some speculative papers on the structure of minerals that are basically wrong. In 1886 his former student Clemens Winkler, who was by far the better chemist of the two, discovered the chemical element germanium.


 * A preliminary answer is thus that those few who might have developed new cobalt products chose to do other things.


 * So far, I have not looked into the production process for Bristol glass. Bristol glass has a different chemical composition from smalt, which was never used for making objects. Roufu (talk) 12:20, 14 November 2013 (UTC)

Spectrum
The spectrum in the graph shows a spectrometer reading from the brooch shown in the picture gallery. The colour shown in the image is incorrect, as it is coded by the camera as pure blue. The spectral power distribution clearly shows that cobalt blue is a kind of spectral purple (conventionally called violet), with a dominant wavelength of 456nm, calculated from CIE XYZ. Individuals with good colour vision will see this as blue with a degree of purple. The graph shows that the sample measured has a peak reflectance of about 35% of light in the lower wavelengths. This may be slightly higher as the same has a degree of specular reflectance. This gives it a glossy appearance, which can confuse the spectrometer to some degree. The graph shows the spectrometer sample 2x to illustrate what higher reflectance would look like. This would simulate looking at the sample under bright light. The measurement was taken with an xrite i1pro spectrometer in high resolution mode, which measures the spectrum at 3.3nm intervals from 350 to 740nm. TxB (talk) 14:19, 29 April 2018 (UTC)

This section can be improved by adding relevant citations from the literature on color. --TxB (talk) 16:33, 29 April 2018 (UTC)

Possible removal from list
An entry in List of colors: A–F contained a link to this page.

The entry is :


 * Light cobalt blue

I don't see any evidence that this color is discussed in this article and plan to delete it from the list per this discussion: Talk:List_of_colors

If someone decides that this color should have a section in this article and it is added, I would appreciate a ping.-- S Philbrick (Talk)  14:52, 23 August 2018 (UTC)