Talk:Red heat

«slightly»

That should read ‘very’: at 1000 °C the first table says ‘Orange’ but the second ‘Clear cherry red’ and at 1100 °C and 1200 °C the first table says ‘Yellow’ but the second ‘Deep / Clear orange’. So your temperature reading would be different by 100 K, or even 200 K.

Also, the figures in the second table come from Claude Pouillet 1836. 92.67.227.181 (talk) 03:07, 5 July 2022 (UTC)

I've consulted the source for the first table and it puts ‘orange red’ at the lower of the two values. Keeping that in mind the discrepancy shrinks considerably. It's also quite obvious that the strange °C figures are caused by a previous edition or source giving the figures in °F and that the article interprets the source in a messy way that wasn't intended.

Anyway, I've consulted seven different sources (Chapman, Pouillet, Halcomb, Howe, W&T, Ellern & Kemp) and compared them. For lower temperatures, the principal problem is terminology: how do I know that my cherry red is the author's cherry red? How dark is dark? Obviously, if an author's cherry is more orange than another author's cherry, it will also be lighter and he'll probably have a lighter dark red too. Pouillet gives no yellow, so with light orange he probably means a kind of amber. Howe skips orange... is his full yellow maybe orange or an orangey amber? Still, taking all of this in consideration, I think that below amber the differences in terminology don't reflect actual colour differences. Each of the colours is one that an author could plausibly use to describe the appropriate Planckian colour. (William Metcalf's remarks on the sloppiness of colour terms are particularly amusing.)

But in the amber to orange region, the temperature curve suddenly flattens. In this area, the differences between the authors are remarkably consistent: if the bend in the curve is in the amber region, their white will saturate near 1200 K, whereas if the bend is in the orange region their white will saturate near 1400 K. The only exception is Kemp which flattens much more smoothly, maybe because it's a pyrotechnical source.

The authors must have been basing their figures on materials with different emissivities. I'd like to integrate what I found in the article, but there are essentially two options: 1) Summarise all sources in one list of colours and temperatures, giving lower and upper bounds above amber. 2) Give all the sources explicitly. Because separate tables are hard to compare, they'd have to be put in a single table, but unfortunately that would mean throwing away the °F figures, because otherwise the table would become too unwieldy. — Preceding unsigned comment added by 92.67.227.181 (talk) 02:52, 7 July 2022 (UTC)

Also keep in mind that those are mere words. So we're talking about e.g. different people's different meanings of the word "cherry red" not differing attempts of trying to describe some fundamental reality.North8000 (talk) 13:11, 7 July 2022 (UTC)

That was what I meant with ‘an author's cherry is more orange than another author's cherry’. Have you read Metcalf's take on this? It had a nice understated sense of humour. 92.67.227.181 (talk) 14:35, 7 July 2022 (UTC)

Possibly merge with Thermal radiation?

See my comment here: Talk:Thermal radiation#Subjective color to the eye of a black body thermal radiator 92.67.227.181 (talk) 14:43, 7 July 2022 (UTC)