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Author: Subject: Chemical colour references
Sulaiman
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[*] posted on 6-10-2020 at 05:59
Chemical colour references


When photographing or videoing chemicals my phone camera (like most) does an attempt at white balancing,
so depending upon lighting, background etc the colours of chemicals or solutions are not 'true'.
A set of 'standard' colours in the background would allow true colour correction or comparison.

So I am looking to make a rainbow of colours that can be used as a reference.
Ideally the colours should be reproducible by anyone anywhere and be long term stable.
So far I have only got blue copper sulphate e.g. 0.5M solution.
Solutions of other coloured chemicals that I am familiar with are subject to oxidation or reduction (e.g. methyl blue, methylene blue, dichromates etc.)
This must have been done before but a quick Google search failed.

Can you suggest stable chemical solutions of various colours?




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pantone159
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[*] posted on 6-10-2020 at 06:49


Darren L. Williams et. al., 'Beyond lambda-max: Transforming Visible Spectra into 24-bit Color Values'.
Journal of Chemical Education, Vol 84, No 11, Nov 2007, p1873-1877.

A student laboratory experiment to measure the transmission spectra of some common chemical solutions, and determine the rgb values. The experiment used solutions of 1M CoCl2, 1M NiCl2, 1M CuSO4, and 0.005M KMnO4. That covered red,green,blue,purple. The KMnO4 might not be stable.

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macckone
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[*] posted on 6-10-2020 at 07:44


Get a pantone color swatch card or set.
Or you can buy select color swatches.
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[*] posted on 6-10-2020 at 08:41


The amine complexes of copper and nickel will be stable long-term.



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pantone159
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[*] posted on 6-10-2020 at 09:11


The card macckone mentions might be the MacBeth ColorChecker card. It is a card with 24 different color swatches, specifically designed for calibration of photos/video. They are not super cheap, I think in the range $50-$100, presumably because they are careful about using the right inks so the colors are really correct.
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mayko
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[*] posted on 6-10-2020 at 10:48


I picked up a few of these but never really used them. Recently I've been thinking about the same sort of thing, how to convey & measure qualitative color:

https://www.adafruit.com/product/1334




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[*] posted on 6-10-2020 at 11:00


Any help?
https://en.wikipedia.org/wiki/Pt/Co_scale
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[*] posted on 6-10-2020 at 11:36


Quote: Originally posted by Sulaiman  
Solutions of other coloured chemicals that I am familiar with are subject to oxidation or reduction (e.g. methyl blue, methylene blue, dichromates etc.)


Dichromates/chromates form stable solutions.




If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

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wg48temp9
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[*] posted on 6-10-2020 at 22:26


Quote: Originally posted by pantone159  
Darren L. Williams et. al., 'Beyond lambda-max: Transforming Visible Spectra into 24-bit Color Values'.
Journal of Chemical Education, Vol 84, No 11, Nov 2007, p1873-1877.


Thanks pantone, thats a useful reference on the subject of defining colour.
Attachment: defining-colour-williams2007.pdf (1.7MB)
This file has been downloaded 18 times
and a useful file on white balancing algorithms ? sorry the file will not load, I will try in a new post.

[Edited on 10/7/2020 by wg48temp9]




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wg48temp9
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[*] posted on 6-10-2020 at 22:46


and a useful file on white balancing algorithms
Attachment: AutomaticWhiteBalanceAlgorithmsforDigitalStillCameras-aComparativeStudy.pdf (3.8MB)
This file has been downloaded 16 times




i am wg48 but not on my usual pc hence the temp handle.

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[*] posted on 7-10-2020 at 01:39


Ferric nitrate or chloride should also work for yellow.
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Sulaiman
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[*] posted on 8-10-2020 at 05:37


I have some iron (II) and iron(III) solutions in partially sealed containers to check stability
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

Pre-printed pantone charts are expensive, so is cobalt chloride, so not cheap for hobbyist references.




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