Chroma test strips

[FredRydr]

I understand why water migrates up the fibers of a paper towel, but I don't understand why the dyes separate the way they do on Chrissy's wet paper towels. Is there something in the paper that causes the mix of dyes in ink to separate?

Fred

e.g.: Chrissy's chroma test strip of Diamine Saddle Brown:

http://fpgeeks.com/forum/attachment.php?attachmentid=29609&d=1485370800

[KrazyIvan]

The long explanation: http://www.explainthatstuff.com/chromatography.html

[FredRydr]

Thank you!

Fred

[Chrissy]

Thanks for the link. I had never read that before. :)

[Sailor Kenshin]

Not every ink will 'chroma' into a rainbow. My favorites are those that do.

[BrynRedbeard]

Just my guess but I think that inks with a single pigment or dye would not chroma. Inks where the color is scheduled by mixing dyes or pigments would.

Cheers

[Chrissy]

Just my guess but I think that inks with a single pigment or dye would not chroma. Inks where the color is scheduled by mixing dyes or pigments would.

Cheers
Yes they do. They just produce one colour on the test strip. That's how I know they only contain one dye.

[Chrissy]

Here's where I found out about chroma testing.

Chroma testing (http://pbskids.org/zoom/activities/sci/papertowelchromatogr.html)

[ppmiranda]

This is a very enlightening thread. I always wondered how these chroma tests work.

[Chemyst]

Not every ink will 'chroma' into a rainbow. My favorites are those that do.

You might also try changing the mobile phase from water to something like acetone or alcohol. The different polarity will change the migration of different components and may result in different color patterns altogether.


Just my guess but I think that inks with a single pigment or dye would not chroma. Inks where the color is scheduled by mixing dyes or pigments would.


Pigments are immobile on paper chromatography. Since they don't dissolve in the mobile phase, they are not transported with it up the column.

[titrisol]

Paper chromatography is fun, I havent looked for chromatography paper as I had a stash of old paper that was going to be discarded at the university and I kept.
For most soluble inks water, or water-ethanol, or water-isopropanol mixes are good enough
For the more permanent inks, Water-ethanol and iso-propanol (rubbing alcohol) makes for good chromatograms.

It can also help make nice "tye dye" style shirts using sharpies! LOL

[titrisol]

I was playing with this last night with my daughters.... using paper towels (my chromatography paper is MIA)
Most ink behaved as expected, but the one that blew my mind was Diamine's Jet Black It has 6 colors including a bright green.
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