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Author Topic: How does sunlight remove stains?  (Read 9183 times)

Nadia Ouaked

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How does sunlight remove stains?
« on: 17/08/2009 16:30:02 »
Nadia Ouaked asked the Naked Scientists:
   
Hi,

At a baby birthday party I heard that one of the easiest and least expensive way to remove stains from cloth nappies is to wash them thoroughly and lay them in the sun, stained side up, to dry.

The stain is then supposed to go away.

How does it work?

Thank you for your answer.

Nadia Ouaked

What do you think?


 

Offline techmind

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How does sunlight remove stains?
« Reply #1 on: 17/08/2009 22:46:42 »
I would guess that the thinking is that the the UV component of sunlight (especially midday summer sun) will act as a bleach ... it certainly fades coloured clothes.
Whether it works in practice as you describe, I wouldn't know.
 

Offline Bored chemist

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How does sunlight remove stains?
« Reply #2 on: 18/08/2009 19:24:31 »
Coloured things are only coloured because they absorb light. The light moves the electrons in the molecule into an excited state. The excited molecules are often more reactive; they may decompose or react with oxygen in the air.
If they react then they are likely to be converted to things that are less strongly coloured.
 

Offline Don_1

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How does sunlight remove stains?
« Reply #3 on: 19/08/2009 08:39:31 »
Prolonged exposure to bright sunlight can lead to yellowing of whites.
 

Offline EvilFrog

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How does sunlight remove stains?
« Reply #4 on: 20/08/2009 15:28:12 »
Prolonged exposure to bright sunlight can lead to yellowing of whites.
what react with what will cause the yellowing of whites? can we prevent it? how?
 

Offline Chemistry4me

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How does sunlight remove stains?
« Reply #5 on: 23/08/2009 07:11:57 »
One reason could be this:

Quote
Manufactured white fabrics tend to have an extra coating of fluorescent whitening agents to give fabric a much truer white look. As sun hits this layer of treatment, the materials of the whitening agent can begin to break down. This exposes the true color of the fabric beneath, which looks yellow in comparison to the white coating

http://www.ehow.com/how-does_5164773_do-pillows-turn-yellow.html
 

The Naked Scientists Forum

How does sunlight remove stains?
« Reply #5 on: 23/08/2009 07:11:57 »

 

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