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Author Topic: How does a stain remover work?  (Read 6317 times)

faith Liebenberg-Cohen

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How does a stain remover work?
« on: 17/12/2008 20:43:48 »
faith Liebenberg-Cohen asked the Naked Scientists:

What is the chemistry of stain removal? How does a stain remover work?

What do you think?


 

Offline chris

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How does a stain remover work?
« Reply #1 on: 18/12/2008 04:14:33 »
Most of them are powerful soaps I think; I think there are limits as to how chemically fierce these substances can be as otherwise they would decolourise everything, not just remove the stain.

Chris
 

lyner

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How does a stain remover work?
« Reply #2 on: 18/12/2008 11:03:54 »
The secret is first to identify what the stain is. Then you can often choose a solvent /soap  which will take away the stain without removing the original colour. Some stains can be dealt with with a mild bleach or by smart 'thinking chemistry' - e.g. salt on blood stains works a treat because the sodium displaces the iron in the haemoglobin which removes the colour.
It helps if you use the correct treatment first because the wrong treatment can 'fix' the stain and make it harder to remove; you risk getting a large 'water mark' which can be more annoying than the original small spot of stain.

I have used 'stain devils' in the past - with varying degrees of success. They come in a range of types, in an attempt to be 'stain specific'. The Lab Tech at my School swears by some of them.
« Last Edit: 18/12/2008 11:06:18 by sophiecentaur »
 

Offline Bored chemist

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How does a stain remover work?
« Reply #3 on: 18/12/2008 19:14:39 »
"salt on blood stains works a treat because the sodium displaces the iron in the haemoglobin which removes the colour. "
Nice hypothesis but not chemically plausible. There's more sodium in blood than there is iron.

Salt on a bloodstain may do a useful job of soaking it up and it may denature the proteins before they get a chance to clot  which might help too.
 

lyner

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How does a stain remover work?
« Reply #4 on: 19/12/2008 07:53:08 »
Oh well.
But it also takes out the colour. I took that as being a chemical reaction. What happens then? It really doesn't appear just to dilute the stain.
 

Offline chris

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How does a stain remover work?
« Reply #5 on: 19/12/2008 08:42:30 »
I agree about the haemoglobin - the sodium ion concentration in blood and extracellular fluid is quite high (130mMol) - and the Fe2+ in haemoglobin is tightly bound inside a porphyrin ring at the centre of the protein. It's therefore unlikely to be iron that's responsible. More likely is that the sodium ions electrically saturate certain parts of the protein, making it less sticky (i.e. denaturing it as suggested above).

The dark stain cause by blood, incidentally, is because once the haemoglobin escapes from the regulated environment of a red blood cell it oxidises to methaemoglobin (Fe3+), hence the dark brown / black colour.

Chris
 

Offline enrikm

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How does a stain remover work?
« Reply #6 on: 03/11/2010 06:02:04 »
This is taken from eHow.com:

The first, and most common, way stain removers work is by simply dissolving the stain with either a solvent or surfactant.

 

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How does a stain remover work?
« Reply #6 on: 03/11/2010 06:02:04 »

 

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