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Author Topic: Why is cold water better for cleaning blood from clothes?  (Read 18172 times)

Brian

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Brian asked the Naked Scientists:
   
Growing up, my mother told me that when I get blood on my clothes, I should use cold water right away to get the blood stain out.  Why would cold water work better than hot water to get blood out of clothes?

What do you think?


 

Offline DrChemistry

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Why is cold water better for cleaning blood from clothes?
« Reply #1 on: 19/08/2009 19:51:19 »
Perhaps I can give a very primitive answer, and I surely hope someone can either reject or improve it.

The problem lies in the proteins of your blood. Proteins present have the tendency of reacting to eachother, a lot, and so they clutter up. Therefore they are giving us a hard time to remove. Using hot water will practically give the proteins a thermal bath, and cause them bind more effectively, reducing your chances of removing them. Cold water on the other hand do not boil it, and it should come off if the blood is still fresh, as long as you do not smear it out :)

Edit: Typos, spell check,
« Last Edit: 19/08/2009 19:56:22 by DrChemistry »
 

Offline Don_1

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Why is cold water better for cleaning blood from clothes?
« Reply #2 on: 20/08/2009 07:48:36 »
This applies to anything spilt on your clothes, be it blood, red wine, fruit juice, coffee/tea and so on.

Its a simple case of not virtually 'cooking' the spilt substance. Or as Dr Chem put it, giving it a thermal bath.

In cold water, the stain will disovle. A little bio washing powder will help. An overnight soak usually does the trick.

The coloured fabrics used for clothing etc. will usually start out white, they are then submersed in die which is 'cooked' in by heating the dye solution. This doesn't apply to printed fabrics, of course.

 

Offline Edster

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Why is cold water better for cleaning blood from clothes?
« Reply #3 on: 20/08/2009 20:41:42 »
Most dyes are used with a mordant to "fix" or precipitate them to the fabric, these are normally at low temperature. Some older processes from the dawn of the industrial revolution required elevated temperatures towards boiling water which have been superceded on economic grounds by lower temperature processes

Many synthetics are "dyed" at elevated temperature as the colour is mixed in the molten polymer.

They can be coloured after manufacture but the intensity of the colour achievable is less than when introduced in manufacture.
This also a room temperature or near to process.

( does anyone remember the eyeball searing purple and green and yellow... nylon shirts beloved of asian door to door salesmen in the late 60`s early 70`s? I saw them on market stalls,they came from india or china and a company called Brentford Nylons all over the UK stocked shirts  nearly as loud  with OU lecturer collar shapes).

Blood and other organic componds will bind to natural fabrics and as a  result of length of exposure to air and breakdown of proteins and fats etc ( and  in blood formation of fibrins which bond very well to  fibres as they do to skin when clotting ) usually at 20 C or below there is time to treat the stain whilst it is still water soluble ( with detergent) before it breaks down/ binds too tightly to the cloth fibres. water over about hand comfortable will hasten the breakdown and "fix" the stain, (this applies to red wine too!).

Most bio powders containing enzymes will break  the protein linkages ( that`s  a large part of what enzymes do) and dissolve blood stains completely if left in a bowl of cold water overnight.

 

Offline Mazurka

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Why is cold water better for cleaning blood from clothes?
« Reply #4 on: 24/08/2009 15:21:16 »
Although this has been comprehensively answered, I would add that biological washing powders work better at low temperatures as the enzymes become denatured (cooked) at higher temps.
 

Offline DrChemistry

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Why is cold water better for cleaning blood from clothes?
« Reply #5 on: 24/08/2009 15:56:34 »
Although this has been comprehensively answered, I would add that biological washing powders work better at low temperatures as the enzymes become denatured (cooked) at higher temps.

Reminds me of the TNS show where they were looking for a villain with smelly feet using DNA. One guy said that they had put their tubes in a water bath at 37 degrees for the enzymes to do their work optimally.
 

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Why is cold water better for cleaning blood from clothes?
« Reply #5 on: 24/08/2009 15:56:34 »

 

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