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Does Bleach only work in Hot Water?


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#1 mrbc19

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Posted 7 July 2005 - 09:21 PM

I have a question regarding clorox bleach.
The washer I have in my house only has a warm wash, one that is more on the cool side, and my roomate claims that the bleach I purchased will not work properly in a cool water wash. I need the bleach to whiten and remove stains, and I told him that it would still work in a cool wash, but I really have no idea or evidence to prove this. Does anyone know if it will still work the same, or if hot water actually does anything different for the bleach?
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#2 d22k

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Posted 7 July 2005 - 11:01 PM

i couldnt say for sure, but i would imagine that it being hotter would certainly help, im saying that from a physics point of view - More Heat = Molecules More Aggitated -
so assuming heat does not break down the bleach, then i would say heat will certainly help.

However, i see no reason why a warm was would not work...

as for evidence to show him... surely the best way would be to do it and see!?
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#3 EL

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Posted 8 July 2005 - 05:36 AM

I have a question regarding clorox bleach.

I fear that you have to give us the chemical specifics, because Clorox is a trademark not a chemical, and they have a wide range of bleaching liquids and powders.
Some chemicals will decompose in high temperature, others demand it to have any effect. In fact, some bleaching process requires heat decomposition to begin its action, while others demand room temperature and much longer time or stronger mechanical agitation.
As a rule of thumb, do not "waste" the bleach on dirty cloths.
This means that the best way for bleaching is to apply it to clean fabric (less the stains), that is other than persistent stains should be removed first. Hot water wash is not recommended first as this might stabilize some stains on fabric.
The second phase is applicable without drying the fabric, that is the best effect is on washed and wet cloths.
Never add the concentrated bleach directly on the fabric, dilute it first.
Use soft water if possible.
With clean fabric wet, all you need is to make sure that the chemical reaches the stains.
Agitation, agitation, agitation, and then some more agitation. :D
Finally read the temperature requirements of the FABRIC, as some fabrics will be destroyed by heat.
Pure wool fabrics (especially knitted pullovers) could shrink to 50% of the original size. :eek:
Cotton and linen seem to love hot water, and sodium hypochlorite would do just fine.
So it is case by case, did that help?
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#4 YT2095

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Posted 8 July 2005 - 08:18 AM

NaClO usualy at 5% or less
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#5 EL

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Posted 8 July 2005 - 04:47 PM

Yes, with NaClO it is better to use hot water if the fabric allows it.
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#6 Yggdrasil

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Posted 8 July 2005 - 07:02 PM

Heat will generally speed up the rate of a reaction. My guess would be that the hot water speeds up the reaction between the hypochlorite and the stains, so that the stains will have all been bleached out by the time the wash cycle is over. The reaction would still occur in colder water, but it would not proceed as fast and may not completely remove the stain.
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#7 mrbc19

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Posted 8 July 2005 - 09:34 PM

To clarify, the bleach is just the basic clorox bleach, the cheapest one you can get. It is sodium hypochlorite, and not the more expensive "bleach for colors" which my roomate said I had to buy if I wanted it to work. One more thing, I've noticed, that if you wear black pants and get bleach on them while cleaning something, like mopping a floor, it whitens the pants. So does this mean that the whitening or "bleaching" effect of bleach is not effected by temperature?
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#8 EL

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Posted 9 July 2005 - 04:32 AM

One more thing, I've noticed, that if you wear black pants and get bleach on them while cleaning something, like mopping a floor, it whitens the pants. So does this mean that the whitening or "bleaching" effect of bleach is not effected by temperature?


Can you bleach a piece of charcoal into white-carbon; No. :D
It is not only a matter of oxidizing a "colour" dear mrbc19, it must be a stain or a pigmentation.
It is common to use oxidizers because, let's say 85% of fabric stains are plant-pigment sources, such as chlorophyll from grass or tomato ketchup sauce, and dust, which is beside natural oxides could have plenty of carbonates, etc. Sodium hypochlorite is also very effective with fountain-pen-ink stains. However, metallic oxides will hardly be washed by oxidizers if any. Cosmetics is another source of coulours: Check this out <http://pigmento-colo....asp?ID_categ=0 >
Now if you check this out: <http://www.maxpages.com/dyestuffs >
You will notice that dyestuff used for cotton (for example) can be instantly bleached by a direct splash of sodium hypochlorite 5%. That is why it is not recommended to apply any concentrated bleach directly on any dry fabdic.
The effect will be very strong and local only. Read my previous post, please.
Good bleaching demands homogenous distribution of the chemicals.
When the bleach is further diluted in the washing batch, it is inevitable to use some heat (in case of NaClO).
What heat does in this case is not only agitation but also exposing the ions temporarily out of the hydration shells.
When Conc. NaClO is splashed directly the fabric's fibres adsorb the water and expose the ions, hence the reaction proceeds unhidred.
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#9 wle7378

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Posted 9 November 2008 - 11:40 PM

haha it seems as though i was wondering about the same type of thing today. I work in a resturant and i heard a few months back that soaking towels in bleach with HOT water will negatively affect the effectiveness of bleach. I have researched all over the web. and i have found that the agreement via basic chemistry, household experiments, and basic common sense is that yes hot water does take away from the effectiveness of bleach. bleach kills 99.9 % of bacteria, so you do not need to soak your clothes in a HOT water/bleach solution. you should soak your clothes in a cold or room temp water/bleach solution to penetrate the stain, seeing as most types of bleach chemically change the molecules of the stain making them invisible to the human eye (some bleach products actually break apart the bonds in the stain eliminating the "stickiness" the stain has to the fabric. Hot water also causes another type of reaction that leads the bleach product to produce Cl gas. which the smell that is given off when you use bleach and hot water. i also confirmed all of this by testing two containers of towels today. i equally stained towels soak for five hours each. I set the first in cold/room temp water, and the second in hot water. the bucket with the cold water was much more effective in removing stains than the hot water bucket. you want as much bacteria to be removed from the fabric as possible. so my suggestion would be to soak them in cold water and bleach and then wash or rinse them in hot water for the most effective cleaning. :-)
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