hot water

Why is it that using hot water seems to clean things better? Have you noticed that when you used hot water to clean a stain out of a white t-shirt or a gravy spill off of a carpet it worked so much better than using cold water.

Well, after doing some research online regarding the effectiveness of hot water versus cold water cleaning the answer quite simple.

hot water cleaning

The Science: The ‘heat’ (energy) in the water excites the components of soil and oils so they can be lifted up easier using something abrasive.

In other words, hot water loosens up soil and oil so that they can be removed easily as you wipe your shirt clean.

Here is why! According to “Ask A Scientist” from the US Department of Energy:

“Heat almost always makes cleaning more aggressive, in any setting.

I can think of three common behaviors that contribute to this:
1) increased reaction rates – (kinetics) heat speeds up all reactions, even those as humble as water wetting it’s way along the interface between some slime and the fiber of your clothing.
2) increased dissolving abilities – (due to entropy) even without soap, small amounts of some greases will dissolve in water. In hot water, the amount that will dissolve can be ten times higher.
3) melting – some greases are low-melting waxes, and being melted makes it easier for the soapy water to penetrate, detach, and surround them. Even things that are not quite melted at least get softer.”

Clearly, you can get great results from using cold water, in fact, some washing machines advises people to use cold water when washing dark colors because colors might bleed more and stain other clothes if you use hot water.

Update: The hot water also acts as catalyst when used with cleaning chemicals (think carpet cleaners and the dry cleaners). Essentially the same theory, the energy it takes to make the hot water ‘hot’ gets transferred to the cleaning agent and helps removes soil and stains.