Diffusion laws.

[Capitol]

For those intellectually challenged and those who should remember their physics, the fundamental equation for the diffusion coefficient is :-

D = kT/G where K is the Boltzman constant, T is the absolute temperature and G is the resistance to motion. I commend a reading of Physical Chemistry by JN Bronsted for better understanding..

For the simple explanation, how many of you make tea, even iced tea, with cold water? I guess none, this is a simple example of the way in which the diffusion laws work. Hotter = greater diffusion. Within certain boundary conditions in washing machines, hotter = cleaner faster.

Lesson over.

[Tim Streater]

In all fluids, is this?

I never make iced tea, what a revolting concept.

As others have pointed out or implied, turbulence wins here.

[Bob Minchin]

Please Sir!

The change in washing temperatures say from 303K to 333K (30C doubling to 60C)won't make huge difference in D Presumably G also falls with temperature in most cases leading to some sort of exponential rise of D with temperature increasing the effect of temperature rise?

[The Natural Philosopher]

What has ANY of this got to do with washing?

In particular with the difference between water that came into the machine cold and was subsequently heated, and water that came into the machine hot? When the majority of the time is spent with the water hot tumbling the clothes about?

You really are intellectually challenged if you think it makes the slightest bit of difference.

I need to coin a name for people like you, who jump in with a perfectly correct but completely irrelevant piece of information in order to try to appear clever, and end up appearing stupid instead. The Smeaton Troll*

*After Stanshall's Reg Smeaton.

[Andrew Gabriel]

Washing at low temperature uses enzymes in the detergent. There are several with slightly different best operating temperatures, but they are all destroyed above around 40C, so for these to work, the wash needs to start below 40C. It can go on to get hotter after the enzyme cleaning action. Some dirt will clean off better at higher temperatures, but equally other dirt won't because the higher temperature changes it chemically to something that won't clean off.

Diffusion is probably not a significant factor as much as heat supplying energy to break molecule chains and speed up endothermic reactions. However, it also supplies energy to polymerise some dirt and make it harder to wash off, so that needs to be washed off in the earlier part of the wash before the water is hot.

This is partly why most machines are cold-fill only now.

[Dave Plowman (News)]

And more shrinkage too.

I'd guess you never do the washing in your house.

[Cursitor Doom]

You guess wrong:

[Albert Zweistein]

Far too simplistic to mean much I'm afraid.

[The Natural Philosopher]

Its a class of argument akin to 'climate change science'

[Chris Hogg]

Iced tea, when well made, i.e. in the Southern States of USA, is delicious and refreshing, particularly nice in the heat and high humidity they get down there.

[Chris Hogg]

Fick off!

:-)

[Brian-Gaff]

Does this not depend on the design onf the cleaning medium you add, ie powder, liquid or whatever though?. One of the selling points of certain liquids is that they are supposed to mix better at lower temperatres, are they, shock horror, not being entirely truthful here? :-)

Brian

[The Natural Philosopher]

No, that poster just dragged a massive red herring across the thread. Ignore what he says

[Tim Streater]

I'll believe you, thousands wouldn't, as my old man used to say.

[dennis]

Diffusion is a very small effect compared to stirring which is what a washing machine does.

[John Jackson]

Not necessarily. I use normal detergent and only ever use cold water. Works fine.

[Chris French]

In message , John Jackson writes

I think Andrew meant that the enzymes require lower temps, not that non bio detergents don't work at that temp

[Davey]

It's still an affront to society. Tea is hot, period.

[Fredxxx]

A bigger affront to society is intolerance to others' tastes.

[harry]

Drivel. The biggest affront to society is tolerating the intolerable as toleration leads to ever more excess. Eg Islam.

Only lefty bastards practice toleration. It make them feel smug and superior. They love to posture in front of any audience.