Boiling water onto cold windscreen?

Yep, it goes blue when you add soap!

Most of us have moved on and installed a hot tap. ;-)

Andy

I don't know, I'm not a physicist. I'd imagine it does it exactly the same way that everybody else tells you pouring boiling water onto a frozen windscreen does! It's just the cracks are minute cracks on the surface of the glass, rather that great big cracks that you can see.

Unecessarily stupid IMO but feel free.

Andy

Well go and pour boiling water in a thick pint glass, and see what happens. It will smash. You've just been lucky, that's all

That's not what was originally posted though, so the fact you've been pouring 'lukewarm' water on the windscreen is irrelevant, try boiling water as some silly person first suggested then over time see the effects.

But that's not a windscreen it it? How many pint glasses are laminated?

and have it attached to a combi boiler for instant hot water ;-)

-- Stuart

Mmm. But in my house it's still quicker to scrape the screen than wait for the water to run hot.

I _am_ a physicist and I don't agree with what you're saying.

Well you were right ! :-)

Andy

as lots of others have said, use warm water from the tap I find the best place to pour it is form the top of the screen and just at the top pouring it anywhere else just tends to leave big lumps of ice everywhere once the water has defrosted the ice and run to the bottom, the second lot of warm water should be trickled over the wipers, this makes the rubber softer and more pliable so it can effectively clean the screen of the water that's going to start getting cold in a hurry

mind you,I drive a ford so I get hot screens all the time and when I drive the merc, I can let it run for 2 minutes to get it stonkingly hot and boil away any on screen icicles :)

The message from "Pete M" contains these words:

Astras seemed to do that rather readily, too. Wonder if it's a GM thing.

The message from "Alex, Boosbeck." contains these words:

Given the way toughened glass works I'd seriously doubt that. I would expect it to be more likely that screens just get scratched with age. At

IM*E* nothing bad happened.

How kind. Thankfully, those days are behind me; I choose to live somewhere where it doesn't get cold.

The message from "Taylor" contains these words:

You seem happy to ignore the experience of many people who have done just that. So far not a single person has claimed to have bust a screen doing it, though many have claimed to have had as near to boiling as is practicable without using an extension lead.

I can't believe this. More agitated (increased Brownian movement), yes. Further apart, no. Even *if* they were, how would the increased average distance between water molecules bring about an increase in the rate of diminishing agitation? The answer has to be in the "something"? :)

So does my

Ooops

Move along now, nothing to see here

In an earlier thread on the same subject, Chris Street wrote: "I did it once to my Metro, first winter I had it. Used to use handhot water transported in a kettle after that till I got a car with a heated screen". And he wrote again: "Yup, it propgated from an existing stone chip and spread across the screen as the surface heated and belled out".