Boiling water onto cold windscreen?

Don't use boiling water whatever you do.

It's perfectly ok to use tepid water, just warm to the fingers and it works fine and is the quickest and easiest way IMO.

Andy

Here we go again!!

More than likely, but it doesn't matter. Especially if you're bored with the one you got, and was thinkin of gettin a new one anyway.

I see this being done all the time round here. I have only done it twice, when we had a very severe air frost. Being the sad person that I am I have made a study of frost. The frost on a car is easy to get off if its a ground frost. If we get an air frost the ice becaomes much more crystaline and will not scrape off easily. Often deicer itself goes semi frozen when its air frost.

When you put boiling water on a windscreen it actually goes cold very quickly in the low temperatures we get up here so the risk might be less. I remember in the hosue I used to stay in the water had gone from boiling to frozen by the time it got to the bottom of the windscreen so it just made things worse. I wouldn;t use boiling water now, I use deicer and if it looks like we are getting a bad frost I put cling film on the windscreen the night before.

Well I've used water out the hot tap for years with no problems, it doesn't get the screen anywhere near as warm as Instant defrosting ones.

The best solution is to work from home like wot I do and then you can just leave the car in the feeble sunlight to defrost itself until you really need to drive down to Budgens to buy more whisky. Hic.

I'd agree though. Tepid water is fine but pouring boiling water on a frozen screen is asking for trouble. Putting the bugger in a garage overnight is another cunning ploy.

-- Dave Baker

Don't use boiling water, use warm water, try it on your screen, if it doesn't seem to do anything then try some warmer water, if it starts cracking or steaming then the water is to hot. I leave the car running for 5 mins to warm it up anyway, so a quick go around with the water is all that is needed. Or just leave the car running for 10mins with heaters on full, the internal temp in the car only has to rise a couple of degrees anyway, probably cheaper to use warm water then waste 10mins of petrol though :-)

Chris

In my ignorant youth, I used to do this all the time and never once did it immediately crack the screen.

What it does do though, is create lots of tiny little scratches on your windscreen, that you can't see at all, until you're driving at night and somebody comes the other direction to you, and you are blinded by their headlights glaring in all the minute scratches on your windscreen.

Alex.

The message from WM contains these words:

Don't use boiling water - just hot from the tap is sufficient - and who needs a spare windscreen to test it on? I and many others have been doing it on in-use screens for decades.

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

How?

Where I used to live upto last November, people had their cars on the street and used to start them up in the mornings and then go indoors for half hour or so. Although this practise is totally illegal, we hardly ever saw a plod about the place.

-- the_constructor

saw an interesting programme t'other day. Apparently boiling water freezes much more quickly than warm water. Counter-intuitive, but water molecules in boiling water are further apart (and hence cool down more quickly) than in warm water.

Or something Nick

The message from "NickD" contains these words:

There are situations under which that can be true but it's by no means universal. In most situtations where hot water freezes sooner it's because it convects fast and exposes hot water at the surface continuously. Cold water tends to skin over with ice quickly which dramatically slows further cooling.

In the case of pouring it down a windscreen these conditions are irrelevant.

You must have bloody hard water in your area ;-)

-- Stuart

In news:Xns975660B95D9716AD265@204.153.244.170, WM wrote something quite bizarre, possibly in an effort to confuddle the world. It went like so;

When I worked in car hire on freezing nights we used to look for Vectras with stonechips in the screen. If you put the heater on full demist with the fan on full it'd invariably crack the screen right across from the stonechip to the nearest edge of the 'screen. We did about 20 one winter. Which was nice as we didn't have to drive the things until a new screen was fitted.

"Alex, Boosbeck." wrote in news: snipped-for-privacy@4ax.com:

I work at a glass factory. Samples are tested for thermal shock by dipping them in 20degC water for a while then immediately placing them into 65degc water. This proves that they are satisfactory (for a bottle, at least). Pouring 90degC water onto your 0degC windscreen is another matter, although I would imagine that windscreens are rather more tough than bottles. I always stick to tepid to be on the safe side.

IME, all screens pick up very light scratches with age. I've always put it down to the dirt that collects on the wipers(?).

you would have thought so, but I remember my dad doing it when I was a kid.

Personally I find it quicker to scrape the screen than wait for the kettle to boil.

Plus in really cold weather, the water tends to refreeze quite quickly too.

Must be well-off to afford all that extra petrol (I noticed it had a big effect on the fuel computer readings on my Saab, and haven't done it since). Not to mention the effect on the environment.

Bollocks. I used to use boiling water all the time, and I never had a cracked windscreen.