defrosting windscreen
 

I've always been told that you shouldn't use water as it could crack the
glass. Is this true or one of those old wives' tales?

defrosting windscreen
 

You shouldn't use hot water as this will re-freeze faster than cold
water would(and for all of those people who don't believe me, go and
try it).

Just buy some de-icer - or get a car with a heated windscreen

defrosting windscreen
 

"Grumps" wrote in message
...
I've always been told that you shouldn't use water as it could crack
the glass. Is this true or one of those old wives' tales?
I used this method for years, on conventional and bonded windscreens,
and had no problem using hot-tap-temperature water.

I now stand a 40 year old Ducal Aristocrat domestic fan heater (2.25kW)
inside the car for a quarter of an hour or so on a frosty morning -
thaws the windows, and makes the whole thing less unpleasant to get
into. Costs about 2p on Economy 7.


--
Kevin Poole
**Use current month and year to reply (e.g. )***
Car Transport by Tiltbed Trailer - based near Derby

defrosting windscreen
 

On Thu, 12 Jan 2006 08:23:54 -0000, "Grumps"
wrote:

I've always been told that you shouldn't use water as it could crack the
glass. Is this true or one of those old wives' tales?

I always use warm to hot water (not boiling!) and it always does the
trick. Sometimes you have to apply twice to remove all the frost if
its really bad but it works well and you are not squirting horrible
chemicals all over the place.



Remove antispam and add 670 after bra to email

http://www.no2id.org/

defrosting windscreen
 

On Thu, 12 Jan 2006 08:23:54 -0000, "Grumps"
wrote:

| I've always been told that you shouldn't use water as it could crack the
| glass. Is this true or one of those old wives' tales?

There is a standard way of breaking glass bottles cleanly to form a
?glass? using boiling water. So boiling water definitely breaks glass.
--
Dave Fawthrop dave hyphenologist co uk
17,000 free e-books at Project Gutenberg! http://www.gutenberg.net
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/

defrosting windscreen
 

Dave Fawthrop wrote:
On Thu, 12 Jan 2006 08:23:54 -0000, "Grumps"
wrote:

| I've always been told that you shouldn't use water as it could crack the
| glass. Is this true or one of those old wives' tales?

There is a standard way of breaking glass bottles cleanly to form a
?glass? using boiling water. So boiling water definitely breaks glass.

It's all about temperature differences surely, and changing temperatures
quickly; the reason glass breaks is because it expands when it gets hot,
and if that happens too quickly the glass won't warm up evenly,
resulting in breakage.

Consider the following:

1. Take a wine glass out of the cupboard and fill with boiling water -
it's unlikely to break.

2. Put it in a pan of cold water and bring to the boil on the cooker -
again, not likely to break.

3. Put the empty glass in the freezer for a while, then remove and fill
with boiling water - it'll almost certainly break, due to the rapidity
of the large temperature change.

David

defrosting windscreen
 

"Grumps" wrote in message
...
I've always been told that you shouldn't use water as it could crack the
glass. Is this true or one of those old wives' tales?

I wouldn't risk it. I've never seen why people just don't clear the
windscreen as I do - with a credit card..

defrosting windscreen
 

"Grumps" wrote in message
...
I've always been told that you shouldn't use water as it could crack the
glass. Is this true or one of those old wives' tales?


Yep jug of cold water, add a little hot till you can feel a change in the
temp of the water (i.e. warm not hot)
poor this over the screen - no probs in 20 years !!!
--
Vass

defrosting windscreen
 

Alan wrote:
You shouldn't use hot water as this will re-freeze faster than cold
water would(and for all of those people who don't believe me, go and
try it).

Have a think about the physics of that for a minute.

Hot water will never re-freeze faster than cold water. To freeze water
much reach 0deg. Water which is 10 deg will freeze faster than water
which is 40 deg given the same surface temperature of the windscreen etc.

When using warm/mildly hot water, you may get it re-freezing sometimes
simply because the energy stored within the hot water applied isn't
sufficient to raise the window temp above 0deg, but it will have raised
it a little. Just keep putting more and more warm water on it until the
temp has increased above 0deg and it stops freezing.

D

defrosting windscreen
 

Alan wrote:

You shouldn't use hot water as this will re-freeze faster than cold
water would(and for all of those people who don't believe me, go and
try it).

some of the hot water will evaporate, the amount which is left will
re-freeze in the same time as a similar amount of cold water.

defrosting windscreen
 

On Thu, 12 Jan 2006 09:07:48 GMT, Lobster
wrote:

| Dave Fawthrop wrote:
| On Thu, 12 Jan 2006 08:23:54 -0000, "Grumps"
| wrote:
|
| | I've always been told that you shouldn't use water as it could crack the
| | glass. Is this true or one of those old wives' tales?
|
| There is a standard way of breaking glass bottles cleanly to form a
| ?glass? using boiling water. So boiling water definitely breaks glass.
|
| It's all about temperature differences surely, and changing temperatures
| quickly; the reason glass breaks is because it expands when it gets hot,
| and if that happens too quickly the glass won't warm up evenly,
| resulting in breakage.
|
| Consider the following:
|
| 1. Take a wine glass out of the cupboard and fill with boiling water -
| it's unlikely to break.
|
| 2. Put it in a pan of cold water and bring to the boil on the cooker -
| again, not likely to break.
|
| 3. Put the empty glass in the freezer for a while, then remove and fill
| with boiling water - it'll almost certainly break, due to the rapidity
| of the large temperature change.

True but pouring boiling water onto a windscreen will produce a large
temperature difference, and so may crack the windscreen.
--
Dave Fawthrop dave hyphenologist co uk
17,000 free e-books at Project Gutenberg! http://www.gutenberg.net
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/

defrosting windscreen
 

Following up to Paul Andrews

I wouldn't risk it. I've never seen why people just don't clear the
windscreen as I do - with a credit card..

or a £1.50 scraper you keep in the door pocket? That way you
remove H20 from the car, rather than adding it,which surely isnt
what you want. Especially on the opening windows, which should
also be clear before you consider driving. IMHO in very cold
weather its not safe to drive until the engine has warmed up
enough to maintain clear unmisted windows. So out of bed 10
minutes early, start the engine and get scraping! YKIMS!
--
Mike Reid
Walk-eat-photos UK "http://www.fellwalk.co.uk" -- you can email us@ this site
Walk-eat-photos Spain "http://www.fell-walker.co.uk" -- dontuse@ all, it's a spamtrap

defrosting windscreen
 

On Thu, 12 Jan 2006 08:23:54 -0000, "Grumps"
wrote:

I've always been told that you shouldn't use water as it could crack the
glass. Is this true or one of those old wives' tales?

Use warm water with a dash of dishwasher rise aid.

defrosting windscreen
 

The Reid wrote:
Following up to Paul Andrews
I wouldn't risk it. [hot water to defrost windscreen] I've never
seen why people just don't clear thewindscreen as I do - with a
credit card..

or a £1.50 scraper you keep in the door pocket?

69p from Lidl.

The disadvantage with these scrapers is that they have straight
edges, .: aren't so good for windscreens. Credit cards, and so
on, are much better as long as the ice isn't too thick.

A pail of water from the cold tap is quick and efficient.

defrosting windscreen
 

Autolycus wrote in message
...

"Grumps" wrote in message
...
I've always been told that you shouldn't use water as it could crack
the glass. Is this true or one of those old wives' tales?

I used this method for years, on conventional and bonded windscreens,
and had no problem using hot-tap-temperature water.

Me too, never had a problem, water about 60 deg C here. Kids start the
car, put on the heater and air-con for five minutes or so, do the hot
water thing and put the wipers on, I go out at the last minute and drive
to school. Easy peasy :-)

Incidentally I hired a Ford Focus in England recently with a heated
windscreen, which I didn't need to use whilst I was there. Most of the
time it was fine but once I started seeing the little lines I couldn't
stop seeing them, if you know what I mean. Good idea but I wouldn't buy
one unless they made the whole thing less visible.
--
Holly, in France
Holiday Home in Dordogne, now with pool!
http://la-plaine.chez-alice.fr/index.htm

defrosting windscreen
 

Dave Fawthrop wrote:
There is a standard way of breaking glass bottles cleanly to form a
?glass? using boiling water. So boiling water definitely breaks
glass.

It's the thermal shock that breaks the glass, not the temperature. One
part expands much faster than another.

Glass is made at something like 2000 centigrade after all.

Dave

defrosting windscreen
 

Dave Fawthrop wrote:
| 3. Put the empty glass in the freezer for a while, then remove and fill
| with boiling water - it'll almost certainly break, due to the rapidity
| of the large temperature change.

True but pouring boiling water onto a windscreen will produce a large
temperature difference, and so may crack the windscreen.

Windscreens aren't made out of the same glass as glasses are.
I've used hot water for years and a friend uses boiled water out of a
kettle.
You're not immersing a frozen windscreen into a tub of boiling water -
you're pouring a thin layer of hot water onto a cold windscreen so
there's not huge energy transfers going on. If you put your hand into a
bowl of very hot water you'll get scalded but if you splash a bit of
that same water on you it probably won't do any damage at all.
Some say that the water will freeze over almost immediately in which
case you need to use more water. Some say to use rinse aid so the
water rolls off before it can freeze but I've never needed to.
I fill a jug up from the tap, go outside, pour it on the screen and
other windows, jump in the car then I'm off. All while next door have
the car with the engine running and are scraping away at the windows
with a scraper.

defrosting windscreen
 

tarquinlinbin wrote:
On Thu, 12 Jan 2006 08:23:54 -0000, "Grumps"
wrote:

I've always been told that you shouldn't use water as it could crack
the glass. Is this true or one of those old wives' tales?

I always use warm to hot water (not boiling!) and it always does the
trick. Sometimes you have to apply twice to remove all the frost if
its really bad but it works well and you are not squirting horrible
chemicals all over the place.

agreed.

I've done this for years with several cars and never broke or cracked a screen.

defrosting windscreen
 

On 12 Jan 2006 02:54:42 -0800, wrote:


Windscreens aren't made out of the same glass as glasses are.
I've used hot water for years and a friend uses boiled water out of a
kettle.
You're not immersing a frozen windscreen into a tub of boiling water -
you're pouring a thin layer of hot water onto a cold windscreen so
there's not huge energy transfers going on.

Yeah, I recon that the layer of ice takes most of the thermal shock
away.

Anyhoo, if the hot water is prone to re-freezing it can't be heating
the glass very rapidly, can it?

sponix

defrosting windscreen
 

On Thu, 12 Jan 2006 10:51:22 GMT, "david lang"
wrote:

| Dave Fawthrop wrote:
| There is a standard way of breaking glass bottles cleanly to form a
| ?glass? using boiling water. So boiling water definitely breaks
| glass.
|
| It's the thermal shock that breaks the glass, not the temperature. One
| part expands much faster than another.
|
| Glass is made at something like 2000 centigrade after all

Glass is brittle as everyone who has broken a glass doing the washing up
knows. Expand one bit in relation to another and it goes ping.
--
Dave Fawthrop dave hyphenologist co uk
17,000 free e-books at Project Gutenberg! http://www.gutenberg.net
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/

defrosting windscreen
 

In article ,
"Holly, in France" writes:
Incidentally I hired a Ford Focus in England recently with a heated
windscreen, which I didn't need to use whilst I was there. Most of the
time it was fine but once I started seeing the little lines I couldn't
stop seeing them, if you know what I mean. Good idea but I wouldn't buy
one unless they made the whole thing less visible.

I have a Ford/Triplex electric windscreen, and they are brilliant.
I easily get several minutes head-start driving off from the
car park at work, verses colleagues with scrapers and deicer,
who still ended up driving off with some degree of ice on
their windscreens. It's also much faster for demisting than the
hot air vents when the engine's cold. It was one of the key
reasons I went for that car (although the electric windscreen was
an optional extra at the time), having seen one in use on a
friend's car. I don't notice the wires unless I specifically look
for them -- when driving you are focused at or near infinity, not
18" in front of your eyes. However, at 8 years old, some areas of
it don't work anymore.

--
Andrew Gabriel

defrosting windscreen
 

defrosting windscreen
 

Grumps wrote:

I've always been told that you shouldn't use water as it could crack the
glass. Is this true or one of those old wives' tales?

I've been using tepid water for years. When the water has got a bit
warmer from the hot tap, the worst I have heard is a creek from the seals.

HTH

Dave

defrosting windscreen
 

Grumps wrote:

I've always been told that you shouldn't use water as it could crack the
glass. Is this true or one of those old wives' tales?

From the replies posted so far, no-one seems to have heard of a
windscreen breaking from the application of water. Might the old
wive's tale have originated in much earlier times, when glass
technology was not what it is today, and screens were more easily
shattered? I've used the water method for thirty-odd years with no
problems.

defrosting windscreen
 

Homer2911 wrote:
Grumps wrote:

I've always been told that you shouldn't use water as it could crack
the glass. Is this true or one of those old wives' tales?

From the replies posted so far, no-one seems to have heard of a
windscreen breaking from the application of water. Might the old
wive's tale have originated in much earlier times, when glass
technology was not what it is today, and screens were more easily
shattered? I've used the water method for thirty-odd years with no
problems.

http://www.bbc.co.uk/weather/feature...snow_rac.shtml

"Do not use warm water as this may cause the windscreen to crack."

defrosting windscreen
 

"Homer2911" wrote in message
oups.com...

Grumps wrote:

I've always been told that you shouldn't use water as it could crack the
glass. Is this true or one of those old wives' tales?

From the replies posted so far, no-one seems to have heard of a
windscreen breaking from the application of water. Might the old
wive's tale have originated in much earlier times, when glass
technology was not what it is today, and screens were more easily
shattered? I've used the water method for thirty-odd years with no
problems.

Tempered glass windscreens were created by heat treating the glass, so I
would say that they were even less likely to shatter than modern laminated
screens. I suspect it is that people knew that you should not plunge thick
glass into boiling hot washing up water and assumed that the same would
apply to any glass with any volume of heated water, whatever the
temperature. I used water from the hot tap for many years, before getting a
garage, and, like you, never had a problem.

Colin Bignell

defrosting windscreen
 

Grumps wrote:

Homer2911 wrote:
Grumps wrote:

I've always been told that you shouldn't use water as it could crack
the glass. Is this true or one of those old wives' tales?

From the replies posted so far, no-one seems to have heard of a
windscreen breaking from the application of water. Might the old
wive's tale have originated in much earlier times, when glass
technology was not what it is today, and screens were more easily
shattered? I've used the water method for thirty-odd years with no
problems.

http://www.bbc.co.uk/weather/feature...snow_rac.shtml

"Do not use warm water as this may cause the windscreen to crack."

So the RAC isn't above perpetuating old wive's tales then?

defrosting windscreen
 

Andrew Gabriel wrote:
when driving you are focused at or near infinity, not
18" in front of your eyes.

I find on a pool car at work that if I look down at the speedo then back
up at the road my eyes briefly focus on the wires. I wouldn't buy one.

Chris


--
Spamtrap in use
To email replace 127.0.0.1 with blueyonder dot co dot uk

defrosting windscreen
 

Chris Hodges wrote:

Andrew Gabriel wrote:
when driving you are focused at or near infinity, not
18" in front of your eyes.

I find on a pool car at work that if I look down at the speedo then back
up at the road my eyes briefly focus on the wires. I wouldn't buy one.

I had a similar experience, but now I own a Mondeo, don't notice
the wires at all, and certainly would not swap for an unheated
screen.

Chris
--
Chris J Dixon Nottingham UK


Have dancing shoes, will ceilidh.

defrosting windscreen
 

On Thu, 12 Jan 2006 08:35:42 -0000, Autolycus wrote:

"Grumps" wrote in message
...
I've always been told that you shouldn't use water as it could crack
the glass. Is this true or one of those old wives' tales?
I used this method for years, on conventional and bonded windscreens,
and had no problem using hot-tap-temperature water.

I use boilng kettles sometimes.

chief danger is it may freeze again.


I now stand a 40 year old Ducal Aristocrat domestic fan heater (2.25kW)
inside the car for a quarter of an hour or so on a frosty morning -
thaws the windows, and makes the whole thing less unpleasant to get
into. Costs about 2p on Economy 7.

defrosting windscreen
 

David Hearn wrote:
Alan wrote:

You shouldn't use hot water as this will re-freeze faster than cold
water would(and for all of those people who don't believe me, go and
try it).


Have a think about the physics of that for a minute.

Hot water will never re-freeze faster than cold water.

Physics is more complex than you seem to think. Google for "Mpemba effect".

Douglas de Lacey

defrosting windscreen
 

defrosting windscreen
 

Following up to david lang

Interesting benefit I hadn't expected when I gravelled my drive - gravel is
completely immune to icy patches that make you fall on your arse
unexpectedly.

I have found my blocks over concrete are quite good, I assume
because it takes an age for them to get cold. SWMBO-Mums crazy
pazing only needs damp to make it an ice rink.
On gravel, we have it at the back and had to bring range cooker
in that way, try moving a heavy cooker on a delivery mans
"skateboard" over gravel :-(
--
Mike Reid
Walk-eat-photos UK "http://www.fellwalk.co.uk" -- you can email us@ this site
Walk-eat-photos Spain "http://www.fell-walker.co.uk" -- dontuse@ all, it's a spamtrap

defrosting windscreen
 

On Thu, 12 Jan 2006 10:15:02 +0000, The Reid wrote:

I've never seen why people just don't clear the windscreen as I do
- with a credit card..

Best scraper about, nice an flexable follows the curve of the glass
well.

That way you remove H20 from the car, rather than adding it,which
surely isnt what you want.

Quite. Those using even warm water obviously don't have decent frosts.
I've had the aerosol squirty stuff freeze on the windscreen before now
and frequently go very thick. Scraping cars with -10C air temp and
probably another 5 or 10 lower on the glass is not my idea of fun even
with gloves on.

So out of bed 10 minutes early, start the engine and get scraping!

Naw, out a few minutes early start the engine press demist button,
note change in engine note as the front and rear heated screens come
on. Couple of minutes later just wipe the melted frost off with the
wipers. B-)

--
Cheers
Dave. pam is missing e-mail

defrosting windscreen
 

erm, no it won't - think about the chemistry first.

Ice is a lattice structure (like a diamond), and it takes energy for
the molecules to move into the lattice. In hot water, the molecules
are moving rapidly, and can therefore form the lattice quicker than
cold molecules which have very little energy.

That's why I said go and try it if you don't believe me - 2 containers
of water in a freezer (one hot, one cold), the hot one will freeze
faster than the cold one.

I've done it many times.

defrosting windscreen
 

Alan wrote:
erm, no it won't - think about the chemistry first.

Ice is a lattice structure (like a diamond), and it takes energy for
the molecules to move into the lattice. In hot water, the molecules
are moving rapidly, and can therefore form the lattice quicker than
cold molecules which have very little energy.

That's why I said go and try it if you don't believe me - 2 containers
of water in a freezer (one hot, one cold), the hot one will freeze
faster than the cold one.

I've done it many times.

Hey - that's physics, not chemistry.
Another explanation is that the hot container melts any frost and is in
much better contact with the freezer's cooling tubes. The cold
container is sitting on a nice insulating blanket so can't lose heat as
quickly. It's also been suggested that the hot container has
convection currents and is more turbulent by the time it's cooled down
to the same temperature as the cold one was, and from there freezes
more quickly.

--
LSR

defrosting windscreen
 

The message .com
from "Alan" contains these words:

Ice is a lattice structure (like a diamond), and it takes energy for
the molecules to move into the lattice. In hot water, the molecules
are moving rapidly, and can therefore form the lattice quicker than
cold molecules which have very little energy.

Are you suggesting that ice forms at temperatures above zero degrees
Centigrade?

--
Roger Chapman

defrosting windscreen
 

"Roger" wrote in message
k...
The message .com
from "Alan" contains these words:

Ice is a lattice structure (like a diamond), and it takes energy for
the molecules to move into the lattice. In hot water, the molecules
are moving rapidly, and can therefore form the lattice quicker than
cold molecules which have very little energy.

Are you suggesting that ice forms at temperatures above zero degrees
Centigrade?

I don't think he is, but water at zero degrees does not have to be ice, it
can still be liquid.
In fact super cooled water is liquid at negative degrees.
Put a solid into the liquid and the resulting current provides enough energy
for the molecules to lattice up
and form ice.

Also water does strange things between zero and four degrees centigrade,
explains why my fish pond doesn't freeze solid.

Dave

defrosting windscreen
 

The message
from "someone here" contains these words:

Ice is a lattice structure (like a diamond), and it takes energy for
the molecules to move into the lattice. In hot water, the molecules
are moving rapidly, and can therefore form the lattice quicker than
cold molecules which have very little energy.

Are you suggesting that ice forms at temperatures above zero degrees
Centigrade?

I don't think he is, but water at zero degrees does not have to be ice, it
can still be liquid.
In fact super cooled water is liquid at negative degrees.
Put a solid into the liquid and the resulting current provides enough energy
for the molecules to lattice up
and form ice.

But if the water is hot first it has to cool. Once cooled its molecules
have lost that rapidity of motion the previous poster refers to above.

Also water does strange things between zero and four degrees centigrade,
explains why my fish pond doesn't freeze solid.

AIUI water is at its most dense at 4C so ice forms on the surface.
However given a severe enough frost you fish pond would freeze solid.

--
Roger Chapman

defrosting windscreen
 

In message , Roger
writes
The message
from "someone here" contains these words:

Ice is a lattice structure (like a diamond), and it takes energy for
the molecules to move into the lattice. In hot water, the molecules
are moving rapidly, and can therefore form the lattice quicker than
cold molecules which have very little energy.

Are you suggesting that ice forms at temperatures above zero degrees
Centigrade?

I don't think he is, but water at zero degrees does not have to be ice, it
can still be liquid.
In fact super cooled water is liquid at negative degrees.
Put a solid into the liquid and the resulting current provides enough energy
for the molecules to lattice up
and form ice.

But if the water is hot first it has to cool. Once cooled its molecules
have lost that rapidity of motion the previous poster refers to above.

Also water does strange things between zero and four degrees centigrade,
explains why my fish pond doesn't freeze solid.

AIUI water is at its most dense at 4C so ice forms on the surface.
However given a severe enough frost you fish pond would freeze solid.

FSVO severe

like ... very (well, as we brits might define it)

--
geoff