How to remove fine scratches from windscreen?

[XC60KEV]

Thanks for replies guys re washer nozzles.

I don't have a clue about windchill and freezers but appreciate should re-phrase the question a wee bit....

...Do the washer nozzles work when its freezing?

[mu71rd]

mine started off frozen on a trip back from the cotswolds, and 2 hours later were still frozen. very annoying.

only after 2 hours sat on the drive with a warm engine bay had they unfrozen - time for some stronger concentrates of anti-freeze i think!

[mu71rd]

Originally Posted by Matteus XC60

No, I don't think so. The blast freezer freezes things more quickly, but cannot make them colder than the actual temperature of the air it 'blasts' so to speak. So, in the case of the original post, if the nozzles are warmer than the outside temperature at the start of the drive, then the windchill from driving will cause them to cool more quickly, but will not make them colder then the prevailing air temperature. Stick your head out of the window however, and your face will certainly feel colder!

Just to continue the geeky theme, I just wanted to add that i don't think that point is entirely correct, and that in effect Kev is right.

The wind chill factor increases the speed with which an object loses heat, be it human or not.

In the case of washer nozzles, this is relevant. When driving, they will warm up because they are near the engine bay. But with wind chill factor they will lose that heat quicker than if there was no wind chill. There will be a balance point below which the nozzles lose heat faster than they receive it from the engine, which would cause them to stay frozen on a given journey.

That explains why the nozzles on my car stayed frozen during a 2 hour journey on Sunday, but thawed once the car was stationary on the drive.

geekyness over

[robg]

Originally Posted by mu71rd

Just to continue the geeky theme, I just wanted to add that i don't think that point is entirely correct, and that in effect Kev is right.

The wind chill factor increases the speed with which an object loses heat, be it human or not.

In the case of washer nozzles, this is relevant. When driving, they will warm up because they are near the engine bay. But with wind chill factor they will lose that heat quicker than if there was no wind chill. There will be a balance point below which the nozzles lose heat faster than they receive it from the engine, which would cause them to stay frozen on a given journey.

That explains why the nozzles on my car stayed frozen during a 2 hour journey on Sunday, but thawed once the car was stationary on the drive.

geekyness over

mu71rd, what you have said here is the same as Matteus xc60 said. You are both right. Wind chill will cool it quicker, but cannot make it colder than the wind is.

Anyway, i badly scratched my screen on a peugeot about 15 years ago and it annoyed me for years after. Since then i always squirt (from de-frosted nozzles..)and wipe the screen with the wipers when i park the night before i expect frost, literally clean the screen in the last hundred yards before end of journey. No dirt left on the screen to scratch the glass the next morning.

I have never had a scratched screen since.

Easy in theory, difficult to think ahead sometimes...

Hope this helps others?

[Matteus XC60]

Originally Posted by mu71rd

Just to continue the geeky theme, I just wanted to add that i don't think that point is entirely correct, and that in effect Kev is right.

The wind chill factor increases the speed with which an object loses heat, be it human or not.

In the case of washer nozzles, this is relevant. When driving, they will warm up because they are near the engine bay. But with wind chill factor they will lose that heat quicker than if there was no wind chill. There will be a balance point below which the nozzles lose heat faster than they receive it from the engine, which would cause them to stay frozen on a given journey.

That explains why the nozzles on my car stayed frozen during a 2 hour journey on Sunday, but thawed once the car was stationary on the drive.

geekyness over

What I said was that wind chill cannot make something colder than the prevailing air temperature (but can make a living organism feel like it is colder). I also said that it would chill objects more quickly. So yes, if the prevailing air temperature is below freezing, then I agree that the nozzles will freeze and by travelling they will freeze more quickly and potentially for longer. But whilst windchill might make +5 degrees feel like -5 to you and I, the nozzles will not freeze.

[robg]

My post (can / cannot) typo edited, LOL, miss made my own point.