On 22/12/2017 21:01, DJC wrote:
On 22/12/17 14:34, ARW wrote:

De-icer these days only seems to work when it's above minus 1 deg
regardless of what it says on the tin.



During the recent cold spell I spayed de-icer on the windscreen, which
promptly froze making things worse. I wasn't below -2C.



That isn't surprising.
You melt the ice and that takes heat to do so.
That mostly comes from the glass so it gets colder and any remaining
water/fluid will freeze. If there is a lot of ice it will get so cold
the insides will condense and freeze.

Its simple physics and its the reason I don't have any de-icer but I do
have a scraper.