Further browsing the www on this subject, as nothing more useful seems to be possible under the present wx, I came upon

If on arrival you descend with an iced up aeroplane and windshield and cannot see, use the DV window.

Any suggestions as to the meaning of the "DV" window? Dorsal view? Dual visualisation? Direct ventilation?

The full document is at

http : //www .ebzr.be / LinkClick.aspx?fileticket=hEVd4RWiFrU%3d&tabid=40&mid=412

(a few blanks inserted to disable link expansion)

and seems to confirm most of what was said here, including the garden sprayer.

A DV window is a Direct Vision window. Usually something that you can open and so get a view no matter whether the main windows are iced up/shattered. Think the little window flap on the PA28.

That is a helluva temperature. It would melt the windows in a light GA plane.

Re windows, some deiced planes have a little heated window on the front, so the pilot can see "something". It is a poor man's version of the £20k heated glass windscreen :)

With TKS you don't need it. In fact my prop-only TKS does a good enough job on the front window.

Kilfrost have their own webshop which seems to sell it for £110 incl VAT & Delivery for 25ltrs. So while still expensive it's better value, though less easy to handle and store.