Originally Posted by
The Bartender
As far as i know, the use of Type IV has been abandoned in Scandinavia for this reason...
Yes. SAS and Nordic Aero used type IV fluid when it was introduced for one season, then went back to type II for anticing. They use 50% type I for deicing and 100% type II for anticing.
The biggest problem for the supplier was getting the cold type IV to spread over the wing. It came out in globs, and would not spread to form a thin layer. Type II is much better in this respect, and the holdover times with the latest type II fluids are nearly as good as type IV.
You use the type II cold, as it cannot be pumped neat when hot without breaking down. Using it as anticing means that its temperature is not important.