Izal was used on all shore establishments in the Navy, even had the pussers mark on it.

On submarines we were blessed with the soft stuff, Izal would have just bunged up the beautifully named 'slop, drain & sewage' tanks, shortened to ***t tanks.

We would all be prepared to hold our noses when we heard the pipe 'periscope depth, standby to blow ***t'

The tanks were blown using high pressure air to sea. What did you do with the HP air in the tanks afterwards......you vented it back into the boat. Nasty niffs all round.