Wikipedia contains a good summary of the different types of fluid:
Type I fluids have a low viscosity, and are considered "unthickened". They provide only short term protection because they
quickly flow off surfaces after use. They are typically sprayed on hot
(130–180°F, 55-80°C) at high pressure to remove snow, ice, and frost.
Usually they are dyed orange to aid in identification and application.
Type II fluids are pseudoplastic, which means they contain a polymeric thickening agent to prevent their immediate flow off
aircraft surfaces. Typically the fluid film will remain in place until
the aircraft attains 100 knots or so (almost 200 km/h), at which point
the viscosity breaks down due to shear stress. The high speeds
required for viscosity breakdown means that this type of fluid is
useful only for larger aircraft. The use of type II fluids is
diminishing in favour of type IV. Type II fluids are generally light
yellow in color.
Type III fluids can be thought of as a compromise between type I and type II fluids. They are intended for use on slower aircraft, with
a rotation speed of less than 100 knots. Type III fluids are generally
light yellow in color.
Type IV fluids meet the same AMS standards as type II fluids, but they provide a longer holdover time. They are typically dyed green to
aid in the application of a consistent layer of fluid.
The main component of deicing fluid is usually propylene glycol or
ethylene glycol. Other ingredients vary depending on the manufacturer,
but the exact composition of a particular brand of fluid is generally
held as confidential proprietary information.
Call ahead to the airport to see what kind of deice/anti-ice fluid that they have because each one is different.
Every year, the FAA publishes tables which include information about how long the various deice fluids will provide protection under various weather conditions. Here is an example table:
For this particular fluid (ABAX ECOWING AD-49 Type IV) we can lookup a specific example such as:
- -10 Degrees Celcius
- 75% fluid and 25% water
- Light Snow
This shows that the fluid will provide protection for 1:40 to 2:05. If you are delayed longer than that, you will need to deice again. Since every part of the aircraft needs to be protected, the timing starts when they first start spraying the aircraft. Note that other types of fluid (particularly Type I fluids) have much shorter holdover times than this, so be careful and make sure that you check!