De icing fluid, I gather is one of 3 types - Type I, Type II and Type IV. The different types have different hold over times (the time after which the application commenced before which it can no longer be regarded as giving protection).
Type I is 80% glycol diluted with water. The high percentage of glycol means that it is effective as a de icer, but is less viscous than other types so it has a correspondingly reduced hold over time.
Type II is 50% glycol, so not so effective as a de icer, but also contains a thickening agent, which improves its viscosity and so increases its hold over times.
Type IV is similar to type II but contains a more advanced thickening agent for even greater hold overs.
You may recall the colour of the agent that was used on your flight - if so Type I is a clear liquid, Type II is straw coloured and Type IV is green.