Porous hair is more prone to breakage, split ends and other kinds of damage.
Hair that dries quickly tends to be more porous than hair that takes a long time to dry. However, the rate at which hair dries is obviously influenced by external factors, for instance, if it's a hot, sunny day or if your central heating system is set high then your hair will tend to dry faster than if it's cold or if your homes's heating is set low.
To test your hair porosity more specifically do the following:
- Get a glass tumbler.
- Fill it with tap water
- Let the water sit undisturbed for c.30 minutes so that it gets to room temperature.
- Pluck a hair from your head and place it on top of the water in the tumbler.
- Watch the hair to see how it sinks.
Porous hair will start to sink right away; the more porous, the faster the hair sinks. Hair that is not porous will float for a long while before it starts to sink.