Porosity - Hair which absorbs and retains moisture has good or acceptable porosity.
Varying degrees of hair porosity result when:
•Hair is longer and thus older than shorter hair
•Hair is exposed to harsh environmental elements
•Hair is regularly styled with heat implements or chemicals
Over-porous hair is often caused by excessive heat styling (blow drying hot irons, hot rollers), bleaching, coloring, or other chemicals such as Thermal Reconditioning, BKT, chemicals straighteners, relaxers and permanent waves.
When hair is over porous it may feel sticky, slimy or tacky when wet and brittle, rough and scratchy when dry.
Porosity needs to be considered when selecting any type of chemical retexturizing (TR, Relaxing, BKT) and hair coloring products.
Hair porosity can determine formulation mixtures and overall processing times.
When hair is weakened or in poor condition, it's advisable to treat it first to restore porosity. This will actually ensure the best possible TR, BKT and hair color results.
Different Hair Areas To Test
To accurately test hair for porosity, use three different areas: along the front hairline, right in front of ears, and near the crown.
Grasp small strands of dry hair and comb smoothly. Hold the ends firmly with the thumb and index finger of one hand and slide the fingers of the other hand from the ends towards the scalp. If the fingers do not slide easily, or if the hair ruffles up as your fingers slide down the stand, the hair is porous.
The more ruffles formed, the more porous is the hair. The less ruffles formed, the less porous is the hair. If the fingers slide easily and no ruffles are formed, the cuticle layer lays close to the hair shaft. This type of hair is least porous, is most resistant and will require a longer processing time with applying any type of chemical treatments.