Which waving solution is least recommended for porous or damaged hair?

Alkaline waves are least recommended for porous or damaged hair due to their higher pH levels, which can be harsh on fragile hair structures. These waves typically use ammonium thioglycolate as the active ingredient and work by penetrating the hair shaft more effectively, which can be beneficial for normal hair types but problematic for hair that is already weakened or porous.

Porous hair tends to absorb moisture and chemicals more readily, increasing the risk of further damage when subjected to the strong effects of alkaline solutions. Using alkaline waves on such hair can lead to excessive swelling, compromising the integrity and moisture balance of the hair, leading to breakage and overall deterioration.

In contrast, options like acid waves are formulated to have a lower pH, making them milder and more suitable for hair that has been damaged or is porous, as they are less likely to cause further harm.