The TCA acid can penetrate quite far. It is considered a medium depth peel due to the fact that with multiple layers, it can reach down into the epidermis and even a bit into the upper Papillary dermis. This is beneficial for many skin issues such as pigmentation, fine lines and scarring, since they tend to run as deep. Regular hydroxy acids can not penetrate past the Stratum Corneum, so they are considered more of a Superficial peel, very superficial peel, or just an Exfoliation.
