Use of Opti-Seal as a drying aid is a recent discovery. With the help of our dedicated enthusiasts, Optimum continues to find new and unique ways to use our products. As for protection, if you mean durability, my guess is you'll get less longevity when used as a drying aid. It stands to reason you're using less product and diluting it this way, as opposed to applying it as a stand alone process. I use Opti-Seal (or it's sister Hyper Seal) in every wash, so I can't speak to durability.