I got a phone call one time while a print was in a tray of HCA. When I came back 30 minutes later, it had lost at least one stop of density, if not more.
Try it on a print sometime. You will be shocked. The thing to keep in mind is that if it bleaches noticeably at 30 minutes, there undoubtedly will be some harder-to-see bleaching that occurs at shorter times than this, but it is all a matter of degree.
Any clearing regimen using HCA (or muriatic) should use the absolute minimum time it takes to get rid of the residual ferric, and no more.
Originally Posted by Jorge