I've been using it as a preservative for RC prints and in place of Photo-Flo for film. Ctein recommends it for RC prints. I have had RC prints that have "silvered out" in the past before I started using Sistan, but those were also different papers from today's RC papers. We won't know for 15 years or so whether it's really effective, but reports suggest that it's worth a try. I usually print anything I intend to frame on fiber based paper, though.