Bill, your barrels look very nice. No I don't use the FC for rusting. It's used to bring out the pattern, just like barrels. The difference is, with hardend steel it comes out much easier than mild steel. I'd like to know why everyone only leaves the barrels in for 5 seconds? In my experience 30 seconds, or even a minute doesn't hurt. Maybe I'm doing it backwards. I etch befote rusting. I see where people are rusting , then etching. I'll have to re-read the copy of Dr. Gaddys instructions. Paul