Welcome! I've learned to wash my fabrics after I had a run in (pun intended!) with reds and blacks. Before the dye magnets were available, I used vinegar with cold water to set the colors and didn't have any trouble. The problem I found with the sheets, are fabrics that continue to bleed after the first wash, espcially if hot water gets used. Once you've given the quilt to someone, you don't know how they'll wash the item. Ergo, I make sure that fabric won't bleed before I send it off.