Take your daybed frame into a large workspace with plenty of ventilation, like a garage or patio. Place drop cloths on the floor and over any surrounding furniture.
Apply finish or paint stripper per the can directions. Test the stripper on a small area of the bed near the foot before applying it to a large area.
Let the paint "strip" and lift the paint. The paint will have a crumpled or wrinkled appearance. Allow the frame to dry completely on its own. The finish should set back onto the iron but now have cracks and wrinkles in it, giving it a distressed look.
Gently sand the bed frame with medium-grain sandpaper. Some of the paint may lift, distressing it a bit more. Sand roughly around tops of the posts an and near the feet for a more severely distressed look.
Apply a clear sealant with a brush, following the label directions. Let the bed dry completely, overnight, before moving it back into its room.