Things You'll Need
Instructions
Lay the flat sheet out on the floor, with the decorative side facing down.
Center the crib mattress over the flat sheet, with the top of the mattress facing down.
Resize the flat sheet to fit the crib mattress. Fold the flat sheet up and over the mattress as if you are wrapping a gift. First, fold the sheet edges on the long sides of the mattress in at a diagonal on each side, making a triangular shape. Pull the tip of the triangle up and over the bottom of the mattress, which is facing up, and pin in place.
Cut away any excessive fabric that reaches past 4 inches over the edges of the mattress. Remove the sheet from the mattress and hem the edges of the sheet with a sewing machine to prevent the sheet from fraying. Fold the sheet edge in 1/2 inch, fold another 1/2 inch and sew the folded edge. Repeat on all sides of the sheet.
Secure the sheet to each corner of the mattress using a short upholstery twist-pin. Wrap the sheet around the mattress as if you were wrapping a gift. Push the pins into each corner of the mattress and turn clockwise to secure.
Turn the mattress over and test your work by pressing down on each corner with your hands, putting your weight into it to make sure that the upholstery pins are short enough to not poke your hands.
Place the covered mattress into the crib with the pins facing down.