Patches can be ironed onto cotton , denim , wool , and leather . When using a iron, set it to cotton (up to 350 degrees farenheit) . Place a damp cloth over the patch and iron onto desired fabric or garment , while applying firm pressure for 30 seconds . Allow patch to cool for 5 minutes. Turn fabric over , or garment inside-out , and iron the area behind the patch , applying firm pressure again for another 30 seconds . Allow area to cool for 5 minutes . Patches can also be sewn onto fabric or garments with a single or double stitch by sewing along the border of the patch.