The foil process is a little different from your typical screen printing. Foil works by screen printing an adhesive to a garment or substrate and then curing (sending down the dryer). Once the garment is cured the foil is then added by heat pressing it to the garment. Once the garment has been heat pressed the foil will only adhere to where there was adhesive. The remaining foiled is peeled away. Foil screen printing is the most delicate finish in the industry. It is very important to pay close attention to washing instructions to preserve the foil for a long time.  Make sure to turn any foil garments inside out in the wash. Wash only with cold water and make sure your dryer settings are on delicate. Air drying will preserve the foil for even longer.