The patient is interviewed and an exam is completed to gather information on possible causes of their contact dermatitis. Patients may bring in their products from home so the ingredients can be examined and if the patient has a specific product that they are suspicious of or wish to be tested to a patch can be designed using the chemical they bring in. At the conclusion of the visit the test panels are applied to the patients skin, usually on the back. Each panel is made up of an adhesive background with 10 individual chambers containing pure chemicals suspended in petrolatum or aqueous solutions. From this point on the test area cannot be washed until the conclusion of the test.