This test calls for a sample of the material in question to be placed in an airtight container with three coupons of different metals—silver, lead, and copper—that are not touching each other or the sample of the material.  The container is sealed with a small amount of de-ionized water to maintain a high humidity, then heated at 60 degrees Celsius for 28 days. An identical container with three metal coupons acts as a control. If the metal coupons show no signs of corrosion, then the material is deemed suitable to be placed in and around art objects. The Oddy test is not a contact test, but is for testing off-gassing.
Each metal detects a different set of corrosive agents. The silver is for detecting reduced sulfur compounds and carbonyl sulfides. The lead is for detecting organic acids, aldehyde, and acidic gases. The copper is for detecting chloride, oxide, and sulfur compounds.
There are many types of materials testing for other purposes, including chemical testing and physical testing.