Tapa, or bark cloth, is a non-woven felted material prepared from the inner bark of certain plants. Oil was sometimes applied to make tapa waterproof and more flexible. Oiled tapa objects usually become severely degraded. Gas chromatographic - mass spectrometric analysis was used to identify the oil as kukui nut oil in six of the seven samples. A consideration of drying oil chemistry suggests that it is the highly unsaturated oil which has oxidized and caused the degradation. Degraded oil contains acid products bound to the oil matrix. Paper conservation methods which work for un-oiled tapa are not suitable for oiled tapa. Conservation of oiled tapa should consist mostly of proper storage consisting of low temperature, moderate relative humidity, and good physical support.