English: This illustration depicts mechanism of degradation of thermoset polymer (plastic) by galvanic action first published in the literature in 1990. When carbon fiber reinforced polymer (CFRP) is in contact with an active metal such as aluminum or iron, and in contact with salt water, a galvanic circuit, or battery will be created. Carbon fiber in the CFRP is the cathode. It has positive charge (+). The metal, for example aluminum, is the anode. It has negative charge (-). Electrons will flow from the metal to the CFRP. As a result, strong hydroxide ions (OH-) will be generated at the CFRP with Ph of about 12 or 13. This is a type of crevice corrosion where the polymer disappears, leaving bare carbon fibers. This has implications for aircraft design to protect the polyimide CFRP for maximum safety.