Cortec Corporation's  M-236 additive is a liquid corrosion inhibitor for copper, aluminum and steel. It is especially designed to prevent corrosion of copper in power transformers during extreme heat.

M-236 is an easy-to-use liquid that readily mixes with a variety of oils and other solvent blends. It can also be added to transformer oils during original manufacture and shipment, or added to power transformer oils in use. M-236 immediately provides corrosion protection for copper, yellow metals, aluminum, and ferrous metals.

M-236 additive is especially effective against the residual sulfur and the build-up of sulfur in transformer oils, which cause severe corrosion of copper. Oils containing 1% of M-236 passed the ASTMD1748 copper strip tarnish test, even when the oil contained up to 100 ppm of sulfur. Further, M-236 does not change the electrical properties of oil. When tested in transformer oils at 250-500 ppm, M-236 did not adversely affect the dielectrical breakdown voltage.

M-236 protects oils in different corrosive environments including humidity, H₂S, SO₂ and elevated temperatures. It helps power transformers currently in the field and those just coming online to meet new higher standards of performance. With distribution systems in more than 80 countries, Cortec M-236 is available to companies with multi-national requirements.