The Cronak process is a conventional chromate conversion coating process developed in 1933 by The New Jersey Zinc Company. It involves immersing a zinc or zinc-plated article for 5 to 15 seconds in a chromate solution, typically prepared from sodium dichromate and sulfuric acid. The process was patented in the United States on March 24, 1936 with USPTO number 2,035,380.
- Gregory Zhang, Xiaoge (1996). Corrosion and Electrochemistry of Zinc. Springer Verlag Gmbh. pp. 16, 17. ISBN 978-1-4757-9877-7. Retrieved 12 December 2014.
- US patent 2035380, Ernest John Wilhelm, "Method of coating zinc or cadmium base metals", published 1936-03-24, issued 1936-03-24, assigned to The New Jersey Zinc Company