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Alodine is a trademark of Henkel North America, Iridite is a trademark of Macdermid. They both refer to Mil-C-5541 [link is to spec at TechStreet] approved conversion coatings, but as you can infer from the "1200", there are a number of formulations, tailored to certain operating conditions and you would need to read the data sheets from these manufacturers to see if the application procedure and operating conditions are the same.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

Iridite is a brand name of MacDermid, Inc., with several versions such as Iridite 14-2. Alodine 1200S is a brand from Henkel Technologies. Both products are on the Qualified Products List for both Class 1A & 3 coatings. You can download QPL-81706 [link is to spec at TechStreet] from the DoD’s ASSIST site: http://assist.daps.dla.mil/quicksearch/ Since you seem to be using Iridite’ in the generic sense, it is more important to specify MIL-C-5541E, Class 3 than the brand name. Also, each of these products yields a slightly yellow Class 3 coating. If you need Class 3, Clear, there are products specially formulated as such from these and other companies.

Ken Vlach - Goleta, California

Iridite is a trade name for a whole family of chromate conversion coatings. Alodine 1200S is the trade name for aluminum chromate that meets MIL-C-5541-(?). Iridite 14-2 is the particular trade name for a product that is chromate conversion for aluminum. Assuming you probably mean Iridite 14-2, yes Iridite 14-2 and Alodine 1200 S both apply Class 1 or 3 on MIL-C-5541.

Robert H Probert Robert H Probert Technical Services Garner, NC, USA Editor's note:        Mr. Probert is the    author of Aluminum How-To