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Why Can’t I Spray Algex On Bare Aluminum?


Dave Acton ​asked:

Why do the instructions for ALGEX say (twice) “Do not spray onto bare aluminum.” I thought this product is an aluminum boat cleaner?


For your convenience, I’ve highlighted the hyperlinks. Click on the hyperlink to get more information about the selected product.

Algex is a bio-fouling remover made especially for use on aluminum boats. When used as directed, it will remove algae and leave the aluminum its original silvery finish. Most acid bottom cleaners are designed for fiberglass and will etch the aluminum and turn it white or cause white streaks and spots. Algex can cause the same whiting, streaking problem if allowed to dry on the aluminum. It needs to be kept wet and allowed to work, until it’s rinsed off.

The reason for the cautions is that too often boat owners spray it, willy-nilly, all over the place, not just on the algae and allow it to dry on the bare aluminum which will cause the white streaking and spotting. If that happens, the aluminum can be buffed back to its original finish with Alumabuff, so the damage is not permanent, but that involves extra work and expense.

If you are unable to control the spray, I suggest that you mask off adjacent areas to prevent overspray.

If you need an aluminum cleaner, I suggest that you look a Boat Clean Plus. If you need a brightener to remove dark water stain then try Alumabrite CBX. These products are designed especially for those applications. Algex is a bottom cleaner.

Thanks for your question,
Captain Aurora
Richard Kittar

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