Bottom Paint Makers face Irgarol Shortage


Bottom Paint Makers face Irgarol Shortage

Antifouling paint manufacturers are reporting that Irgarol, a pesticide commonly used as a boosting agent in antifouling paints, is in short supply in the United States. Based on what we have learned, it seems likely that the supply of paints containing this pesticide will be exhausted sometime this year. For some makers, their supply will run out as early as this spring.

Bottom paints containing Irgarol are usually marketed as having a boosting agent that enhances the paints protection against algae, soft growth, or slime, and are priced around $30 higher than similar formulas without Irgarol. Interluxs Micron Extra with Biolux, Pettits slime-resistant SR formulas such as Trinidad SR and Ultima SR-40 (and SR-60), and Blue Waters Copper Pro SCX paints such as Copper Pro SCX67 (hard and ablative) are examples of these paints. In our most recent test involving 55 different paints, nearly one-quarter of them contained Irgarol.

Given the shortage, it is possible that bottom paints formerly touted as having slime-resistant formulas will no longer contain Irgarol. It is still not clear how manufacturers will handle the naming and labeling of these products, but in the past, some manufacturers have significantly changed the formulas of paints without changing the names.

Buyers will have to look at the active ingredients to determine whether a paint touted as slime resistant actually contains Irgarol 1051. As required by the U.S. Environmental Protection Agency, Irgarol 1051 is prominently listed in the active ingredients, usually under its systematic name, N-Cyclopropyl-N-(2-methyl-2-propanyl)-6-(methylsulfanyl)-1,3,5-triazine-2,4-diamine. It usually represents about two percent of the paint by volume.

After several years of testing paints containing Irgarol, our own findings indicate that paints with Irgarol will be of most value to seasonal sailors who paint their hull every year but do not regularly clean it. Irgarol has not been shown to extend the active life of antifouling paints in our tests, and weve had a hard time discerning any enhanced slime resistance in Irgarol-boosted paints after six months in the water. (Note again the comments in my recent blog post regarding the differences between our panel testing and actual results on a hull.)

If you are a long-term, warm-water cruiser who cleans his or her hull, we don’t see any real benefit of paying extra for a slime resistant paint containing Irgarol. The fact that some paints touted as slime-resistant might not even contain Irgarol offers one more reason to stick with conventional copper paints this season, or those boosted with zinc pyrithione, ZnP, also called zinc omadine. Zinc is a naturally occurring mineral and is found in a wide range of healthcare products, including sunscreen and diaper cream. The paints containing zinc are often among the top-rated antifoulants in our test

Irgarol is in the family of triazines, and is one of several boosting agents introduced by manufacturers after tributyltin, a suspected endocrine inhibitor found to be harmful to marine life, was phased out. We were told that the reason for the Irgarol shortage is that the manufacturer, BASF, has not taken the necessary steps to gain EPA approval to continue manufacturing in the U.S. Recent studies have called into question Irgarols safety, and it is unclear when the manufacturer will meet the EPA requirements.

Practical Sailor has been independently testing and reporting on marine products for serious sailors for more than 45 years. Supported entirely by subscribers, Practical Sailor accepts no advertising or any form of compensation from manufacturers whose products we test. Testing is carried out by a team of experts from a wide range of fields including marine electronics, marine safety, marine surveying, sailboat rigging, sailmaking, engineering, ocean sailing, sailboat racing, and sailboat construction and design. This diversity of expertise allows us to carry out in-depth, objective evaluation of virtually every product available to serious sailors. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser with more than three decades of experience as a marine writer, photographer, boat captain, and product tester. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.


  1. Has practical sailor done a ( or any one else) legitimate study of adding cayenne pepper to an ablative bottom paint against the same bottom paint without cayenne pepper. Like to put this matter to bed . Thanks

  2. Old Bay seasoning in the paint it’ll help it keep the crabs away because they know we use it to cook just like the cayenne pepper and the muscles don’t like to be in hot pepper eitherAlan S

    I think if you put Old Bay seasoning in the paint it’ll help it keep the crabs away because they know we use it to cook just like the cayenne pepper and the muscles don’t like to be in hot pepper either


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