Submitted on November 7, 2005 by Jim Mulholland

Question: Hello -

I have a North Genoa made of NorDac that has developed a few mildew spots and I plan on doing some year end maintenance cleaning. I have read conflicting reports about using bleach on nylon sails. I'm not sure how NorDac/Dacron would be affected. So I am going to list my arsenal of cleaners for treating stained cloths and ask which ones are safe to use on my sails. Please tell me which ones can be used on NorDac and include maximum application time limits if any apply. I am particularly interested in your response to using OxyClean since I think that will do the trick.

Goop, Gojo (without pumice) or other types of lanolin soaps. Good for
dirt, oil and grease. Apply with brush and elbow grease then rinse.

Murphy's Oil Soap (vegetable oil soap). Good for dirt, oil and grease.
Apply with brush and elbow grease then rinse.

Fels Naptha bar soap. Good for dirt, oil, grease, and stains. Apply
with brush and elbow grease then rinse.

Household bleach/Clorox mixed 1/30 bleach water (as per one of your
previous posts to clean Norlam). Good for mildew, mold, and organic
stains. Apply, brush it in, soak, brush, repeat as needed, then rinse
well. Is there a time limit on how long the bleach water can be left on
the sail cloth? How strong can the mix be: would 1/10 strength be OK
for short periods?

OxiClean (sodium percarbonate) Mixed 2 scoops per gallon of hot water.
Good for mildew, mold, and organic stains. Apply, brush it in, soak,
brush, repeat as needed, then rinse well. Any time limit for application?

And finally can Lysol All Purpose Cleaner (n-Alkyl Dimethyl Benzyl
ammonia chlorides) be used on NorDac? Obviously mixing Clorox
(chlorine) with Lysol (ammonia) would be a bad thing.

Thanks
- Jim Mulholland

Answer: Dear Mr. Mulholland,

The sort of strong cleaners that kill and remove mildew can also damage many materials, so they should not be used indiscriminately.

Specifically, bleach should not be used on aramids (Kevlar, Twaron) or nylon. It's like Kryptonite to Superman.

On the other hand, bleach is an ideal treatment on almost any other sail material. It has no adverse affect on polyester (Dacron), Spectra or Dyneema, or the film and adhesive used in laminates. It is effective in very weak solution (i.e. 1 gallon Clorox to 30 gallons of water, 1 to 10 or 15 if you're impatient) if given a few days of soak time. It has the advantage of both killing the mildew and bleaching out the stain. We have done exhaustive, full-strength, long term soak tests with Clorox on all sorts of materials so we're confident about this recommendation.

Lysol is a bit milder, also kills mildew and should be safe on any sailcloth. It does not do nearly as good a job of removing imbedded stains as bleach.

Another often overlooked mildew remover is clean salt water. There have been a number of reports of sails coming up spotless after being hung overboard for a few days in clean deepwater anchorages, and we have seen it happen in limited lab testing. Salt water, of course, is quite safe to use on any sail. Rinse well afterwards.

We don't have good data or experience for the safety or effectiveness of other products you mention. I would differentiate between solvents that act as degreasers and spot removers, and actual anti-fungal agents. The primary goal is to kill the mildew. Stain removal is secondary, and won't happen as long as the mildew colony remains alive. Once the mildew is dead by whatever means, normal weathering will tend to fade the stains over time.

Also, scrubbing or any other form of abrasion is not effective with mildew. On a microscopic level, the mildew buries itself inside yarn bundles and other crevices in the material. It can't be reached from the top, where the brush's bristles are, without removing parts of the yarn and so forth to get at it. Obviously this would be counterproductive.

This is why immersion, or soaking, is the only effective way to get at mildew. Ideally, the whole sail should be put into a big tank of solution, though I'm sure some effect can be achieved by spraying or sponging solution directly on a spot, probably several times over several days. Stronger concentrations can work slightly faster but depending on severity, whatever is used still seems to take days rather than hours to achieve a good result.

I'm sorry we don't have good information on all the items you have considered, but I hope this helps a little.

Best regards,
Bill Bergantz
North Cloth

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