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Old 10-05-2016, 07:36 PM   #1
IRENE's Avatar
City: Port Angeles, WA
Country: USA
Vessel Name: Irene
Join Date: Jan 2016
Posts: 863
Apparent Mold in Nonskid - Need Solution Please


We are getting what I believe is mold, growing in our nonskid. This is molded (no pun intended) gelcoat nonskid, and the suspected mold begins looking like black dots. It happened last winter, and was not a problem over the summer. As we get less sun and more moisture, the suspected mold is visible again. I am relatively new to the PNW and I believe many of you have experience I would find useful.

It does not wash away with Zip Wax soap and water. I used Davis FSR last winter, along with a stiff brush, with some success. It seems to grow back fairly rapidly.

I would like to remove it and prevent it if possible. IRENE lives outside on the trailer and gets washed weekly. I do not wish to use a product that will remove the wax from the other surfaces. I am considering trying plain water with a power washer, maybe a car wash to start.

Any and all thoughts and advice are appreciated.

Thank you!


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Old 10-05-2016, 07:51 PM   #2
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City: La Conner, WA
Country: United States
Vessel Name: Imagine
Vessel Model: Farrell 34
Join Date: Oct 2015
Posts: 399
Look for a product called Moldex. Hardware stores, big box etc.

It kills the hyphae that grow into the substrate, bleach can't do that. Neither will a power washer. 10 years experience with mexican mold speaking.

I use it to kill mold in baja after floods. If will kill mexican mold, it ought to work on Port Angeles mold! Chemical warfare.

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Old 10-05-2016, 09:06 PM   #3
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City: Seneca Lake NY
Country: US
Vessel Name: Bacchus
Vessel Model: MS 34 HT Trawler
Join Date: Nov 2014
Posts: 3,896
I've had similar black spots on NonSKid and had the most success with Star Brite Non-skid deck Cleaner w PTFE...which gets good reviews from fellow boaters and some 3rd party testing

I've also found that polishing the NS w/ swirl remover cleans, brightens and makes subsequent cleaning assumprton is that it removes the chalky gelcoat surface and leaves a smoother surface. I've done some areas by hand w/ swirl remover and a non-abrasive (white) scotch brite type pad...I'm considering buying a brush head for my dual action polisher to make this chore a lot easier.

This article confirms that it is probably mold
2008 MS 34 HT Trawler
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Old 10-05-2016, 09:15 PM   #4
IRENE's Avatar
City: Port Angeles, WA
Country: USA
Vessel Name: Irene
Join Date: Jan 2016
Posts: 863

Fantastic, thank you! Your explanation and their website correlates with what I see going on.

I have sent them an email asking for a product recommendation that WILL NOT remove wax from the rest of the boat. Perhaps not possible, but worth asking. They have quite a variety of products. My local hardware carries it too!

Thanks again -

Best Wishes
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Old 10-06-2016, 12:18 PM   #5
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City: DC
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Vessel Name: Carolena II
Vessel Model: Nordic Tug 32/34
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We're in a fresh water environment with very warm, humid summers. Mold or most likley mildew spots in the nonskid is an ongoing problem for us. I've tried a bunch of cleaners, including the starbrite with PTFE, with mixed success. The one I'm using now is the Woodywax boatsoap. It claims on the bottle that it removes mold/mildew spots and it does follow through with regular washing. That said, if we neglect it and it gets really bad, we wind up using Tilex mold and mildew with great success (safe for fiberglass shower surrounds), but it will remove any wax. We then follow up with the Woodywax soap, and finally with a coat of woody wax itself to prevent further stains. YMMV.
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