Non Skid; Black Spots

[Richard19068]

View attachment 215664

Above is an enlarged section of the OP's photo. Notice the relative uniform shape of the dark areas and how the white gelcoat fades away to the dark area. Also notice the white streaks in some of the dark area. The dark areas are all in the valleys.

Thus far, no one has reported success at removing these kinds of dark spots, because it is not dirt, it not mold, is the fiberglass under the gelcoat. Gelcoat is sprayed into the mold when the deck is built and it is not an entirely uniform thickness, thus, some areas under the nonskid are a little thinner or thicker than other areas. After 30 years of scrubbing, the thin layers wear out. The gelcoat is thinnest under the valleys in the non-skid.

There is no easy fix, all will require standing the non-skid smooth and adding new nonskid. There are options that range from gluing on a rubberized non skid, a one part fix like Kiwi Grip, painting and adding grit like Soft Sand, or using gelcoat and Gibco Flex mold. The other option is just learning to live with it as it is.

Wish there was a more optimistic solution. One thing for certain, more aggressive scrubbing will only make it worse.

To me, that that appears to be the obvious problem.
Do not use an abrasive or acidic cleaner. That will just serve to wear down the gel coat. If it was mold or dirt or something else like that a stiff brush, some non abrasive cleaner and elbow grease would do the trick.

There is no easy fix, all will require standing the non-skid smooth and adding new nonskid. There are options that range from gluing on a rubberized non skid, a one part fix like Kiwi Grip, painting and adding grit like Soft Sand, or using gelcoat and Gibco Flex mold. The other option is just learning to live with it as it is.

This implies that painting would require sanding off the non-skid. Is there a way to paint over the existing non-skid without removing it? Maybe using an abrasive cleaner, some wax remover / degreaser and then a couple of relatively thin coats of appropriate paint and some small grit?

 

[dlochner]

This implies that painting would require sanding off the non-skid. Is there a way to paint over the existing non-skid without removing it? Maybe using an abrasive cleaner, some wax remover / degreaser and then a couple of relatively thin coats of appropriate paint and some small grit?

Hmmmm. I think it depends on how worn the nonskid is and the conditions the boat will be sailed in. I don't think just adding NS grit to paint on the existing NS will won't do much, it might even make it worse if the grit slid down into the valleys.

If there is sufficient texture to the NS, then a couple of coats of a polyurethane paint might work and improve the texture. This may be adequate most sailing, however, for crossing oceans I'd want a more aggressive NS.

 

[Richard19068]

... it might even make it worse if the grit slid down into the valleys.

Good point. Hadn't thought about that.

My question was more about being able to get the recessed part of the existing non-skid cleaned or roughed up enough for the new paint to stick.

Thanks

 

[Scott B]

Thanks, I’ll give it a try!

I had black spots on my non-skid for years and tried a ton of methods. Finally emailed Shurhold and she got back to me with pics of her fishing boat in FLA and spotless diamond non-skid. She reccomended the stiff deck brush although I could only get medium at the time. I iniatally used their power cord bruch ( stiff bristles ) on my hands and knees one afternoon ( 4 beer job ) and came out amazingly clean and now keep it up with the medium deck brush and boat soap.