Best solution to get rid of black spots on fiberglass

ericcarr2000

Ensign
Joined
Mar 19, 2010
Messages
903
Ok guys, I have a 1990 sundancer that is in a slip. I noticed the other day that there were little black spots beginning to form on the fiberglass. Does anyone know of a good cleaning solution to get rid of these?
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Black spots on the hull normally means blisters have formed and are now popping open, the black spot is from trace chemicals in the liquid inside the blister.

Oxalic acid will removed black stain, but won't help with the more serious blister issue.
 

ericcarr2000

Ensign
Joined
Mar 19, 2010
Messages
903
Ok will do. Next time I go up to her I'll do just that. The spots aren't any type of black stains, just little tiny black spots on the surface of the fiberglass. I'm assuming some type of a rubbing compound should take care of it?
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Ok will do. Next time I go up to her I'll do just that. The spots aren't any type of black stains, just little tiny black spots on the surface of the fiberglass. I'm assuming some type of a rubbing compound should take care of it?

On what portion of the boat?
 

ondarvr

Supreme Mariner
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Apr 6, 2005
Messages
11,527
I jumped the gun a little on the blister situation then, bilsters are normally below the water line.

In those spots it could be almost anything, mold, polution, spider poop, other bug droppings, etc. We would need a much better description or pics to identify them.
 

64osby

Admiral
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Jul 28, 2009
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6,799
The black stuff sounds like something that I get on my siding and gutters. They are less then 1/8" in size and hard. A real bugger to clean off.
 

kramerpage

Chief Petty Officer
Joined
Jul 26, 2010
Messages
447
My experience has been those spots are from spiders living within or around the craft. My marina sprays twice a year but they seem to make a home. I use Wesley's bleach white to remove if that is indeed what it is. The spots I speak of are a "pin head" or two in size.
 

ericcarr2000

Ensign
Joined
Mar 19, 2010
Messages
903
Thanks woodonglass, I just got done ordering some on eBay. Looks like it should do the trick. I'll let you all know how it works out after I receive it.. Thanks again.
 
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