Mildew on epoxy

Merrily

Merrily

Administrator
A used boat that I recently bought has some epoxy repairs on the hull. It was fine when I bought it, but now mildew is forming on the epoxy. I chisled it off last week, but it's come back. Before I start attacking it with random chemicals, does anyone have advice? And once I get it stopped, will gelcoat be the thing to keep it from coming back?

Merrily
 
Merrily said:
A used boat that I recently bought has some epoxy repairs on the hull. It was fine when I bought it, but now mildew is forming on the epoxy. I chisled it off last week, but it's come back. Before I start attacking it with random chemicals, does anyone have advice? And once I get it stopped, will gelcoat be the thing to keep it from coming back?

Merrily
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The definitive solution to mildew is to wet it with a strong bleach solution -- like a cup of bleach in a quart of water, and to let the bleach solution stand for 15 minutes or so. This strength will put holes in your clothes and is probably pretty hard on any lines or rubber it touches, so watch where it slops. I've used it on fiberglass boats before without any obvious bad effect, but that's just one data point.

If the mildew is coming back, it means the surface is trapping water and whatever nutrients the mildew needs -- if it were me, after the bleach then I'd let the boat dry in the sun, and then wetsand the area until shiny, and then polish with tef-brite, in the hopes that this left the surface slick enough that it would stay dry.
 
Basically, I would go along with the previous message. Dilute one or two teaspoons of bleach in a cup of water. Put on some kitchen gloves and use a Q-tip, old toothbrush or small sponge (I don't know how big the area of concern is) to wet the mildewed area and let it sit for 15 min or so (your boat has to be in the right position, so it won't all run off). Keep the bleach away from everything else with a rag. Rinse with lots of water (four cups or more).
Now you need to focus on why you got the mildew in the first place. Fungi need high humidity to grow and that spot must have been wet at some point in time. Try to keep it dry after you are done sailing. Or perhaps your repair didn't quite seal the wound; if true there is work to do.....
 
macwas16 said:
I find it easy to put the diluted water and bleach in a spray bottle and squirt it on. Works nicely.
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OK, I'm not so patient, I wiped straight bleach on it, chisled it out, wiped more bleach on, then set it out in the sun. It is sparkly white. I did not rinse and I have to leave town tomorrow. Am I going to have a mess when I come back?

Merrily
 
Merrily said:
OK, I'm not so patient, I wiped straight bleach on it, chisled it out, wiped more bleach on, then set it out in the sun. It is sparkly white. I did not rinse and I have to leave town tomorrow. Am I going to have a mess when I come back?

Merrily
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You're probably fine. Some organic materials are very resistant to attack by bleach (such as, obviously, the plastic they use to make bleach bottles). Others less so (such as, the poly / cotton blend in a T shirt I blew holes in last summer). In air/sun, the bleach dissipates to some degree -- that's why you have to keep adding chlorine to a pool all the time. I'll bet you'll be fine. If it were me, I'd try to hit it once with a hose or dump a bucket of water over it before I left in the morning, just to get rid of the worst of the excess leftover.
 
Chris123 said:
You're probably fine. Some organic materials are very resistant to attack by bleach (such as, obviously, the plastic they use to make bleach bottles). Others less so (such as, the poly / cotton blend in a T shirt I blew holes in last summer). In air/sun, the bleach dissipates to some degree -- that's why you have to keep adding chlorine to a pool all the time. I'll bet you'll be fine. If it were me, I'd try to hit it once with a hose or dump a bucket of water over it before I left in the morning, just to get rid of the worst of the excess leftover.
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I stumbled out to the garage last night and wiped the area down. I had only dabbed bleach on the affected area. There wasn't any bleach smell at all so I think it must have already evaporated. Thanks for the advice, and I'll check it when I get back. I just don't want the epoxy weakened by mildew or bleach, I guess.

Merrily
 
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