Dreaded Black Mold

[shelldrake]

I have an Old Town 50 Lb Model that I re-canvassed 15 years ago. Hull was not oiled, but sealed with thinned varnish. I used Rollin's treated canvas and filler, and dark blue Kirby's paint. Our canoes are stored under a lean-to roof, out of the elements. The 50 pounder is plagued with recurring black mold on the paint surface. We use a bleach and soap solution to remove it, but it returns with a vengeance. I'm guessing that the mold colony is established within the canvas. What I can't figure out is why it is a problem only on this boat. There are two others stored under the lean-to that were re-canvassed with the same material. They get dirty, but not moldy.

Thoughts? I'm guessing the remedy is a new canvas.

 

[Michael Grace]

What is the difference between these canoes? Is the paint different? If mold can colonize one it should be able to colonize all, so something must be different between them, whether in the process of sealing the hull, canvassing and filling, painting, or storage location. In any case, if the mold washes off, perhaps just wash it periodically. Replacing the canvas, filling, and painting again only to find the mold returning again would be very frustrating. It sounds as though the canoe can be cleaned and paddled just fine as is. Replacing the canvas seems very costly in time and effort as an experiment (maybe or maybe not successful) to see if it solves what may currently be only a cosmetic problem.

 

[shelldrake]

Oh, it paddles just fine, but it pisses me off that the mold reappears. The only difference between this one and the other boats are canvas weight and Kirby color. The 50 Lb is 12 wt and the other two are 10 wt I believe. 50 lb is dark blue. Others are red and light green. Thinking about it, I recall that I even lightly sanded and re-painted the 50 lb (same color) a few years ago.

A mystery I guess.

 

[Michael Grace]

I've seen the same thing - some canoes seem to be more prone. Similarly, I don't know why.

Because the varnished interior doesn't have the same problem I've wondered if applying a coat or two of varnish over the paint might help.

 

[Dan Lindberg]

Maybe the #12 canvas didn't get adequate mildicide treatment?

And to date, when I apply filler, I mix in a packet of mildicide that's sold in the 'home" stores to reduce mold on paint in bathrooms.

 

[shelldrake]

Could be Dan. "The dose makes the poison"!

I'll try adding extra mildewcide next time.

 

[MGC]

I own a Morris that had this problem during the years I stored it under outside cover.
After I cleaned and repainted it I began storing it indoors. The problem has not returned.

 

[Dave Wermuth]

I'll just throw this out there. The color is different, right? I wonder if the color and the UV light are factors. Perhaps the UV is not able to kill mold in this color just for the way it reflects/absorbs UV light./? And also, is the canoe always on the canoe rack in the same spot? Perhaps there is less air circulation in that spot and mold can grow? Maybe mix up some mildewcide and rub it on?

 

[shelldrake]

I'll just throw this out there. The color is different, right? I wonder if the color and the UV light are factors. Perhaps the UV is not able to kill mold in this color just for the way it reflects/absorbs UV light./? And also, is the canoe always on the canoe rack in the same spot? Perhaps there is less air circulation in that spot and mold can grow? Maybe mix up some mildewcide and rub it on?

UV difference? Could be. I think it's always been in the same spot. When we wash the mess off, we always use about a 10% bleach solution with the soap. Maybe I should prep it and paint it the same color as one of the other canoes. That would be an interesting experiment.

 

[Dave Wermuth]

A different color and a different resting spot are two variables. Try changing the bunk spot first?

 

[shelldrake]

I'll ty that. Thanks

 

[MGC]

The Morris I had problems with is dark blue...a pettit paint if I can remember that far back.

 

[shelldrake]

Hmmm. This one is dark blue Kirby's. I've got some light green Kirby's left over from another boat. I think I'll give the 50 pounder a new look.

I actually used it today to take my grandson fishing. Fish didn't mind the mold.....

 

[Gary]

Sorry I don't mean to hijack this thread but I am interested in knowing more about Dan's filler additive? I have always treated the canvas with a product containing Zinc Naphthenate but hate the smell and drying time interruption. Plus it's getting harder to find here in Canada.

Dan do you use this as the only means of protecting for mold/mildew or do you do something to the canvas as well, or use treated canvas?
Thanks, Gary

By the way I have painted a couple of canoes dark blue, using Interlux Brightside and have not experiences any mold/mildew issues.

 

[Dan Lindberg]

To date, I have only used treated canvas from Rollin, I add those 1 oz mildicide packets sold in the paint dept of "home" stores to the filler when I mix it.
I don't know about mold, but insects that light on it soon die. (while the filler is drying prior to paint).

 

[Gary]

Thank you Dan, I guess I'll keep treating the canvas prior to filling. I have about enough remaining for 6 canoes of untreated canvas, next time I'll look into buying treated canvas.
Gary

 

[Rob Stevens]

Gary, et al.
I treat new canvas with zinc naphthanate before filling. The ZN dries faster than traditional filler, though I have experimented with various epoxy-based and latex fillers for faster drying/curing.
I really like how the ZN shrinks the canvas tight as a drum.

 

[Gary]

Sorry I don't mean to hijack this thread but I am interested in knowing more about Dan's filler additive? I have always treated the canvas with a product containing Zinc Naphthenate but hate the smell and drying time interruption. Plus it's getting harder to find here in Canada.

Hi Rob, yes so do I as mentioned earlier in this thread, but I was hoping for a better solution as the stuff smells horrible and I'm not sure about health risks? Plus the product I've usually purchased has dropped it's Zn content from 5% to 3%. I hope it's still as effective?
Gary

 

[1905Gerrish]

Gary, et al.
I treat new canvas with zinc naphthanate before filling. The ZN dries faster than traditional filler, though I have experimented with various epoxy-based and latex fillers for faster drying/curing.
I really like how the ZN shrinks the canvas tight as a drum.

Rob, curious which product you specifically use?

 

[Rob Stevens]

ARMORALL 3.5L Clear Zinc Wood Preservative | Home Hardware

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As mentioned above, the proportion of zinc has dropped to 2% over the past few years. Still smells awful.