canoe wood gunwale maintenance

-- Last Updated: Jul-22-08 9:45 PM EST --

I've got a beautiful Hemlock Kestrel with wood gunwales. I try to maintain as much as paddling season allows and live in FL. Heat and humidity abound in the summer months. I keep this boat on my patio under a shade tree. I have a custom waterproof breathable cover that covers the hull while it rests on carpeted supports.

I need to do it's quarterly Watco maintenance and some sanding (nicks/gouges) but noticed mildew stains on the wood under screws that support seat/thwarts and between layers of wood. I want to get rid of these before oiling. Any recommendations on procedure to get rid of these stains?

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You could use the peroxide powder
used to pre-clean decks, but it will pull some of the pre-existing oil out of the wood. I would not use bleach.

The peroxide cleaning powder can be mixed to a milder strength than recommended on the pouch. I assume your gunwales are ash. If they are cherry, the peroxide may bleach them.

When you get the wood clean, try to get multiple oil coats into the wood, to fill the grain and not leave any spaces that hold water. Check behind the gunwales. You may be able to just loosen them to do this.

Ask the Man
Call Dave and ask him what he recommends.

On my Peregrine I’ve used teak cleaner with a stiff brush followed by lots and lots of rinsing. That wasn’t Dave’s idea but it worked fine for me. Just remember to rinse it all off.

TSP, if you can find it.
A paint store can advise as to a substitute, like deck cleaner, if you can’t. mix according to directions and scrub with a medium-soft plastic bristle brush. Rinse well, let completely dry, scuff w/ fine sandpaper, apply Watco mixed w/ a little stain, if desired. Do that once a year along with a couple of light Watco applications and your boat will actually improve in appearance.

Mildew, or fungus in general, needs food, moisture, and warmth to grow. Watco and wood are food. I’d try leaving the cover off, if your boat’s in the shade, as stagnant air can promote growth.

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Would this work? It is a peroxide product. I have used it on stained cotton canvas, but never on wood.


Anyone know of finishing oils that are
either not metabolized by mildew and mold, or are actually anti-mold?

Actually, I suspect that Watco is not an easy meal for mold and mildew.

One option might be to soak in polyurethane after thinning it with a solvent.

My uninformed opinion is that, if mildew or mold occur, they are preying on the wood itself, not the oil, and that the problem was that the oil needed to be applied repeatedly until it builds up over all the wood fibers, like a thin varnish.

I actually have some of this stuff since I am cleaning walls before painting in my apartment. Looked at directions for mildew removal and there is a mixture ratio but it says to add bleach. I don’t want to use bleach on wood so will try without this weekend and let you all know how it works out.

Danish oils…
…are natural oils, like linseed and/or tung, with metallic driers (cobalt) added. Formulas are invariably proprietary. “Boiled” linseed oil is not really boiled. It’s had driers added as well. “Raw” linseed oil will dry, but takes forever. All are softer than most varnishes and, when used as directed, form an extremely thin layer that is easy to repair, but requires constant renewal. Fungi will digest it.

Lead paint was great at resisting mildew because it’s poisonous. I think G2D is right in that the wood is what is sustaining life. Constant attention is the only way I know of to keep mold at bay, at least on less naturally durable wood, like ash.

A mild solution of household bleach…
…say, 2 parts Clorox in 10 parts water, will kill active mildew and help to remove the black/grey staining without removing color from the wood. "Wood bleach’, a two-part treatment available at some hardware stores, is much stronger and will remove some color from darker wood like walnut or mahogany. Of course, exposing bare wood to water will raise the grain, leaving a rough feel. Simply start from scratch with sandpaper and Watco. It’s quite easy, really.

Unless you can store your canoe in a controlled humidity environment (below 55% relative humidity), mildew will continue to be an annoying fact of life, I’m afraid.

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Tertiary Sodium Phospahte TSP …

– Last Updated: Jul-23-08 11:46 PM EST –

...... or commonly trisodium phosphate ,
can corrode metals .

I believe , phosphates are modified phosphoric acids . The tri means 3 hydrogen molecules have been removed , I believe . Phosphate usage has been reduced in many soluble type phosphates such as "sodium" , because in many cases , it's disposal finds it's way to our water sources , promoting an over abundance of algae growth , which feeds on the phosphates .

Most common store shelf TSP has been reduced to less than than 50% phosphate , with the other 50% or so being replaced with a carbonic acid , I believe .

If you mix the TSP you have , as per instructions w/chlorine bleach , both the phospahate and the bleach , will be very weak ppm .

Just consider any metal parts the phosphate may come into contact with . The mixed solution is mild and a good wood cleaner for mildew stains .

What about
Tung oil or a water sealer like you use on a patio deck ? I plan to get a wood gunwale boat and have thought about this and do not want to ruin my wood. ???

Are you using Watco Teak oil? Should.
Watco Teak Oil, as opposed to Watco Exterior, is a whole other beastie. Well, it’s similar but with more additives, and actually designed as a “marine applications” oil. Exterior Oil is not designed for marine environments, but generally holds up in canoes given the relatively limited exposure canoes are subject to.

Both oils have mildewcides, I find for some reason the Teak Oil works better at preventing mildew. May have more or a different mildewcide, I don’t know. I would advise you to try and clean up your existing finish as advised, and try Watco Teak. Apply it at more regular intervals to restore the anti-mildew effects, as it is probable that the mildewcide loses some effectiveness after long terms of exposure.

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Watco Exterior and Teak have mildewcides
N/M but I couldn’t fit it in the subject line. So this is the subject, that there isn’t one.

Aye though, both Watcos popular for canoe maintenance contain mildewcides. I suspect that the better penetration associated with the Teak Oil is why I see better results with it.

They used to sell glass bottles…

– Last Updated: Jul-24-08 2:07 PM EST –

...of green colored liquid 'wood preserative' at hardware stores, and they do sell mildewcide additive at paint stores. If they're oil or alcohol based, they might mix/emulsify in an oil finish. I haven't used either, though.

I'd read the warning panel carefully. My hands contact my rails more than I might initially think.

Should I remove screws
that hold up the seats so that I can work the TSP into the holes where the mildew is? i was wondering if that liquid would harm the SS screws?

depending on what grade of St.Stl. …

– Last Updated: Jul-24-08 3:39 PM EST –

...... you have as fastners , etc. (there are many) , the possibility of minor surface corrossion is there . In no way would contact with TSP hinder any structural integrety .

The content of "chromium" by percentage (low 12% / high 29%) is the main determining factor aginst resistence to corrosion (oxidation) . Also the the same applies to content % of "carbon" , less has greater resistence to corrosion (low .03% / high 3.0%) as a comparison .

In any case , practically all grades are "passive" , which basically means in your circumstance ,
< "if a minor corrosion comes to exist after contact with a corrosive substance , you should simply polish the corroded surface off with almost anything , such as st.stl. polish , mild abrasive" > .

The reason for this is the "passive" nature of st.stl. , which means the "chromium" in the alloy , will form an impermiable surface layer (invisible to the eye) upon the surface again almost immediately .
That is why when you nick , scrape or otherwise marr a st.stl. surface , the wound to the alloy does not corrode either . Basically it repairs itself corrosion wise .

if you want to get at the mildew in the holes through the wood , it seems that if you remove any bolts , srews , ferrule , etc. , you would have greater success at that .
Personally I would have to make an effort call on this one , that means if "you" want to ??
Sometimes I'm lazier than other times , lol .

same problem
I store my boats outside in S. FL, and have to remove the seats and thwarts about once a year for a thorough cleaining and resealing. Have tried both oils and varnish, and black growth (mildew?) is a problem with both.

I use soap and water with a green scrungee pad, then sand wahtever is left.

Sorry to be bearing worse news than the others.

Remove all 4 rails and all fasteners. Wipe w/ acetone, clean w/ oven cleaner, sand all surfaces. soak bleach on any remaining mold you can fine and re-sand.

Apply three coats of Armada, Cepetol or similar Epiphanes product, Get it in the bolt/screw holes. Then reassemble.

Wood is a huge issue in the humid South.

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Jeez Charlie. maybe I should have
gotten the carbon fiber gunnels. I store my boat in the garage.

We didn’t have the CobraSox rail and thwart system when you got your RapidFire. Further, a big strong guy like you doesn’t need a 25 lb tripping boat.

That said, keep up on the MinWax Spar Poly U and you’ll be fine. It’s just that when it gets started, mold requires urgent and violent action.

That reminds me about my house. It’s an issue up here in the Great North Woods too.