Pam Wedd

Wood canvas canoe builder
HI folks
anyone have any success in getting rid of some of the black staining inside a canoe? I come and go with this one and usually don't do anything. this particular canoe was badly redone half a dozen years ago and the varnish blistered badly, coming up in big round patches, mostly on the planking. so of course they went grey with the rest of the wood looking quite good. They really stand out because they are so big and so round. Just wondered if there was something that would actually get rid of some of the staining and not ruin the rest of the wood in the process. i have used regular bleach 50% without a lot of success in the past.

I've got a 2 part wood bleach I've used on ash stems and keels in the past, I'm in the middle of a move but I'll try and locate it on the weekend, was a purple and white box, worked great. Sorry I cant remember the name....
I've had some success with Dekswood which is a Flood product available at Home Hardware. Scrub it in strait, let it sit, I scrub rinse with Turps.
If exposed to sunlight (find me some) it works very well. Otherwise;so-so.

I've tried many products, looked at boats treated with others, and researched the chemistry and effects of an even wider variety. By far the two best products are Te-Ka and Snappy Teak-Nu. You can search the forums, and I believe you'll find some posts that were put up after the big crash of a few years ago.

Both products are strong- far stronger than the cheaper 2-part cleaner/bleach solutions sold at home improvement stores or boating supply stores (though sometimes you can find Te-Ka or Snappy at such stores). However, while they are strong, they don't bleach in the same manner that something like sodium hypochlorite does (this is household bleach). Na hypochlorite and some other bleaches leave the wood looking unnaturally washed-out in color. Not true with Snappy and Te-Ka. When you finish treating with them, the wood is a lovely golden color but it dries to look nearly white. A light sanding and first coat of varnish and that rich, beautiful patina appears again. Very nice!


1. I believe the labels of both of these products say "not for use on mahogany", but they don't say which "mahogany", nor do they say why not to use them. However, in my experience they work fine on mahogany with no problems.

2. These are sometimes said to be "scrub-less", but scrubbing helps them work. However (there's that word again!), don't really have at it with the scrubbing. Some cuts of cedar will erode fairly easily if you scrub while wet, and old spruce can really erode. I also find that spruce tends to fuzz up quite a bit and the fuzz doesn't want to sand down. Even so, an initial sealer coat of varnish will allow you to sand spruce gunwales very smooth.

Hope this is of value. Stay warm up there!:)

thanks for the suggestions.
the only thing i found in town was the Dekswood. i do remember using some two part bleach from Goudy's in Toronto but it was so long ago that i don't remember if it worked any better than any of the over the counter bleaches. i guess i have been sniffing in too many varnish fumes to remember anything!!
will look a bit more before i resort to the Dekswood. it is sunny today..... so that is a good sign.
I agree, both brands work well, and IIRC, aren't the same or close to the same chemicals?

I've bought several batches, always mail order. Works well.

Has anyone tried Oxalic Acid? I don't have experience with it but I have a professional woodworking friend that swears by it. You can find it where people buy swimming pool supplies. Also, I did a Google search and found an Oxalic Acid Wood Bleach at "The Real Milk Paint Co." ( They have some instructions for its use there.
Oxalic acid works particularly well on iron stains. If, for example, you're working on a WWII-era canoe that had iron fastenings, oxalic acid can emove at least some of the blackish iron stains around fasteners. Rusted thwart and seat bolts, though, are tough- because the bolt goes through the entire gunwale, a large rusty bolt deposits a lot of iron in the wood. Still, oxalic acid is a big help. White oak is particularly prone to iron stains because its high tannic acid content readily reacts with any iron exposure that the wood gets.

Oxalic acid doesn't work so well, though, for some other kinds of stains; it's not very good at cleaning and brightening cedar ribs and planking that has silvered with age and exposure.

I keep oxalic acid on hand and use it frequently, but products like Snappy Teak-Nu and Te-Ka are the best for general cleaning and brightening of the whole hull.

HI Fred,

I'm not sure if I've ever applied these things to new cedar. When doing a restoration, I do all stripping, cleaning, bleaching before doing any woodwork. I could do a quick test, though, I suppose!

I only have 2 canoes under my belt, but was happy with a deck wash product I bought at Home Depot. It didn't have chlorine bleach in it and was pretty mild, but it really cleaned the wood. It was the cheapest stuff on the shelf and the guy at the store said that it wasn't the fastest working or strongest stuff they sold. It specifically said that it was good for cedar decks.

Sorry I can't recall the name. I'll look around the next time at Home Depot.

Just doing a quick google search it looks like there are a bunch of products being promoted now that ahve Oxy Clean as a base. They are mixed and have to be used with a few hours. Sounds like some research is in order
found it

turns out it was a 2 part bleach, hadnt used it since i cleaned up some ash stems and keel 20+ years ago. worked wonders. apprently the mice liked the box more than the other stuff in the boathouse...


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I can't speak to the commercial products as I've only used oxalic acid. As Michael says it works great for some types of stains. The good thing about it is that if it doesn't work, it does no harm. I've found the best way to use the stuff is to apply it in a very hot solution and give it time to work. My approach would be to try it first. If it doesn't work, then I'd try the teak products. By the way, if you need some I probably have a lifetime supply and would be glad to share.
Okay, here are some photos. Fred (why did I write "Frank"? too many chemicals?)... yes, Fred asked me how products like Snappy Teak-Nu and Te-Ka affect new cedar, so I did a test. I have some Snappy Teak-Nu on hand, and used it on some old wood and some new wood. Bottom line- it had no discernable effect on new cedar.

The first two photos below show a 1917 Old Town. The first photo shows the ribs and planking (red and white cedar, respectively) after stripping and cleaning residual sludge with a saturated solution of TSP in water- there's still a lot of blotchiness to the dry wood here. The second photo shows what the hull looked like after treating with the 2-part Snappy Teak-Nu, washing well, allowing the hull to dry, and then lightly sanding. The hull looks too bright until the first sealer coat of varnish goes on... then the patina of the wood really shows. After such treatment, the hull was very uniform in color- no blotches, stains, etc.

The third and 4th photos below show a test I did on an onld piece of planking from a 90-100-year-old Morris. This canoe was stripped, treated with TSP, and then cleaned and bleached (I think with Te-Ka... this was maybe 9 years ago). All planking was left intact, but then the wood shown here was part of a section removed for replacement. So this wood was already treated once, years ago, after which it sat getting dusty and oxidized. Yesterday, I cleaned and bleached one section with Snappy Teak-Nu, then sanded the entire board with the same grits and pressure, then varnished the lower half. Photo 3 shows a section not treated with Snappy. Photo 4 shows a section treated with Snappy. Because it had already been cleaned/bleached once before, there isn't a big change in appearance, but the newly-treated wood is brighter. Notice, though, that the ridge of paint and varnish that was under the edges of the ribs is still there in photo 3, but the Snappy took that ancient, dried crud right off the wood (photo 4). The two photos of the Morris planking (3 and 4) were made in an identical manner, so color and brightess differences are real- not an artifact of photography.

The final photo shows a piece of fresh red cedar, sanded and treated with Snappy Teak-Nu. The right side of the planking was treated (right of the red vertical line); the left side wasn't treated. I put a thinned coat of varnish on the bottom half; the top is bare. No significant change to my eyes!

Apparently Snappy, at least, doesn't affect the color/tone of new cedar. As for old wood, I wouldn't attempt to strip a canoe with one of these products, but they work extremely well for getting stains out of wood and remaining junk off the wood.



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Thank you so much for taking the time and effort to do the testing for us. If you ever get up this way, you have a friend in Pennsylvania.

Fred, aka Frank
How much of either of these products (teak-nu or te-ka) would be needed to clean the interior or a typical cedar canoe?
Sand before or after?

Just stripped the hull on a Peterbourogh Style/Peel Marine Canoe with rib and plank construction. I've ordered SnappyTeak-Nu to clean it with. Should I sand it before using the Snappy, or doesn't it matter?

IIRC, I've used maybe 1/2 gal to clean/bleach a canoe, but the way they have the pricing, you might as well buy the 2 gal kit, and plan on going more then 1 canoe. :)


I don't know if sanding helps or not, but I don't, cause I clean/bleach after TPS and the hull is usually still wet. And sanding a wet hull doesn't seem like a good idea.

And as a hindsight, being that both Snappy and Ta-KA are just chemicals, anybody know if the chemicals could be purchased "in bulk" from a chemical supplier rather then the expensive marine liveries, say in 5 gal buckets?