Maintenance of wood for canoeists

The reason we have to oil or paint wood, is to prevent wood from getting wet. When wood is wet, it will not only rot away in time, but it is considerably weaker too. Since wood gunwales and thwarts can be seen as the backbone of the canoe, it is important that they are rigid enough to preserve the shape of the canoe well.

Painting versus oiling

The difference between painting and oiling is that paint creates a more protecting finish on the surface of the wood. Epoxy is perhaps the most waterproof in that respect. Oiling adds some water resistance in the wood but can wear off quite easily.

Which woods to oil

The best use of oils is on so called hard woods. Hard woods like cherry, mahogany and walnut already have a high resistance to rot themselves and do not absorb high amounts of oil like soft woods can do. This high absorbency of oil makes soft woods heavy, also offsetting the advantage of using soft wood in the first place.

Which protection for what kind of canoe

For a quite rigid boat like a wood stripper canoe, the gunwales can probably best be epoxied to the hull and totally covered in epoxy and then, along with the rest of the boat, painted with a two part polyurethane varnish containing a good UV filter. Two part polyurethane varnishes are  expensive, but should be more durable than oil based varnishes when used on quite rigid wood constructions, especially when they are treated with epoxy first.

For a Wood & Canvas canoe you should use whatever is used in the first place, also depending on your own maintenance preferences, that you really will have to establish when you own such a boat! If the inwales are made from soft woods – as sometimes is the case – you should preferably use varnish.

For plastic canoes with wood gunwales oiling is probably the best, as the flexibility of these kind of boats may cause paint on gunwales to crack over time and let water in. Also for many people oiling frequently is much easier than painting regularly…
If such a canoe is stored outdoors though, the problem with wood gunwales is not so much the outside, which can be easily maintained with oil, but the part of the gunwales against the hull, where water can collect gradually and cause rot from inside out. A thorough oil treatment of the inside of new gunwales, how inconvenient that may be, is perhaps the best way to prevent that.

Which oil

The oil commonly used for wood preservation is boiled linseed oil. Boiled linseed oil will dry in a day or two but can take about 30 days to fully cure  — under good conditions. A working temperature of at least 20 degree Celsius is required to cure properly, with less than 60% air humidity and enough fresh air available, because it cures with the intake of oxygen. The intake of oxygen is the main reason that drying oils expand a bit when curing.  This is also the reason you should not leave a layer of oil on the surface, as it will only gum up when drying and prevent the curing of the oil in the wood.
Because linseed oil is a vegetable oil, it may get black mildew spots in wet conditions, especially when not fully cured. While that mildew may not be really harmful for the wood itself, it makes the coating even less waterproof and doesn’t look nice too.

Another suitable oil is tung oil, which is more waterproof and mildew resistant than linseed oil. I prefer it for furniture and the fingerboard of my guitar, but the real stuff is expensive and cures rather slow too. 

You can also use a proprietary oil like some kind of marine grade teak oil. These often are a special mix of boiled linseed oil, tung oil, resins, varnish, preservatives, solvents and whatever. They can be much easier to work with than linseed or tung oil alone, but in practice act more like paint than oil.

How to oil wood

If the wood has never been oiled before, wet sand it first to raise the grain. When dry, lightly sand the raised wood grain, clean it up and sparingly apply oil repeatedly until the wood doesn't absorb any more oil. Then use 0000 grade steel wool (or preferably bronze wool?) to clean the surface and leave it for at least two days in a as warm and dry situation as possible. Repeat this until you are satisfied (enough ;-) with the result.

Upkeep of oiled wood

When used intensive and/or stored outside, the wood trim of a canoe, especially the gunwales, should be oiled at least once a year to preserve it well. Clean well and sand roughened spots and apply oil as described above. Touch-up of worn spots can be treated with oil intermittenly when they occur. Even damaged painted wood can be treated that way as a temporary measure against rot.

Oiling a wood paddle

An oil finish is relatively soft and not really waterproof. Oiled wood will therefore absorb water in wet conditions and wear off quite easy. If you paddle a lot, you will have to frequently re-oil an oiled paddle to prevent warping or splitting of the blade. Fortunately, oiling a paddle is a lot easier than painting one.
Because the warping of one piece wood paddle blades can be a serious problem, even when oiled well, some people prefer to paint the blade and only oil the shaft and grip for a better feel.

Oiling a laminated paddle is not recommended because when wood gets wet and dry repeatedly, the lamination may fail over time.  Also soft woods in a laminated paddle can absorb quite some of oil making it heavier, which offsets the advantage of the using those relatively light weight soft woods.

Cane seat maintenance

Most cane seats are painted, and should be maintained as such. But in my experience the underside of the cane can be maintained very well with a little bit of boiled linseed or tung oil.