staining in ash outwale

[Lew's Canoes]

A 14 year old wood canvas canoe came into my shop for some minor work. Immediately noticed deep staining on the ash outwales - seems to be mostly in the grooves of the grain. Sanding does not get deep enough to get to it. Does not come from screws which are silicon bronze. Any thoughts on what caused this and how to remove, so we can revarnish outwales and make them look like new? See attached photo. Thanks for your help!

 

[Benson Gray]

Any thoughts on what caused this

Ash has a bad reputation for water staining. It may not sand out so replacement may be the only option. Good luck,

Benson

 

[Dave Osborn]

You might try removing the varnish and applying a teak cleaner or oxalic acid. However, stains like that usually mean the wood is compromised.
Actually it’s probably easier to mill new gunwales. Be sure to varnish the inside of the outwale and coach your customer on proper storage methods.

 

[chris pearson]

I’d strip it first. Then take oxalic acid and use a brass brush to scrub into the grain. Personally, I wouldn’t replace a gunwale just because of water stain…….keep in mind, the acid will take the color out of the wood as well so you will have to re stain it.

 

[Rob Stevens]

I have seen that "black rot" a few times, common on ash that are not stored out of the weather.
As Dave says, the wood is compromised. That mould runs deep. Consider replacing with new wood.

 

[chris pearson]

So, perhaps I’m wrong and it’s not just water stain? Interesting.

 

[Michael Grace]

Agreed that the staining is from mold, but it doesn't look like the wood (at least what's shown in the image) is compromised enough to warrant replacing the gunwales. Stripping or sanding followed by teak cleaner or oxalic acid might help. Oxalic acid is unlikely to do much since it is best as a remover of iron stains. In any case, the stain probably won't look as bad after cleaning and revarnishing, and it can be considered part of the character of the canoe. This doesn't look like a showpiece but rather a working canoe, so I'd clean it up and give it many more years - with better care if possible - before replacing gunwales.

 

[Dave Osborn]

If you want to see if the wood has weakened, take the gunwales off and flex them over the bad spot. I’ve done this to similar projects and the wood was severely weakened and broke.
Also a view of the inside of the gunwaleay show even more mold since it was likely not varnished.

 

[Dan Lindberg]

And here is why NOT to use ash on a boat/canoe.
It has great mechanical properties but is poor for rot/mold resistance.

 

[Gil Cramer]

Strip the varnish. Bleach with Chlorox overnight. The structural integrity does not appear to be compromised. Wash off the Chlorox. After it dries stain with golden oak Minwax and varnish.

 

[David Satter]

I agree with all above. But the big question is ...How much does the customer want to spend $ That usually makes the decision easier.

 

[Dave Osborn]

Hey Lew!
How are the insides of the outwales?
How far reaching is the stain?