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Old 06-21-2010, 11:17 AM   #2
Marin
Scraping Paint
 
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Join Date: Oct 2007
Posts: 13,745
Re: Linseed oil on teak

Eric---

I've used Daly's SeaFin AquaSpar (by Daly's) on teak on the inside of our GB and it's a good product. We use the satin finish but it's also available in gloss, I believe. It's a one-part, waterborne, polyurethane finish and seems quite tough. I recently used it on the minimal exterior teak on our Arima fishing boat, and so far so good, although it's only been awhile since I applied it. As to toughness, I used it on the step inside our main cabin door, so it gets trod on every time someone (or the dog) goes in and out of the boat. I did this a year ago prior to our Gulf Islands trip with guests. So far--- other than a short*white scratch courtesy of the dog--- it's held up impressively well. I believe I applied about ten coats to the step.

Daly's SeaFin Teak Oil, on the other hand, is not so great for an exterior finish. The weather will take it off pretty quick. The only use for it I've ever heard recommended by the shipwrigtt's I know who maintain the large GB charter fleet in our marina is as a temporary fix for exterior teak trim where the varnish finish has failed and been sanded down but there wasn't time to do a proper varnish repair before the boat left on its next charter. I these cases, they give the person chartering the boat a small can of teak oil and ask them to periodically apply it while they have the boat. This protects the wood from weathering so when it comes back the wood is still in good condition for a proper re-varnish job.

(This temporary repair technique will not work if you use, as we do, a finish like Bristol, because Bristol will not adhere to wood that has any sort of oil finish applied to it--- the oil must be completely removed from the wood first.)

An oil finish on exterior teak is not a Good Idea in general unless you are willing to be continually re-applying it.* A slip neighbor took all the exterior teak around the cockpit of his sailboat back to bare wood last summer and applied teak oil (I believe it was Daly's SeaFin but couldn't swear to it). If you look at his boat today, the teak has all gone back to unfinished gray. On teak decks (which I know you don't have) it can be a disaster as it traps dirt, encourages deck plank seam sealant*to loose its grip on the sides of the grooves, and ends up making (with the trapped dirt and grit) a great cutting compound that wears down the wood as you walk on it.

Teak turns black because of mold that begins to grow in the unprotected wood. Oil does a poor job of totally protecting the wood against this, which is why most shipwrights use varnish or the newer finishes like Bristol, Cetol, AquaSpar, Epifanes, etc. If the black has not become too bad, you can bleach it out of the wood with something like oxalic acid, bearing in mind that this will lighten all the teak it's applied to, not just attack the black alone. Otherwise you have no choice but to sand it out, which can end up removing a lot of wood. Best not to let it get started in the first place.

But were it our boat, I would not mess with any sort of oil on the exterior wood of a boat. To keep it looking decent, you have to keep applying it, and I mean every few weeks or so depending on what the weather is doing. If you ignore it, it will weather out and you'll end up with unprotected wood that is susceptible to crevicing and developing black mold.



-- Edited by Marin on Monday 21st of June 2010 12:22:14 PM
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