Cleaning black off teak caprail.

I've stripped and begun refinishing the teaks in the cockpit. I'm now about to tackle the cap and handrails forward of the cockpit. There is some water damage and black (mold?) damage near the joints on some areas of the caprail and I am contemplating whether to use the 2 part acid cleaner on these, but am somewhat reluctant. My shipwright friend cautions about over zealous sanding as teak is a soft wood and too much material can be removed, so I want to proceed cautiously.

Can I just apply the cleaner to the affected sections, or will the colour be lighter I. The cleaned areas. The underlying wood is now quite bright already.

How long do I need to let this dry afterward? Product says 2 weeks which is near impossible this time of year in Vancouver.

I intend to follow up,with 2 coats Cetol Natural Teak and 6-8 coats Cetol Marine Gloss.

I wonder how deep the black can go?

The book BRIGHTWORK by Rebecca J Whitman offers just about everything that can be done re stripping old finishes. The chemical route offers results but is involved and a bit dangerous. She recommends you seal off every single way fumes can get into a boat before starting.

The five basic methods of removing finishes from wood are:
1. Heat
2. Chemical
3. Dry scraping
4. Acid bleaching
5. Sanding

I have only used 5, 1, and 3.

Thanks, but stripping the old finish off isn't the problem. There is a pattern of "black" in the grain proximate to the joint. If the pattern was more random and elsewhere, I wouldn't worry too much about it but it is more obvious as a pattern that follows where two boards join, if you get my meaning. Sorry. Don't have a photo.

You will only remove a small amount of teak sanding. To kill the mold spores and bleach the color back I use oxalic acid, which by the way is organic and in spinach, in hot water and let it dry. Then I wipe it off, wash with clean water and sand lightly when it dries. I would do the entire rail so it's even.

You can also wash the bare teak with a strong soap like dishwashing soap. It cleans the teak well. I always clean my teak just before applying the first coat with acetone so the oils in the wood are removed and the first coat of varnish can adhere better. Wear gloves and use white rags. I wipe with clean rags until the rags are not turning brown. You'll be amazed at how long the varnish holds to the teak if you clean it like this first.

I have varnish still on the rails I applied in 2000.

Capthead said:

You will only remove a small amount of teak sanding. To kill the mold spores and bleach the color back I use oxalic acid, which by the way is organic and in spinach, in hot water and let it dry. Then I wipe it off, wash with clean water and sand lightly when it dries. I would do the entire rail so it's even.

You can also wash the bare teak with a strong soap like dishwashing soap. It cleans the teak well. I always clean my teak just before applying the first coat with acetone so the oils in the wood are removed and the first coat of varnish can adhere better. Wear gloves and use white rags. I wipe with clean rags until the rags are not turning brown. You'll be amazed at how long the varnish holds to the teak if you clean it like this first.

I have varnish still on the rails I applied in 2000.

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Excellent advice.
Hollywood

So Capthead:how long would you let the wood dry after this treatment?

I also have a couple of spots on my cap rail where I had metal clips for my ladder lag-bolted down. I'm ready to refinish and will probably re-attach the same fittings. Still, I'd like to learn how to remove the black spots, even if they are out of sight. Still hesitant.

The MEK or Acetone cleaning can be varnished over as soon as you're done. Say you start at the bow and wipe to the transom, go back with a Scotchbrite to clean off any lint fuzz and you can start with a thinned first coat of varnish.

If it's a soap wash, I'd do that before the Acetone wipe and let the water dry a few hours.

Black spots can be bleached with oxalic acid. If it's difficult, wet the spot then rub the powder on the spot and brush it in lightly with a wet brush. Let it dry and wipe it off. If it isn't gone, repeat.

The 2 part cleaners are very harsh and will eat the wood, my experience anyway. I like oxalic and have had great results with it.

I scrub my teak with Cascade dishwashing detergent. Works great

Reveille said:

I scrub my teak with Cascade dishwashing detergent. Works great

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Exactly what I said earlier. Dishwashing soap works great. Oxalic acid gets the color back and even.

Capthead,
Don't mean to be disrespectful but Rebecca Whittman Who wrote a very well known and comprehensive book on finishing wood called "Brightwork .. The Art of Finishing Wood" says that the percieved need to get the oil out of teak before coating is "hogwash".

I have very successful experience w varnishing extremely oily teak too to prove she's right. BUT ... others have experienced good success but removing some or most of the oil first. So I'm led to believe that it dosn't make any difference.

However in the book she does not discuss anything but oil based finishes. So de-oiling teak may be the thing to do when contemplating polyurethane, epoxy or other non oil based finishes.

Drying of teak is usually quite quick. Teak, compared to many woods is quite resistant to water absorbtion due to the oily nature.
Any water in the joints will take longer for the water to evaporate out.
I've started varnishing within hours after a washdown. If the sun and a light breeze is out even faster.
You just have to cautious about joints or around fittings and hardware where some water can be trapped.
I also use alcohol to wipe down dew covered varnish after taking the bulk dew off with a chamois or microfibre cloth. The alcohol will pick up small quantities of moisture and take it away and then the alcohol will flash off.

I too do not worry about deoiling the wood. I do thin about 20-25% the first coat on raw wood.

manyboats said:

Capthead,
Don't mean to be disrespectful but Rebecca Whittman Who wrote a very well known and comprehensive book on finishing wood called "Brightwork .. The Art of Finishing Wood" says that the percieved need to get the oil out of teak before coating is "hogwash".

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I think it's good to remember Ms. Whittman did the vast majority of her brightwork in the PNW. So what worked there may not hold true for other climates. While I have not seen it often, I have seen varnish lift off of the wood. So a wipe down with alcohol or acetone certainly can't hurt.

I thin my first coats by 50% to get deep penetration into the wood. And brush two or three of them on one right after the other.

As to how well other finishes adhere to teak, epoxy naturally adheres perhaps the best of all. It s an adhesive after all.

As to the black stains at joints. Good advice has been given on how to get rid of them. But I have seen them go deep from time to time where you just have to learn to live with them. Or you would need to take off so much wood to remove them that you could end up with a deep low spot in the wood at the seam that would require feathering out of the wood and could still leave a dip in the rail.

Some times it's best to think of the little imperfections in the wood on an older working boat as adding character to the wood work and the varnish job.

The work continues! I have already stripped the teaks along the caprail, sides and transom in the cockpit and have 2 coats natural teak and 2 coats marine gloss (cetol). I will try and get another 6-8 coats of marine gloss on. Now stripping the caprail along the sides. I have used the 2 step teak cleaner (carefully--I didn't go nuts with it) just where the mold was evident. Evil stuff, but it seemed to work and didn't take off too much wood. It has removed much of the black. The old finish sure is thick and difficult to remove in spots. Using the heat gun and gentle putty knife action. Then I use a cabinet scrapper (card scrapper) with a burr on it to remove the stubborn stuff. This card scrapper works really well and reduces sanding significantly.

I have used the two part Semco on the black moldy stuff .It is wicked but it works. Cabinet scrapper is a good idea.It can remove material fast and give you a good finish . You will have continully refurbish the burr .

Greetings,
Regarding the Cetol Marine Gloss. I have already stripped the cap rails and applied 2 coats of Cetol regular finish. I am of two minds on whether or not to finish with several coats of Gloss. The Admiral, who is usually and will in the future be in charge of this task wants to know if maintenance of a gloss finish is more work than the regular. She is quite happy with the regular finish but I sort of like the "depth" of the gloss having already done the screen door which is a stand alone item. So, the question is to gloss or not? How does the gloss last in comparison to the regular? Help!

Someone told me gloss reflects the sun's rays and lasts longer than dull finishes that absorb the UV.

I don't have any experience with dull finishes. That is what I was told and I'm sticking with it.

RT Firefly said:

Greetings,
Regarding the Cetol Marine Gloss....So, the question is to gloss or not? How does the gloss last in comparison to the regular? Help!

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The Cetol Gloss is a harder more durable finish than the Natural or the Light which has UV protection in it. When we were in Mexico, we would only get about 9 months out of the Light which was disappointing. Later, we reapplied the Light (3 coats) and then 3 coats of the Gloss. A year later it looked good. Your mileage may differ but I think the Light or Natural, over-coated with the gloss, is the way to go.

RT: as per your question, this fellows blog is quite interesting. He finishes 10 coats of regular varnish with 2 coats of cetol high gloss because he feels it is more durable.

http://varnishteak.blogspot.ca

Jim

Greetings,
Thanks for all the input. I'm 97.612% convinced it'll be gloss. Of course I'm totally wrong if anyone (?-guess who) else gets to vote. Thanks again.

I was told the gloss high buck varnish has Tung oil and the satin has Linseed oil. I always use the gloss when I apply McCloskie's varnish. Still not very hard though.

I used System Three and got more hardness but now I'll go back to McCloskie's gloss. The System Three didn't hold up in Alaska.

That guy I mentioned in my previous post on this thread says to follow up with 2 coats of Cetol high gloss on top or your regular varnish products. He also says 12 coats...10 of varnish and 2 of Cetol.

JDCAVE said:

That guy I mentioned in my previous post on this thread says to follow up with 2 coats of Cetol high gloss on top or your regular varnish products. He also says 12 coats...10 of varnish and 2 of Cetol.

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Cetol on top of varnish!? Now there's a new one. Anybody else ever tried this?

Capt.Bill11 said:

Cetol on top of varnish!? Now there's a new one. Anybody else ever tried this?

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Never heard of that one . We are doing the Epifanes high gloss thang now. My wife is doing most of it and she likes how it goes on and that's music to my ears . We thinned first coat 50% and then 25% after that . This is all new teak . we have 4 or 5 coats ( I forget) on the doors right now . We are waiting on pollen to quit falling before varnishing the cap rails . They say the magic is in the 13th coat .I don't think we will see the magic. I just ordered some of the Epifanes brushes. I have been using some of my Dad's old brushes that he had for years. He keep them in a wooden box and they were his pride and joy.
I've used Cetol before on a sailboat and it looked pretty good but didn't last. I think I only did three coats and I'm sure I needed 3 times that much .

Yeah, I really like Epifanes. That was about all I ever used. I would go for as many coats as you can. Even if you just start putting one on every week or so. To get real longevity out of varnish you have to build up coats. That and get the grain filled and the finish as smooth as you can.

The best luck I had with Cetol jobs was by getting the wood very smooth and putting on at least 6 coats. I'd put on 3 a day, one on top of the other when I could. And then wet scuff those down with a green scuffy pad and running water the next day and add 3 more. Really held up well that way even on swim platforms. Cetol gloss came out about the time I started getting out of doing varnish jobs and running bigger boats with little or no brightwork. So I can't speak to it's longevity. Other than the best jobs I've seen with it have had 4 or more base coats and 3-4 gloss coats on top of those.

Yes, everything I've heard is 10 coats at least. Tough to do in one go in the PNW with Cetol with the "requisit" 24 hour dry time between coats. I'll shoot for 10 over the next month. May require a light sand if it sits too long between coats. I might try and get two more on in Sept.