Arresting the demise of teak

[John B.]

This spring I purchased a '77 Ty. Great boat and I love to sail it more then work on it. I had an inspection before I purchased (and am very glad that I did) so I went into this knowing I have some work ahead before I get "Vahevala" into "Ship Shape and Bristol fashion". From the inspection I have three issues. 1) weeping where the keel stub mates to the ballast - this has been fixed by professionals. 2) Deck needs new paint. 3) Teak is in fair shape. Very weathered but can be restored.

I have a three year plan which follows the list above. So next year I want to paint the deck and finally get to the teak end next year as a winter project.

My question: What can I do to the teak to keep it from getting any worse. Right now it is the grey, weathered and worn look with deep grain texture. Some cracking is beginning.

Thanks in advance for any suggestions.

John B.
Ty "Vahevala"



johnb91536@aol.com

[Don Craig]

If just left alone, teak is almost indestructable. It will not rot, so there's no rush to cover it with something. Weathered gray is its natural, unfinished color. The "deep grain texture" you mention is the result of unenlightened human contact--namely, scrubbing with the grain, probably with stiff bristle brushes or scouring pads. Don't make things worse by repeating that mistake. Remarkably, it can all be brought back to show condition. I offer the same recommendation I made earlier in the week: Get a copy of Rebecca Wittman's "Brightwork: The Art of Finishing Wood" published by International Marine Publishing. May I also suggest a finish that apparently is heresy on this BB (judging from all the Cetol postings): VARNISH your teak, perhaps leaving toe rail and rub rail bare for contrast and less work. Nothing comes close to the look, protection and satisfaction of a top quality traditional varnish applied with knowledge and patience. Get Rebecca's book. And good luck on your re-do.

This spring I purchased a '77 Ty. Great boat and I love to sail it more then work on it. I had an inspection before I purchased (and am very glad that I did) so I went into this knowing I have some work ahead before I get "Vahevala" into "Ship Shape and Bristol fashion". From the inspection I have three issues. 1) weeping where the keel stub mates to the ballast - this has been fixed by professionals. 2) Deck needs new paint. 3) Teak is in fair shape. Very weathered but can be restored.

I have a three year plan which follows the list above. So next year I want to paint the deck and finally get to the teak end next year as a winter project.

My question: What can I do to the teak to keep it from getting any worse. Right now it is the grey, weathered and worn look with deep grain texture. Some cracking is beginning.

Thanks in advance for any suggestions.

John B.
Ty "Vahevala"

[Larry DeMers]

I have to disagree a little bit here. The 'natural' grey color of teak is actually teak that has lost it's oils, and has been oxidized by UV and exposure. Basicly, it is the outer layer of wood degenerating as it dries out. If allowed to continue, it will continue to loose it's oil due to oxidation, eventually cracking and warping, becoming useless. This will take some time assuredly, but make no mistake...it will happen eventually, unless the teak is sealed to prevent UV exposure.

While varnish is the traditional way to treat marine wood, especially teak, it is not the best, due to another characteristic of teak. When teak is covered with a non-porous film (varnish), internal pressure forces the teak oil towards the surface, eventually forcing the varnished surface to loosen, dry out and flake off (if not repaired in time).

The advantage of Cetol in this application is that it does form a porous surface which will allow the teaks internal pressure to escape through it's micrscopic holes.

In terms of time before refinishing, I have cetol that is three years old, and looks as good as the first year it was applied..still glossy enough to reflect your face or a boat passing by. This is my entire cockpit coaming that is like this.

I have owned wood sailboats before, and I used Captains Varnish on them..religiously. Took one down to bare wood even, and refinished to museum quality (was a C-Scow, 20 ft. Melges built racing dinghy that carries 250 sq. ft. of sail in a cat rig -could hit 15-20 kts on plane, and was a blast to sail). But that puppy was work..every year.
After 16 years, I sold her..and now regret that move.

Just a thought or two..

Larry DeMers
s/v DeLaMer
Cape Dory 30

If just left alone, teak is almost indestructable. It will not rot, so there's no rush to cover it with something. Weathered gray is its natural, unfinished color. The "deep grain texture" you mention is the result of unenlightened human contact--namely, scrubbing with the grain, probably with stiff bristle brushes or scouring pads. Don't make things worse by repeating that mistake. Remarkably, it can all be brought back to show condition. I offer the same recommendation I made earlier in the week: Get a copy of Rebecca Wittman's "Brightwork: The Art of Finishing Wood" published by International Marine Publishing. May I also suggest a finish that apparently is heresy on this BB (judging from all the Cetol postings): VARNISH your teak, perhaps leaving toe rail and rub rail bare for contrast and less work. Nothing comes close to the look, protection and satisfaction of a top quality traditional varnish applied with knowledge and patience. Get Rebecca's book. And good luck on your re-do.

This spring I purchased a '77 Ty. Great boat and I love to sail it more then work on it. I had an inspection before I purchased (and am very glad that I did) so I went into this knowing I have some work ahead before I get "Vahevala" into "Ship Shape and Bristol fashion". From the inspection I have three issues. 1) weeping where the keel stub mates to the ballast - this has been fixed by professionals. 2) Deck needs new paint. 3) Teak is in fair shape. Very weathered but can be restored.

I have a three year plan which follows the list above. So next year I want to paint the deck and finally get to the teak end next year as a winter project.

My question: What can I do to the teak to keep it from getting any worse. Right now it is the grey, weathered and worn look with deep grain texture. Some cracking is beginning.

Thanks in advance for any suggestions.

John B.
Ty "Vahevala"

demers@sgi.com

[Chris Cram]

Very interesting,
I did not realize there was an issue with pressure emanating from teak. Now I have something else to blame my varnish blemishs on. Believe me, I know that varnish can be alot of work but if built up properly and maintained with twice a year refreshing coats nothing is more beautiful. Having said that I have varnished no other surface harder to keep in good order than the toe rail and rub rail of a Cape Dory. The many surfaces and edges just ask for wear and water intrusion resulting in lifting of your beautiful varnish.

The teak on my newest Cape Dory was allowed to gray and was (I believe) not scrubed so there is very little lifting of the grain. I test cleaned a section last weekend in preparation for future varnishing---IT WAS AMAZING--after a little effort I had fresh from the manufacturer golden teak .

At this point let me make a reccomendation for varnish. We have had extremely good results when using "Epiphanes" expensive? yes! but loaded with solids and a unique color (looks almost purple in the can). applied to golden teak the finish is truly bristol.

Remember many thin coats, change tape often, lightly sand between coats after the first three. and use progressively less thinner the higher the coat. never varnish straight from the can (to avoid bubbles) slow and steady patience wins the day.

These were sometimes hard learned lesson on my 25D but they will be applied to my 30C.

Chris




"When teak is covered with a non-porous film (varnish), internal pressure forces the teak oil towards the surface, eventually forcing the varnished surface to loosen, dry out and flake off (if not repaired in time).

The advantage of Cetol in this application is that it does form a porous surface which will allow the teaks internal pressure to escape through it's micrscopic holes.

cccobx@prodigy.net

[Chris Reinke CD330]

John - I am in agreement with Larry that you should do something to prevent further problems with cracking or warping. A good coat of teak oil will help rejuvenate the wood and add back some of the missing protective elements. It will penetrate the wood and will not add to your restoration efforts next season.

RE - Cetol vs Varnish. My father and I have had this argument for the past several years. The solution was for me to apply Cetol to the toe rails, bow sprit, cockpit comings, and handrails. He then got to apply his varnish to the companionway and all cabin surfaces. The theory was that the deck mounted items which are difficult to sand (handrails) or very time consuming (toe rails) would be done in Cetol. The cabin surfaces which get minimal wear, and the companionway and hatch cover which are easy to sand with a palm sander got varnish. The difference in the appearance of the two finishes is only slightly noticeable between the companionway and the cockpit. We will most likely change one or the other so they are the same again. However, the other deck items will ALWAYS be done with Cetol.

I have to disagree a little bit here. The 'natural' grey color of teak is actually teak that has lost it's oils, and has been oxidized by UV and exposure. Basicly, it is the outer layer of wood degenerating as it dries out. If allowed to continue, it will continue to loose it's oil due to oxidation, eventually cracking and warping, becoming useless. This will take some time assuredly, but make no mistake...it will happen eventually, unless the teak is sealed to prevent UV exposure.

While varnish is the traditional way to treat marine wood, especially teak, it is not the best, due to another characteristic of teak. When teak is covered with a non-porous film (varnish), internal pressure forces the teak oil towards the surface, eventually forcing the varnished surface to loosen, dry out and flake off (if not repaired in time).

The advantage of Cetol in this application is that it does form a porous surface which will allow the teaks internal pressure to escape through it's micrscopic holes.

In terms of time before refinishing, I have cetol that is three years old, and looks as good as the first year it was applied..still glossy enough to reflect your face or a boat passing by. This is my entire cockpit coaming that is like this.

I have owned wood sailboats before, and I used Captains Varnish on them..religiously. Took one down to bare wood even, and refinished to museum quality (was a C-Scow, 20 ft. Melges built racing dinghy that carries 250 sq. ft. of sail in a cat rig -could hit 15-20 kts on plane, and was a blast to sail). But that puppy was work..every year.
After 16 years, I sold her..and now regret that move.

Just a thought or two..

Larry DeMers
s/v DeLaMer
Cape Dory 30

If just left alone, teak is almost indestructable. It will not rot, so there's no rush to cover it with something. Weathered gray is its natural, unfinished color. The "deep grain texture" you mention is the result of unenlightened human contact--namely, scrubbing with the grain, probably with stiff bristle brushes or scouring pads. Don't make things worse by repeating that mistake. Remarkably, it can all be brought back to show condition. I offer the same recommendation I made earlier in the week: Get a copy of Rebecca Wittman's "Brightwork: The Art of Finishing Wood" published by International Marine Publishing. May I also suggest a finish that apparently is heresy on this BB (judging from all the Cetol postings): VARNISH your teak, perhaps leaving toe rail and rub rail bare for contrast and less work. Nothing comes close to the look, protection and satisfaction of a top quality traditional varnish applied with knowledge and patience. Get Rebecca's book. And good luck on your re-do.

This spring I purchased a '77 Ty. Great boat and I love to sail it more then work on it. I had an inspection before I purchased (and am very glad that I did) so I went into this knowing I have some work ahead before I get "Vahevala" into "Ship Shape and Bristol fashion". From the inspection I have three issues. 1) weeping where the keel stub mates to the ballast - this has been fixed by professionals. 2) Deck needs new paint. 3) Teak is in fair shape. Very weathered but can be restored.

I have a three year plan which follows the list above. So next year I want to paint the deck and finally get to the teak end next year as a winter project.

My question: What can I do to the teak to keep it from getting any worse. Right now it is the grey, weathered and worn look with deep grain texture. Some cracking is beginning.

Thanks in advance for any suggestions.

John B.
Ty "Vahevala"

chris.reinke@transamerica.com

[Don]

Chris, By what method did you "clean" your teak, and how old (gray) is it? I'm overhauling a '77 CD28, and sanding the gray uncovers a very pale wood. It has never had anything on it.
Many thanks,
Don

Very interesting,
I did not realize there was an issue with pressure emanating from teak. Now I have something else to blame my varnish blemishs on. Believe me, I know that varnish can be alot of work but if built up properly and maintained with twice a year refreshing coats nothing is more beautiful. Having said that I have varnished no other surface harder to keep in good order than the toe rail and rub rail of a Cape Dory. The many surfaces and edges just ask for wear and water intrusion resulting in lifting of your beautiful varnish.

The teak on my newest Cape Dory was allowed to gray and was (I believe) not scrubed so there is very little lifting of the grain. I test cleaned a section last weekend in preparation for future varnishing---IT WAS AMAZING--after a little effort I had fresh from the manufacturer golden teak .

At this point let me make a reccomendation for varnish. We have had extremely good results when using "Epiphanes" expensive? yes! but loaded with solids and a unique color (looks almost purple in the can). applied to golden teak the finish is truly bristol.

Remember many thin coats, change tape often, lightly sand between coats after the first three. and use progressively less thinner the higher the coat. never varnish straight from the can (to avoid bubbles) slow and steady patience wins the day.

These were sometimes hard learned lesson on my 25D but they will be applied to my 30C.

Chris



"When teak is covered with a non-porous film (varnish), internal pressure forces the teak oil towards the surface, eventually forcing the varnished surface to loosen, dry out and flake off (if not repaired in time).

The advantage of Cetol in this application is that it does form a porous surface which will allow the teaks internal pressure to escape through it's micrscopic holes.

frazier@midcoast.com

[Chris Cram]

Don,
As to how long has my teak been bare. I don't know but quite some time. I first notice a general color change when cleaning my boat and there was a considerable change in the density of the gray color from just that experience. The wood literally brightened. the cleaner was a mild boat soap.

I had some old "Teka" cleaner about and thought I would try that. It is that cleaner which did the brightening I mentioned previously. I would, however, highly recomend using something a little less caustic initially. Don't sand too much you could end up taking off too much wood, changing the shape of some of your exterior pieces. But definately clean before you sand. You will have better results.

Chris

Chris, By what method did you "clean" your teak, and how old (gray) is it? I'm overhauling a '77 CD28, and sanding the gray uncovers a very pale wood. It has never had anything on it.
Many thanks,
Don

Very interesting,
I did not realize there was an issue with pressure emanating from teak. Now I have something else to blame my varnish blemishs on. Believe me, I know that varnish can be alot of work but if built up properly and maintained with twice a year refreshing coats nothing is more beautiful. Having said that I have varnished no other surface harder to keep in good order than the toe rail and rub rail of a Cape Dory. The many surfaces and edges just ask for wear and water intrusion resulting in lifting of your beautiful varnish.

The teak on my newest Cape Dory was allowed to gray and was (I believe) not scrubed so there is very little lifting of the grain. I test cleaned a section last weekend in preparation for future varnishing---IT WAS AMAZING--after a little effort I had fresh from the manufacturer golden teak .

At this point let me make a reccomendation for varnish. We have had extremely good results when using "Epiphanes" expensive? yes! but loaded with solids and a unique color (looks almost purple in the can). applied to golden teak the finish is truly bristol.

Remember many thin coats, change tape often, lightly sand between coats after the first three. and use progressively less thinner the higher the coat. never varnish straight from the can (to avoid bubbles) slow and steady patience wins the day.

These were sometimes hard learned lesson on my 25D but they will be applied to my 30C.

Chris



"When teak is covered with a non-porous film (varnish), internal pressure forces the teak oil towards the surface, eventually forcing the varnished surface to loosen, dry out and flake off (if not repaired in time).

The advantage of Cetol in this application is that it does form a porous surface which will allow the teaks internal pressure to escape through it's micrscopic holes.

cccobx@prodigy.net

[Larry DeMers]

What I have done on other boats that wanted a varnish finish was to clean as others have described well, then use a teak brightener,really just a bleach preparation (which is all I would use now if doing it).
This will uniformly lighten the wood, towards the light tan color usually..or slightly darker if you limit the chlorine exposure. Rince exceedingly well, using fresh water, a soft brush raked with the grain, then do it again. Allow to dry completely..overnight or longer. Then go to it with the finish of your choice.
I have to say that I have seen some of the most breathtaking varnished finishes on teak bowsprits for instance. The grain just jumps out at you and you feel like treating the piece like a coffee table or something! The boat was heading for the Caribbean, then up and around to Scotland..from Superior. The guy had 12 coats of varnish built up over the winter (he took the bow sprit off and brought the whole darn thing home!)..now that is a varnish nut!
But this is nutz from any practical standpoint you care to use. A bowsprit gets used hard, and I argue that that kind of finish belongs below decks or on protected wood, that sees light service.

Onwards!

Cheers!

Larry DeMers
s/v DeLaMer

Don,
As to how long has my teak been bare. I don't know but quite some time. I first notice a general color change when cleaning my boat and there was a considerable change in the density of the gray color from just that experience. The wood literally brightened. the cleaner was a mild boat soap.

I had some old "Teka" cleaner about and thought I would try that. It is that cleaner which did the brightening I mentioned previously. I would, however, highly recomend using something a little less caustic initially. Don't sand too much you could end up taking off too much wood, changing the shape of some of your exterior pieces. But definately clean before you sand. You will have better results.

Chris

Chris, By what method did you "clean" your teak, and how old (gray) is it? I'm overhauling a '77 CD28, and sanding the gray uncovers a very pale wood. It has never had anything on it.
Many thanks,
Don

Very interesting,
I did not realize there was an issue with pressure emanating from teak. Now I have something else to blame my varnish blemishs on. Believe me, I know that varnish can be alot of work but if built up properly and maintained with twice a year refreshing coats nothing is more beautiful. Having said that I have varnished no other surface harder to keep in good order than the toe rail and rub rail of a Cape Dory. The many surfaces and edges just ask for wear and water intrusion resulting in lifting of your beautiful varnish.

The teak on my newest Cape Dory was allowed to gray and was (I believe) not scrubed so there is very little lifting of the grain. I test cleaned a section last weekend in preparation for future varnishing---IT WAS AMAZING--after a little effort I had fresh from the manufacturer golden teak .

At this point let me make a reccomendation for varnish. We have had extremely good results when using "Epiphanes" expensive? yes! but loaded with solids and a unique color (looks almost purple in the can). applied to golden teak the finish is truly bristol.

Remember many thin coats, change tape often, lightly sand between coats after the first three. and use progressively less thinner the higher the coat. never varnish straight from the can (to avoid bubbles) slow and steady patience wins the day.

These were sometimes hard learned lesson on my 25D but they will be applied to my 30C.

Chris

"When teak is covered with a non-porous film (varnish), internal pressure forces the teak oil towards the surface, eventually forcing the varnished surface to loosen, dry out and flake off (if not repaired in time).

demers@sgi.com

[Russell]

If it isn't finished, and you don't plan on finishing it for a while, put salt water on it. Salt water preserves wood.

[sloopjohnl]

my vote is for varnish on everything inside the toerail and cetol for the toe and rub rail and taffrail.

If just left alone, teak is almost indestructable. It will not rot, so there's no rush to cover it with something. Weathered gray is its natural, unfinished color. The "deep grain texture" you mention is the result of unenlightened human contact--namely, scrubbing with the grain, probably with stiff bristle brushes or scouring pads. Don't make things worse by repeating that mistake. Remarkably, it can all be brought back to show condition. I offer the same recommendation I made earlier in the week: Get a copy of Rebecca Wittman's "Brightwork: The Art of Finishing Wood" published by International Marine Publishing. May I also suggest a finish that apparently is heresy on this BB (judging from all the Cetol postings): VARNISH your teak, perhaps leaving toe rail and rub rail bare for contrast and less work. Nothing comes close to the look, protection and satisfaction of a top quality traditional varnish applied with knowledge and patience. Get Rebecca's book. And good luck on your re-do.

This spring I purchased a '77 Ty. Great boat and I love to sail it more then work on it. I had an inspection before I purchased (and am very glad that I did) so I went into this knowing I have some work ahead before I get "Vahevala" into "Ship Shape and Bristol fashion". From the inspection I have three issues. 1) weeping where the keel stub mates to the ballast - this has been fixed by professionals. 2) Deck needs new paint. 3) Teak is in fair shape. Very weathered but can be restored.

I have a three year plan which follows the list above. So next year I want to paint the deck and finally get to the teak end next year as a winter project.

My question: What can I do to the teak to keep it from getting any worse. Right now it is the grey, weathered and worn look with deep grain texture. Some cracking is beginning.

Thanks in advance for any suggestions.

John B.
Ty "Vahevala"

[sloopjohnl]

john,
make it easy on yourself. all the teak on a ty comes off and goes back on very easily with screws, with the exception of the taffrail, toerail and rubrail. take it off this fall, take it to the workshop, sand it down to a nice smooth finish and then you have plenty of time to do the finish coating you want. i did eight coats of varnish this past winter - don't forget to thin at least the first four coats in diminishing percentages and lightly sand between coats.

This spring I purchased a '77 Ty. Great boat and I love to sail it more then work on it. I had an inspection before I purchased (and am very glad that I did) so I went into this knowing I have some work ahead before I get "Vahevala" into "Ship Shape and Bristol fashion". From the inspection I have three issues. 1) weeping where the keel stub mates to the ballast - this has been fixed by professionals. 2) Deck needs new paint. 3) Teak is in fair shape. Very weathered but can be restored.

I have a three year plan which follows the list above. So next year I want to paint the deck and finally get to the teak end next year as a winter project.

My question: What can I do to the teak to keep it from getting any worse. Right now it is the grey, weathered and worn look with deep grain texture. Some cracking is beginning.

Thanks in advance for any suggestions.

John B.
Ty "Vahevala"

[Don Craig]

"When teak is covered with a non-porous film (varnish), internal pressure forces the teak oil towards the surface, eventually forcing the varnished surface to loosen, dry out and flake off (if not repaired in time)."

Larry,

This is the first I've heard of this phenomenon. Could you direct me to a source for this information? Thanks.

If just left alone, teak is almost indestructable. It will not rot, so there's no rush to cover it with something. Weathered gray is its natural, unfinished color. The "deep grain texture" you mention is the result of unenlightened human contact--namely, scrubbing with the grain, probably with stiff bristle brushes or scouring pads. Don't make things worse by repeating that mistake. Remarkably, it can all be brought back to show condition. I offer the same recommendation I made earlier in the week: Get a copy of Rebecca Wittman's "Brightwork: The Art of Finishing Wood" published by International Marine Publishing. May I also suggest a finish that apparently is heresy on this BB (judging from all the Cetol postings): VARNISH your teak, perhaps leaving toe rail and rub rail bare for contrast and less work. Nothing comes close to the look, protection and satisfaction of a top quality traditional varnish applied with knowledge and patience. Get Rebecca's book. And good luck on your re-do.

This spring I purchased a '77 Ty. Great boat and I love to sail it more then work on it. I had an inspection before I purchased (and am very glad that I did) so I went into this knowing I have some work ahead before I get "Vahevala" into "Ship Shape and Bristol fashion". From the inspection I have three issues. 1) weeping where the keel stub mates to the ballast - this has been fixed by professionals. 2) Deck needs new paint. 3) Teak is in fair shape. Very weathered but can be restored.

I have a three year plan which follows the list above. So next year I want to paint the deck and finally get to the teak end next year as a winter project.

My question: What can I do to the teak to keep it from getting any worse. Right now it is the grey, weathered and worn look with deep grain texture. Some cracking is beginning.

Thanks in advance for any suggestions.

John B.
Ty "Vahevala"

[John R.]

What I have done on other boats that wanted a varnish finish was to clean as others have described well, then use a teak brightener,really just a bleach preparation (which is all I would use now if doing it).
This will uniformly lighten the wood, towards the light tan color usually..or slightly darker if you limit the chlorine exposure. Rince exceedingly well, using fresh water, a soft brush raked with the grain, then do it again. Allow to dry completely..overnight or longer. Then go to it with the finish of your choice.
I have to say that I have seen some of the most breathtaking varnished finishes on teak bowsprits for instance. The grain just jumps out at you and you feel like treating the piece like a coffee table or something! The boat was heading for the Caribbean, then up and around to Scotland..from Superior. The guy had 12 coats of varnish built up over the winter (he took the bow sprit off and brought the whole darn thing home!)..now that is a varnish nut!
But this is nutz from any practical standpoint you care to use. A bowsprit gets used hard, and I argue that that kind of finish belongs below decks or on protected wood, that sees light service.

Onwards!

Cheers!

Larry DeMers
s/v DeLaMer

Don,
As to how long has my teak been bare. I don't know but quite some time. I first notice a general color change when cleaning my boat and there was a considerable change in the density of the gray color from just that experience. The wood literally brightened. the cleaner was a mild boat soap.

I had some old "Teka" cleaner about and thought I would try that. It is that cleaner which did the brightening I mentioned previously. I would, however, highly recomend using something a little less caustic initially. Don't sand too much you could end up taking off too much wood, changing the shape of some of your exterior pieces. But definately clean before you sand. You will have better results.

Chris

Chris, By what method did you "clean" your teak, and how old (gray) is it? I'm overhauling a '77 CD28, and sanding the gray uncovers a very pale wood. It has never had anything on it.
Many thanks,
Don

Someone in this thread mentioned that teak does not rot and unfortunately that is not true. Under the right circumstances teak will rot just like any other wood just not as easily. It is certainly highly resistant under the right conditions but not rot proof. It can and will easily rot around seams of bungs covering screws, and at other types of seams and joints if left to weather the elements. Especially in warm damp areas such as in the south,ie: Florida.

Larry, could you please offer more details about the "pressure" in teak and how that lifts a finish? The resins in the wood certainly migrate to the surface as does moisture in any wood and that resin migration certainly compromises adhesion of a finish in time. I've simply never heard of a "pressure" per se unless you are speaking of trapped air during the application of a finish. If you can point to a source of additional information on that point I'd like to read more about it. Thanks

[Larry DeMers]

Well, I can try to explain this effect. I do not have any textual sources for you other than references to this effect in a multitude of finishing articles and books over the years.
Here is what I believe is close to what happens:

Natural teak is absolutely filled with oils, which protect the surface of the wood fiber from water intrusion, as well as insects. Allowing that surface to be exposed to UV rays, causes a drying out of that surface fiber, which then wicks the oils from underneath it towards the surface. Aiding this is an internal pressure, generated by changes in temperature.Higher temps would cause an increase in this pressure <must be a very small pressure>, which will force more oils into the depleted area, where they are oxidized by UV rays. Once UV rays have dried the teak out sufficiently, water intrusion starts to occur, which will allow the chemical changes that are a process of rotting. The wood will warp, and crack as it wants to, following the grain.

NOw during this process, the wood turns nicely grey, and makes a great non-skid surface for us to walk on. Left alone, the rotting process will allow mildew to grow with black spots spreading horizontally and vertically into the woods fiber..and we look at it and say it needs to be cleaned and 'brightened', a process that uses bleach to kill the mildew and rot. Then the wood returns to it's familiar tan coloration for a period.

Cetoling at this point will cover that surface with a porous seal. The seal is good because water never reaches the wood fiber, and the UV spectrum is prevented from reaching the wood fiber, so no oils are lost to oxidation and the wood remains stable.

That is about as good an explantion as I acan come up with this morning. I will research this a bit more and report back with what I can find out. Seems it is a continual problem with any teak on boats.

I priced out the bulkhead on my CD30..as if I was going to replace it. Guess what? You cannot. I could not find a single source of teak that would provide a piece such as we have on our boats now. You would have to settle for another species, or a laminated application over marine ply. There will come a time, perhaps we are there now even, when teak will just not be included on boats at any price within reason. It would seem that this is a valuable wood, and worth caring for properly.

Does this help?

Cheers!

Larry DeMers
s/v DeLaMer
Cape Dory 30

What I have done on other boats that wanted a varnish finish was to clean as others have described well, then use a teak brightener,really just a bleach preparation (which is all I would use now if doing it).
This will uniformly lighten the wood, towards the light tan color usually..or slightly darker if you limit the chlorine exposure. Rince exceedingly well, using fresh water, a soft brush raked with the grain, then do it again. Allow to dry completely..overnight or longer. Then go to it with the finish of your choice.
I have to say that I have seen some of the most breathtaking varnished finishes on teak bowsprits for instance. The grain just jumps out at you and you feel like treating the piece like a coffee table or something! The boat was heading for the Caribbean, then up and around to Scotland..from Superior. The guy had 12 coats of varnish built up over the winter (he took the bow sprit off and brought the whole darn thing home!)..now that is a varnish nut!
But this is nutz from any practical standpoint you care to use. A bowsprit gets used hard, and I argue that that kind of finish belongs below decks or on protected wood, that sees light service.

Onwards!

Cheers!

Larry DeMers
s/v DeLaMer

Don,
As to how long has my teak been bare. I don't know but quite some time. I first notice a general color change when cleaning my boat and there was a considerable change in the density of the gray color from just that experience. The wood literally brightened. the cleaner was a mild boat soap.

I had some old "Teka" cleaner about and thought I would try that. It is that cleaner which did the brightening I mentioned previously. I would, however, highly recomend using something a little less caustic initially. Don't sand too much you could end up taking off too much wood, changing the shape of some of your exterior pieces. But definately clean before you sand. You will have better results.

Chris

Someone in this thread mentioned that teak does not rot and unfortunately that is not true. Under the right circumstances teak will rot just like any other wood just not as easily. It is certainly highly resistant under the right conditions but not rot proof. It can and will easily rot around seams of bungs covering screws, and at other types of seams and joints if left to weather the elements. Especially in warm damp areas such as in the south,ie: Florida.

Larry, could you please offer more details about the "pressure" in teak and how that lifts a finish? The resins in the wood certainly migrate to the surface as does moisture in any wood and that resin migration certainly compromises adhesion of a finish in time. I've simply never heard of a "pressure" per se unless you are speaking of trapped air during the application of a finish. If you can point to a source of additional information on that point I'd like to read more about it. Thanks

demers@sgi.com

[Mark Yashinsky]

Instead of focusing on varnish and the ongoing maintance that it requires (film finish that sits ON the wood and does not penetrate), do a search on this board for CETOL or ARMADA or HONEY TEAK. Posts include 3-4 year testing of samples, finishing and refinishing, etc. A friend has a CD27 that I have help strip all the varnish (three years old and badly flaking) off and currently have the rub/toe rail and tiller done in Honey Teak. The tiller was done the the start of the 99 sailing season, weathered the winter out of doors (lower NY) and has been thru the 00 season w/o any maintence the entire time, AND LOOKS GREAT. The Honey Teak is a two part, penetrating polyurathene that really adheres to the wood. The boat has a bowsprit and once thisseason, slightly caught the steel piling at the end of the finger of teh slip. No damage. Everyone em/disbarking, steping on the toe rail in roughly the same spot shows no wear. Think of the ease of recoating one of these products, NO STRIPING. May not be BRISTOL PERFECT, but what do you want the boat for??? To go sailing in a nice looking boat or for her to be a "trailer queen" for a show circuit. Look into these "modern" products.