Last year, all my exterior brightwork was sanded, and then 3 coats of Cetol Natural were applied, followed by 2 coats of Cetol gloss. This spring, 2 more coats of gloss were put on. A few days ago, I noticed several black streaks along the port and starboard toe rails amidships, on the water side. A couple of streaks were in the "corner" where the horizontal and vertical pieces meet, but at least one was in the middle of the vertical piece. From looking through the archives, it seems as if these streaks are caused by mildew.
Judging from some previous posts, it sounds as if the mildew may be either on top of the Cetol, or in the teak itself. Before I sand off the Cetol to bleach the teak, I'd like to see if it is on top, to save a lot of work. However, someone indicated that a bleach solution can soften Cetol, and I'm wondering if applying bleach to the gloss could be a problem. If bleaching is not recommended, is there something else I can try in working on the surface of the gloss?
As far as the cleaning agent, I've seen formulas like 1 part bleach, 3 parts water, a few ounces dishwater liquid. Any other suggestions?
I'd really appreciate any advice on this!
By the way, except for this problem, I've been really pleased with using Natural + gloss, and have gotten a number of compliments on how it looks.
Cetol Problem
Moderator: Jim Walsh
mildew
Kemah,
It does sound a little strange to me that mildew would show up at this point on the wood.
I hope you get some better help then this but I would guess that if the mildew is on the top, I should be able to rub it off with a dry terry cloth rag.
If not, I'd try Lysol concentrate.
If not I'd try light sanding in that area to see if the mildew is affected.
If light sanding with say 220 doesn't remove it, I'm guessing it is on the teak, bummer!
If 220 does remove it then I would just recoat the area with clear cetol
I just had a mildew problem here at home, and finally had to remove and replace some dry wall to get rid of it!!
Good Luck with it.
Gary
It does sound a little strange to me that mildew would show up at this point on the wood.
I hope you get some better help then this but I would guess that if the mildew is on the top, I should be able to rub it off with a dry terry cloth rag.
If not, I'd try Lysol concentrate.
If not I'd try light sanding in that area to see if the mildew is affected.
If light sanding with say 220 doesn't remove it, I'm guessing it is on the teak, bummer!
If 220 does remove it then I would just recoat the area with clear cetol
I just had a mildew problem here at home, and finally had to remove and replace some dry wall to get rid of it!!
Good Luck with it.
Gary
could be it's the teak's oil
what you are seeing is most likely the teak's oil that migrates to the top surface from within and carbonize. The number one reason why any finish fails is the teak oil just below the surface. Read these guys tips on getting the oil out before applying finish and the outcome if it's not done.http://www.teakguard.com/index.html
good luck
good luck
Randy 25D Seraph #161
Black Mold
Hi All:
Dealing with the Florida state flower is a pretty big part of my boat maintenance issues and I have used Cetol exclusively on my teak for at least 8 years.
Black mold that I typically see forms round blooms on the surface of the Cetol. Despite what they say on the website Randy refereed to, I have very sucessfully used bleach and TSP to clean my teak before applying Cetol. I also use a mild solution of bleach and a sponge to remove the surface "bloom" of black mold that forms on Cetol over time. The problem is most severe in the cockpit under the bimini. Mold prefers shade it seems. For reasons that defy explanation black mold seems to form on the surface of Cetol more than on varnish or any other surface on the boat. Cetol must be a food source. I have even resorted to taking the Cetol finished teak drink holder off the boat and soaking it over night in bucket of diluted bleach solution with little ill effect on either the Cetol or the teak. That sure does remove the mold though. A similar treatment works nicely for those Nicro vents that turn black in a few months.
Diluted bleach doesn't seem to affect the Cetol but a good strong TSP solution will dull it a bit.
In my experience the black streaks under the finish are caused by a break in the Cetol finish that allows water to penetrate down to the teak and turn it dark. I dent think its really mold under the Cetol but anything is possible. The only cure is to take the Cetol off and redo that area. I get this problem any place there is a joint in the wood underneath. The movement of the joint breaks the continuity of the finish and lets water in under the finish.
I typically use a mixture of bleach and TSP to wash down the raw teak after sanding before applying the first coat of Cetol. It removes the sanding dust from the pores of the wood and I have never had either a bonding problem or mold growing under the finish.
I find that the "Teak Cleaners" are far too aggressive for my preferences.
Boyd
s/v Tern
CD 30 MkII
Fort Lauderdale, Fla.
Dealing with the Florida state flower is a pretty big part of my boat maintenance issues and I have used Cetol exclusively on my teak for at least 8 years.
Black mold that I typically see forms round blooms on the surface of the Cetol. Despite what they say on the website Randy refereed to, I have very sucessfully used bleach and TSP to clean my teak before applying Cetol. I also use a mild solution of bleach and a sponge to remove the surface "bloom" of black mold that forms on Cetol over time. The problem is most severe in the cockpit under the bimini. Mold prefers shade it seems. For reasons that defy explanation black mold seems to form on the surface of Cetol more than on varnish or any other surface on the boat. Cetol must be a food source. I have even resorted to taking the Cetol finished teak drink holder off the boat and soaking it over night in bucket of diluted bleach solution with little ill effect on either the Cetol or the teak. That sure does remove the mold though. A similar treatment works nicely for those Nicro vents that turn black in a few months.
Diluted bleach doesn't seem to affect the Cetol but a good strong TSP solution will dull it a bit.
In my experience the black streaks under the finish are caused by a break in the Cetol finish that allows water to penetrate down to the teak and turn it dark. I dent think its really mold under the Cetol but anything is possible. The only cure is to take the Cetol off and redo that area. I get this problem any place there is a joint in the wood underneath. The movement of the joint breaks the continuity of the finish and lets water in under the finish.
I typically use a mixture of bleach and TSP to wash down the raw teak after sanding before applying the first coat of Cetol. It removes the sanding dust from the pores of the wood and I have never had either a bonding problem or mold growing under the finish.
I find that the "Teak Cleaners" are far too aggressive for my preferences.
Boyd
s/v Tern
CD 30 MkII
Fort Lauderdale, Fla.