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Thread: Black Pudding / Tar Caulk

  1. #1
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    Default Black Pudding / Tar Caulk

    I am finishing a rebuild of A 21' Rock Hall semi-deadrise. She is white cypress on oak framing. I am wondering if anyone can give me info on using portland cement and roofing tar as caulk? I have heard of it referred to as black pudding - it seems to set quickly and lock into the seams - but I am wondering about long term adhesion.

  2. #2
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    Can't comment on the cement and tar mix. But I have used cement and bottom paint for problem seams on bottoms. Like 5200 on your Carharts, once it is there it is there forever!
    JG

  3. #3
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    What's wrong with FOREVER??

    If youse guys were building boatz wid STEEL... wouldn't ya WELD it?

    Which "tar" are you talking about?

    As far as I know there is the "Hot Mop" type that starts out solid and must be heated... I dont think I would use that.

    Then there is the type that is more like a thick caulk, it's used to seal around pipes and vents. That is what I would consider using in underwater seams.

    You must have talked to someone who knows about the stuff or did you create the name 'Black Pudding" why not ask them?
    Last edited by Gary E; 05-31-2006 at 12:38 PM.

  4. #4
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    I have read every post on this board of those who have used cement in the bilge to fill in low spots and avoid the little puddles. All that I have read said everytime that the wood under the cement was in excellent condition many many years later. Bill Atkin used this method in the 20's I believe and think he was one of the pioneers in this, after all back then cement was a relatively newly and available product. I have seen old houses when they use to put real wood siding on them, like 1 inch thick and have many times seen old and big knot holes patched with cement and the patches where over 50 years old and still solid and sound.. It may just be a far better deal then some kind of gook.....

  5. #5
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    Ron,
    That reminds me of a 45 or so foot long sailboat that got converted to a fishing boat. They sawed off the keel, made firewood of the mast, put in a big diesel engine, and poured what looks like a ton or two of cement or concrete in the bilge.. and 50 yrs later it's still floating.

  6. #6
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    Default Black Pudding

    The name black pudding comes from the one and only website I found with anything about tar / cement in marine use.

    http://www.tradboats.com/conseamfillers.html

    All the other black pudding hits were referring to blood sausage.

    The website says tar/portland works well, but they are referring to a specific coal tar product they are selling. I however am cheap, and I am using bitumen/tar roofing cement, and portland cement.
    The last guy to work on this boat mentioned something about the pudding mix, so I figured I would give it a try. The stuff sets quickly. Yesterday it was 90 degrees. I made up a mix of roofing tar and portland to the consistency of bread dough and shmeered it right over Bertha's newly built deadrise staves. It covered a lot of sins. It set in about 3 hours. I looks and feels like it has been on the boat for a year. This is my first rebuild of a deadrise. 8 elementary kids assist me each day. I do what I can.

  7. #7
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    They is sometimes confusion on this business of tar.
    The tar in a can you buy, like roof patch is actually asphaltum or a oil derived product.It is soft and gooey,and what I believe you want to use.
    Don't believe too many understand what coal tar actually is, it is the tar that they use for hot build up roofing, they melt it in a big gas fired boiler. But it is more like a chunk of glass, very hard and brittle and will shatter if you throw a chunk of it down on the concrete. It has to be melted to be used. This ain't what you want.....and this is literally derived from coal, not a oil product.

  8. #8
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    I'd be very curious as to how paint will cover that mixture -- what I've read on this forum leads me to expect that the 'instant' roofing tar (we called it "cold tar" in the b'iness decades ago) will bleed through most paints. Not sure how much surface sealing / paintable surface is provided by the portland cement, but, hey, whatever works!

    ;0-)
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  9. #9
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    Haven't actually calked a boat with the mixture but it was recomended for especially work type boats by a professional corker. I did mix up some using henry's roofing tar, just add the cement to get it as thick as you want. The cement alone has also been used but is generally too brittle. The tar cement mix lets the cement flex enough. I calked up a practice board that I have with several types of different goo, the cement/tar mixture has held well for about three years now and is primed and painted. While this is not below the water line on a flexing hull it is outside in the rain and snow and 40 below. It seems that this mix is more popular in the Pacific North West than anywhere else. Its cheep and I have no doubt that it will work but not totally convinced that is any better than some of the commercial products available.
    Gary.

  10. #10
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    I have a book here that gives this recipe for 'shenam':

    " Mix up tar with a sprinkling of cement, add a dash of tallow.
    Heat it up and let it cool. Once you get it right it's beautiful to use, like plasticine. It sticks to anything, even oily wood.
    Prime over the shenam before antifouling. Dont use it on seams above the waterline though, or the tar will leach through the paint."

    I dont know what sort of tar they used.
    There is nothing quite as permanent as a good temporary repair.

  11. #11
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    Quote Originally Posted by Stiletto
    Prime over the shenam before antifouling.
    Prime with what????

  12. #12
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    I use it in my boat. It stays in the seam better than brown seam compound, and it alot cheaper. On smaller seams, you may not need to use the portland cement. It's only to thicken the mixture. Since it's swallowed up in tar, it doesn't set up and get hard. The thing that I like about using it is watching the looks that you get from wooden boat nazis when they see you use it. That is priceless! Wear rubber gloves!

  13. #13
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    Where do you get this Henry's roofing tar?

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    Danny Home despot should have it , they do here anyway.

    It's comes in 3 or 4 different thickness's , the stuff called Bear $hit , blackjack , comes in tubes for caulking guns , at least in pint tubes. I'd think the thickest stuff in the tube which might be called wet and dry patch could work , how'd you'd mix the cement in I da know



    Ace also carries it here.

    BTW that tube is not Henry's brand, cleans up with paint thinner / mineral spirits , or squeeze your orange peel into your hand that works as well

    Good luck, you can do it we can help
    Last edited by Paul Girouard; 06-01-2006 at 01:27 AM.

  15. #15
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    Used to use roofing tar--the stuff in a tube--for seams below the waterline. It sets up and sticks pretty much forever. There are several drawbacks. It is messy. It also clogs any sanding equipment that hits it--a problem if you are attempting to sand bottom paint. It also has no "memory", and yields to an impact, squeezing out of the seams. It's a pretty standard, old compound. It does clean up with paint thinner, even after it hardens somewhat, and scrapes off. We quit using it about 10 years ago, mainly due to the problems in finishing off the bottom. More recently, I have been using a caulking-grade liquid neoprene, sold for same purpose as a roofing caulk. This has worked very well, is sandable, trimmable, stays flexible and sticks well. It doesn't wet-stick, however, which the tar-based stuff does.

  16. #16
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    Wet-patch and cement is at least relatively cheap. For more input from someone who recommends and uses it, go to George Buehler's web site.

    Frank

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    Default Re: Black Pudding / Tar Caulk

    Hi, I Iogged on to ask if anyone has the recipe for black pudding as it sounds like the business. So I am delighted to find this thread. Thanks. I trawled George Buehlers site and didn't find info. If anyone has more a more specific recipe/more info I'd be grateful as the ready made stuff you can buy online is a bit expensive. A.

  18. #18
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    Default Re: Black Pudding / Tar Caulk

    On old boats, with iffy bottom seams, a mixture of Portland cement and bottom paint makes a, last till hell freezes over, seam paying compound for tired old wet seams and fastening holes. However, I would not use tar based compound in its place and under no circumstances would I use tar for paying seams anywhere else on a boat unless it were for an old hooker that is not in need of a cosmeticly viable compound. Tar will ooze out on hot days and cause no end of mischief! Modern Dap, glazing coumpound mixed with a bit of litharge will make a cheap compound for use above the waterline. However unless you are seeking cheapo compound to use with cheap, old or slipshod work then, you are better off using standard oil based seam compound such as marketed by Interlux.
    Jay

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    Default Re: Black Pudding / Tar Caulk

    Quote Originally Posted by Jay Greer View Post
    On old boats, with iffy bottom seams, a mixture of Portland cement and bottom paint makes a, last till hell freezes over, seam paying compound for tired old wet seams and fastening holes. However, I would not use tar based compound in its place and under no circumstances would I use tar for paying seams anywhere else on a boat unless it were for an old hooker that is not in need of a cosmeticly viable compound. Tar will ooze out on hot days and cause no end of mischief! Modern Dap, glazing coumpound mixed with a bit of litharge will make a cheap compound for use above the waterline. However unless you are seeking cheapo compound to use with cheap, old or slipshod work then, you are better off using standard oil based seam compound such as marketed by Interlux.
    Jay
    Thank you very much for replying, Jay.

    The work on my boat is nether cheap nor slipshod but she is a rough old vessel and modern seam compounds do not seem to take well, especially as I must caulk between tides. I read about Black Pudding and was impressed and would like to try it. I have used red lead putty up till now but would prefer to use as little lead as possible as it's so noxious.

    Your formula counds interesting. By bottom paint I think you mean any of the usual anti-fouls? Do you mix it with Portland cement to a dough-like consistency? Would it dry between tides?

    Thanks again.
    A.

  20. #20
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    Default Re: Black Pudding / Tar Caulk

    Bob Hicks just republished in Messing About In Boats Albert Strange's write up of his First Cruise of the DAUNTLESS, republished from the Albert Strange Association Jib and Mizzen mag, originally published in Model Yachtsman and Canoeist, 1894. Therein Strange employed what he called "Beaumantique" to fix a leak. He describes the formula thus: "First get coal tar in sufficient Quantity, then some powdered Whiting, to which a proportion of cement has been added, and mix into a stiff black putty. (Mem: this operation makes a fearful mess of everything and everybody concerned.) Then add a little colza oil and the leak annihilator is prepared. No proportions can be given, the compounding of the ingredients in their proper ratio being really a matter of intuition or genius, depending upon the state of the weather, temperature, height ofbarometer, &c, &c. The leak having been located, it must be tenderly wiped dry, and rubbed with parafin, if treated from the inside. If attacked from the exterior, it is best to dry the wound by fire, and then the Beaumantique is laid on with a knife, pressed in tightly, and smoothed over to an artistic finish."

  21. #21
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    Default Re: Black Pudding / Tar Caulk

    The beauty of using Portland cement mixed with oil based bottom paint is that it will solidify under water. The cement powder should be mixed with the bottom paint to from a thick paste that is easily worked into the seam with a putty knife. By the way, I have worked with lead all of my life so far but have yet to test positive for it anywhere in my system other than in my backside.
    Jay

  22. #22
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    Default Re: Black Pudding / Tar Caulk

    Thank you Jay. I will try that. Re the last sentence above I won't ask.....
    A.

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