Removing red lead/Linseed oil putty caulk

Discussion in 'Wooden Boat Building and Restoration' started by Joe Conway, Nov 9, 2020.

  1. Joe Conway
    Joined: Nov 2020
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    Joe Conway New Member

    Hi,
    I am restoring a 1954 30 foot sailing yacht. It was caulked using cotton, and then red lead/Linseed oil putty. The boat has been out of the water for some time and the red lead/Linseed oil putty has gone hard and cracked in places.
    I would like to redo the hull using a modern seam compound (Interlux). So I need to remove all of the red lead/Linseed oil putty mixture first, or could I simply apply the seam compound over the red lead/Linseed oil putty?
    If the advice is to remove it - anyone got an easy way to do it!
     
  2. gonzo
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    gonzo Senior Member

  3. Joe Conway
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    Joe Conway New Member

    I was afraid you'd say that!!
    If I remove it all am I better using a product like Interlux seam sealant instead of red lead/putty?
     
  4. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    I don't think you have the option of using red lead.

    Modern seaming compound is far superior any way.
     
  5. gonzo
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    gonzo Senior Member

    Modern products are much superior to linseed based putty. However, the surfaces need to be clean and primed.
     
  6. trip the light fandango
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    trip the light fandango Senior Member

    Make sure you go with the grain, a screw driver with a right angle near the tip the thickness of the plank, a butter knife, used sometimes vertically to gain leverage for the screwdriver and if your careful a jigsaw with a plank thickness blade that has speed control. It has to remain dry , or the timber will expand making it more difficult, careful of those ribs,..!
    A quiet ,reflective yoga like time for quiet contemplation,.. ...snigger.. oops sorry.. good luck.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    Just out of curiosity, why would sound caulking need to be removed ?
     
  8. Rumars
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    Rumars Senior Member

    jehardiman likes this.
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    Certainly don't want to be removing what doesn't need to be removed, a bit like people who strip paint back to bare boards, frequently just making work for themselves.
     
  10. sdowney717
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    sdowney717 Senior Member

    When I recaulked my 37 Egg, all the old linseed putty was cracked on the sides above the waterline.
    I removed it all including the cotton strings.
    Cleaned all the edges, restore some busted edges with epoxy.
    Then used DAP Dynaflex 230 in all those seams. It defined all the planks edges, really like it.
    You fill the seam, smooth with a finger. When it dries it shrinks a little.

    For belowthe waterline, I used PL premium mixed with sawdust about 30 to 40%, used a putty knife and pressed that into cleaned out totally dry wooded planks.
    Made the b0at like one solid hull, went in dry, no swelling needed and no leaks.

    I also topped over the bare wood hull with various polyurethanes, some Sanitred Permaflex, some Black PL mixed with milled FG fibers, about 30% mixed in.

    scroll through the pics towards the end of album and you will see what I am talking about.
    https://goo.gl/photos/Y876jwe1jceTp9Zz6
     
  11. gonzo
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    gonzo Senior Member

    Caulk is a structural element on the hull. Removing the cotton and replacing it with a flexible compound is wrong. The planks will move and eventually fail at the fasteners. The main function of the caulk is to create enough friction between the planks so that they act like a panel. Many wooden hulls are ruined by removing the proper caulk by people that do not understand what it does.
     
  12. sdowney717
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    sdowney717 Senior Member

    Let's see, did this in 2005 to the underwater planks when I entirely reframed the boat and with new bronze #12 screws and had every plank off the boat
    .
    Have you EVER mixed PL Premium polyurethane with sawdust and felt the results? It is very HARD, very stiff and being a glue, the planks are locked together, they dont move much if at all, certainly not rubbing past each other.
    Did the upper hull in 2014. Have you ever felt fully dried DAP 230?
    It is a very hard rubber feel, it is not soft at all, and the the planks dont rub, they are locked in place, but they can flex. Takes 30 days for a full cure, after 7 is close.

    The only somewhat soft material is the Black PL, and I put none of that between planks as a caulk. I used it in some areas as a filler mixed with sawdust which also hardens the rubber, and as a paint like coating but it still is like a rubber meaning it stretchs and compresses a little.

    You must have no experience using these adhesives and caulks in these ways, or you would not be saying that about them.
    Your only right in that you want the planks to be tight and not move against each other as in rubbing.

    Using PL Construction adhesive and sawdust creates a wood like filler that perfectly matches the matching edges of underwater planks, and it does not fall out of seams like 3M5200 can. One way to visualize what it does is consider it like a somewhat hard gasket. It can be squeezed a little bit, it is not concrete, it's more like wood. So your creating perfect tight seamed full contact edges locked together since PL is an adhesive glue. Better than epoxy as that can crack and is like a rock and the PL-sawdust mix more like wood.

    And how many conventionally maintained wood boats are still around, very few. And part of the reason is the way they were made and the woods they were made with. They all went to the landfill and now wood boats have a poor reputation.
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    Interesting. I haven't had much to do with carvel constructed boats, but I was blissfully unaware that caulking was regarded as integral to their structural soundness, only I imagined, the aspect of watertight integrity. But obviously if adhering to the timber, is acting as a glue of sorts. Just not a glue that the structural integrity vitally depended on. Or so I, and no doubt many others, thought.
     
  14. sdowney717
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    sdowney717 Senior Member

    Traditional caulk not an adhesive, it creates a pressure on the wood plank edges as in resists their expansion as they swell up making the hull planking more unistructurally sound.
    However you can achieve that soundness, will work. What I did works extremely well and is very easy to do unlike traditional caulking of twisting and using caulking irons to slam it into seams. Traditional caulking is a learned skill, too much is bad and so is too little, and it is a lot of labor by itself. And a hull done like that can still leak as the planking edges till wear down or the gap gets too wide or the fasteners fail from exposure to sea water.

    The way I did mine, the sea water cant enter the hull.
    Some ways of doing things are best forgotten.
    Fact is most people would have sent my boat back when I bought it in 1998 to the landfill in a few years, yet here I am still able to use my boat.
     

  15. sdowney717
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    sdowney717 Senior Member

    Marine Sealant Adhesion Tests - Practical Sailor (practical-sailor.com)
    Note the PL S40 on these tests is what I used to seal the underwater hull.
    And their tests were favorable to the product.
    I also mixed PL S40 with 1/32" FG milled fibers mixed in at 30%, which I highly suggest you do as it does give it more tear resistance, toughens up the coating without sacrificing flexibility, if used for hull coating.

    If you use it to glue and fill holes, mix it with sawdust, as it lets it cure much faster! Even next day.
    And yes you can san it smooth with 40, 50, 60 grit etc.. random orbit sander.

    IT is pure common sense to know that if you mix in a FG fiber product to an adhesive glue, it is going to improve the strength and durability of the glue especially if used as a coating. You can of course also wet out fiberglass cloth with Black PL. Mixing in milled fibers is very easy to do, as is spreading the mix over a surface with a 6" plastic putty knife, and it also sticks well to itself after curing, and takes all kinds of paints.

    The only negative thing I found with paints is when using oil paints on Black PL with no fibers, the oil paint will eventually crack as oil paints shrink and get hard while your painting a surface that is rubber and not hard. The cracks is not flaking paints, it actually forms long lines just like broken glass looks.

    The solution is use Acrylic latex paints.
    I have not tried painting an above waterline Black PL mixed with 30% milled fibers and oil based paints, maybe it will crack oil based paints less.
     
    Last edited: Sep 12, 2021
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