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Thread: Using Ospho on Bleeding Fasteners

  1. #1
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    Default Using Ospho on Bleeding Fasteners

    Haulout this weekend, and there are some bleeding fasteners I want to take care of. Plan will be to brighten them up, hit with ospho, then cold galv zinc paint and finally epoxy with microbaloons to fill over it all.

    I've read through old threads, but still have a concern.

    Do I need to be careful not to get the ospho acid in contact with the wood? That seems difficult down in the hole. Do I need to neutralize it later? Water or baking soda or something?

    I've seen plank failure where battery acid sat on the planks, I don't want to do that at each fastener hole.

  2. #2
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    Default Re: Using Ospho on Bleeding Fasteners

    When I bought Goblin her 65+ year old iron fastenings really stained the topsides. First haul I tried attacking. Second haul I admitted failure and went to a very dark green topside paint that hid the rust bleeds.

  3. #3
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    Default Re: Using Ospho on Bleeding Fasteners

    That’s the procedure I use and haven’t seen any bad effects. If you look at the chemistry of Ospho, you will see it is not that much different than Coca Cola, just phosphoric acid. I usually dig out the plug, then take a short piece of stainless rigging and chuck it into a drill to brighten the fastener as much as possible. Then use a spray bottle of Ospho at close range in the hole. I let it dry but I’ve never worried about neutralizing it. I used to then dab CPES in and then epoxy putty the hole. I’ve quit with the CPES and now just dab the liquid epoxy in before I add the micro balloons for the filler.

  4. #4
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    Default Re: Using Ospho on Bleeding Fasteners

    Quote Originally Posted by Ian McColgin View Post
    When I bought Goblin her 65+ year old iron fastenings really stained the topsides. First haul I tried attacking. Second haul I admitted failure and went to a very dark green topside paint that hid the rust bleeds.
    i keep a spray bottle of Ospho on board and if I see an occasional bleed while at anchor, I spray it from the dinghy, wait 30 seconds or so for it to disappear (it’s like magic) then rinse off by splashing seawater on it. The Ospho doesn’t seem to affect the white hull paint, but it does stain my gray rub rail so I take care to keep it away from that.

  5. #5
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    Default Re: Using Ospho on Bleeding Fasteners

    +1 on the ospho/cold galv/epoxy filler approach. I used that on Petrel back in 2015. None of the bleeders have come back. Ospho had zero noticeable effect on the wood.

    Here's what I started with:



    After ospho and cold galv paint:





    Right after launching in November of 2015:



    How she looks now (well, last September, but it hasn't changed since then):




  6. #6
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    Default Re: Using Ospho on Bleeding Fasteners

    (Per Ian's comment about paint color - I'm sure that the dark green helps, but even a close inspection doesn't show any stains coming back on Petrel so I'm pretty convinced that the method works).

  7. #7
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    Default Re: Using Ospho on Bleeding Fasteners

    Likewise Chris. I treated most of mine over ten years ago and I haven’t seen evidence of a return in those spots, just new spots that get treated on the next haulout.

    When I did the research on the chemistry of Ospho and discovered how similar it was to Coca Cola, I had to laugh. In my youth we used to use Coke in car radiators to clean out the rust. We also would use it to clean chrome bumpers and trim.

  8. #8
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    Default Re: Using Ospho on Bleeding Fasteners

    ^^ I had heard that Coke was good for that purpose. Had no idea it was chemically similar to Ospho. Makes me think twice about drinking the stuff!

  9. #9
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    Default Re: Using Ospho on Bleeding Fasteners

    Quote Originally Posted by cstevens View Post
    ^^ I had heard that Coke was good for that purpose. Had no idea it was chemically similar to Ospho. Makes me think twice about drinking the stuff!
    The Coke or the Ospho?

  10. #10
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    Default Re: Using Ospho on Bleeding Fasteners

    I mix beer with Diet Coke sometimes - after few minutes brown flakes will form and gravitate toward bottom of the cup…...they can be mixed back in though....
    1955 Fontana 18' - 1958 Atomic 4
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  11. #11
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    Default Re: Using Ospho on Bleeding Fasteners

    Quote Originally Posted by ron ll View Post
    The Coke or the Ospho?
    Uh, well both I suppose!

    Quote Originally Posted by 2dogsnight View Post
    I mix beer with Diet Coke sometimes - after few minutes brown flakes will form and gravitate toward bottom of the cup…...they can be mixed back in though....
    To drink? Or to clean out your radiator?!

  12. #12
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    Default Re: Using Ospho on Bleeding Fasteners


    I have found Ospho to be GOOD for the wood. It eliminates the black rust damage.
    Changes iron oxide into iron phosphate.
    Gets the black out of fir, oak, cedar.
    Try spraying it on purpleheart!
    Give it time for the chemical reaction to finish before applying epoxy.
    I prefer to give it lots of time over washing it out with water, the white residue is supposed to be actually good for the primer.
    It's not the same as battery acid.

  13. #13
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    Default Re: Using Ospho on Bleeding Fasteners

    Looks like those vice grips could use a little Ospho (or Coke).

  14. #14
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    Default Re: Using Ospho on Bleeding Fasteners

    Using Ospho will treat only the area you have access to. If water gets around the epoxy and micro balloons, it hits the untreated part of the bolt, then rust follows the path back out to the surface.

    I suggest modifying to a process I had very good luck with thousands of Steel/Iron nail heads. Get to surface of bolt/nail and bust the rust off via your favorite choice (modified screw driver). This process also crumbles away most of the surrounding wood with the destroyed cell structures (delignified). I picked out all the spongey stuff around the head, then soaked the whole area with penetrating epoxy. This created a barrier between what would eventually become surface and nail head and surrounding shank as far as epoxy would soak in. I did not use OSPHO, but simply backfilled with Micro Balloons and Epoxy.

    With ordinary Alkyd enamel over primer, I had NO bleeders for several years, and then only about a dozen fast forwarding ten years.

    AFTER 9 years

    Last edited by BrianM; 06-06-2018 at 03:10 PM.

  15. #15
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    Default Re: Using Ospho on Bleeding Fasteners

    Good news then, I won't worry about the acid on the wood.

  16. #16
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    Default Re: Using Ospho on Bleeding Fasteners

    Quote Originally Posted by ron ll View Post
    Looks like those vice grips could use a little Ospho (or Coke).
    That's CETOL on the vice grips!

  17. #17
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    Default Re: Using Ospho on Bleeding Fasteners

    Another vote in favor of the Ospho. We did pretty much the same treatment as Chris and Ron on Duffy this year. We used one of those big giant syringes for application. After years of working with chemicals I get a pretty bad skin reaction if it gets on me, so wear gloves and long sleeves!

  18. #18
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    Default Re: Using Ospho on Bleeding Fasteners

    I sometimes use phosphoric acid products to remove rust stains from wood, but I always neutralize it after it has done its work. Though phosphoric is a relatively mild acid it can damage wood cells if left untreated after it has removed the rust. A simple treatment is to dampen the wood with a solution of water and household ammonia. i also use a hobby sandblasting pen, air powered, to remove rust from fastening heads that are not practical to remove. The sorrounding wood can be protected from erosion by masking it off with several layers of tape. Micro Mark can supply the sandblast pen.
    Jay

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