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Green brass.

Discussion in 'Cabo Yacht' started by Jrms80, Dec 3, 2015.

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  1. Jrms80

    Jrms80 Member

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    My head is spinning...I think I need another scotch.
  2. captholli

    captholli Senior Member

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    I'll join u!!
    It's not important enough to keep beating this horse so I'll move on to another thread. If fact and science isn't enough to move someone from their position than its time to mosey along little doggie.
  3. Capt Ralph

    Capt Ralph Senior Member

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    And I was trying to stay sober and get up early.
    Cheers all
  4. Marmot

    Marmot Senior Member

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    Geez, I thought the cap was saying green bronze is bad because it is caused by electrolysis or galvanic action because both are the same thing and needed special sauce to make it shiny again.
  5. Beau

    Beau Senior Member

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    In conclusion, green is not indicative of any failure.
  6. Capt J

    Capt J Senior Member

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    What would you speculate the cause would be if the bronze in that picture had a real reddish color to it?
  7. captholli

    captholli Senior Member

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    refer to post #19 . If that doesn't help you than you cant be helped. Other than that, let it go
  8. Capt J

    Capt J Senior Member

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    Galvanic corrossion is from mating two dis-similar metals together. It has nothing to do with the metal composition of Bronze, or bronze fittings attached to bronze, since it is an alloy and all metals are mixed together evenly in the composition of the alloy. Since all of the fittings in the picture are bronze, there aren't any dis-similar metals present (bronze is bronze) and in most cases and on most yachts there aren't disimilar metals in anything with sea water running through it.

    The only time I have ever seen bronze turn reddish in color, when it's in sea water or has sea water running through it, when it's not attached to any disimilar metals, it's the result of electrolysis causing wastage of the metal and pitting like in the case of propellors or rudders and bad electrolysis.
  9. captholli

    captholli Senior Member

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    You don't get it. If that fitting wasn't bonded OR had a positive potential than what would take place between the three metals present in the composition? Galvanic corrosion. I'm done with this thread and your dog with a bone mentality.
  10. Capt J

    Capt J Senior Member

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    I'm not disagreeing with you. If you had electrolysis present the copper mixed in to make bronze alloy would cause the fitting to turn reddish in color. But it's not galvanic corrosion causing it, it's electrolysis. You don't get galvanic corrosion from bronze, the metals that compromise the makeup of bronze do not cause galvanic corrosion within the alloy itself. Tie a fishing line to a bronze fitting and throw it off the dock for 6 months, pull it out and you are still going to have a green bronze fitting. You need electrolysis present that is attacking/wasting the bronze fitting in order for the metal corrosion occur and leechage of the lesser noble metals out of the alloy. Now, if you had stainless attached to bronze, submerged in saltwater, that would be a different story, that would be galvanic corrosion and you need no electrolysis present for the wastage to occur.

    For example, stainless steel bow rail doesn't generally normally turn black on it's own. BUT, as soon as you hit it with electricity (ie. weld it). It causes the one metal (forgot which one) to tarnish in the chemical makeup of the stainless steel alloy and turn the entire section black. But it needs the electricity present in order to do so.
  11. Marmot

    Marmot Senior Member

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    Oh geez ... talk about spinning heads!

    Have you ever welded stainless by any method?

    Do you really really, honestly believe the "black" color around a stainless steel weld is from electricity?

    If you really believe that then look at this video:

  12. Capt J

    Capt J Senior Member

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    When 304 or 316 satinless steel is heated to welding temperatures the Chromium combines with the Carbon leaving the steel short of Chromium and therefore unable to self repair itself. This in turn is what causes it to tarnish and turn black. It then doesn't have as good of stain resistant properties in the long run and has to be polished more often in order to stay looking yacht like.
  13. Marmot

    Marmot Senior Member

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    Capt J wrote:

    "For example, stainless steel bow rail doesn't generally normally turn black on it's own. BUT, as soon as you hit it with electricity (ie. weld it). It causes the one metal (forgot which one) to tarnish in the chemical makeup of the stainless steel alloy and turn the entire section black. But it needs the electricity present in order to do so."
  14. Capt J

    Capt J Senior Member

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    Well, the heat from the electricity of welding it. You get the heat from the amount of electricity you're using to weld, either with 308L or 316L.
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