Alternative to the full bag of tricks

Discussion in 'Metal Boat Building' started by James Miller 401, Jun 26, 2018.

  1. James Miller 401
    Joined: Jun 2018
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    Location: France

    James Miller 401 New Member

    I live on an iron dutch barge in France in very modest circumstances after a life building wood and fiberglass boats. Iron? That's for ancient artifacts in museums, --right? My boat is close. Built in 1924, modified to a pleasure craft in 1954. I need a solution to a corrosion problem in iron. I'm 76 and disabled (no legs) so mobility is a major issue. I need to derust and treat my chain locker and some areas inside the stern that have significant corrosion scale and plates the size of a silver dollar, or 6-8cm.
    There is an anti-rust penetrant called Owatrol (used to be Penetrol, I think). I'm aware of the structural issues, but I need to get on this before I HAVE structural headaches. I can crawl into the stern and scrape, and I have a fairly powerful pressure water gun that, when set on high, descales fairly well. My thought was to chip and scrape, pressure wash and treat with a penetrant like the above. Paint after?
    Will this work- the pressure water gun?
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Do these "problems" have dire implications for the boat, and its ability to fulfil its function adequately, if untreated ? It is hard work to do properly, and knocking yourself around doing something that can be avoided, seems unwise, given your age and physical limitations. I don't have much experience with Penetrol in confined spaces, though I am impressed by its ability to put rust to sleep, it could become a very smelly space while it goes off, which could be weeks.
     
  3. James Miller 401
    Joined: Jun 2018
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    James Miller 401 New Member

    Thanks so much for the answer.
    I do need to deal with the problem before it gets out of control. I've got a wife who is 19 years younger and two kids in school, who will need a place to live for many years into a future I will not see.
    Not a sympathy ploy-just the consequences of long-made decisions.
    Is a good pressure washer useful in crude rust removal?
    --Say I used the high pressure washer and manual chipping and scraping to descale. Then, after a thorough drying, a generous coat of Owatrol anti-rust, followed by a coat of anti-rust paint
    --Red lead?
    --plain alkyd enamel anti-rust paint?
    For the experts among you, does this seem like an effective way to control rust inside the hull?
    What about the heavy, black bituminous coating used by the commercial bargemen?
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    I doubt the common garden variety of pressure cleaner would work too well at all. If you google the subject, you find that extreme pressure is required, for rust removal,especially if using water alone. Wire brushes and the like have always seemed ineffective to me, on even light rust. The most likely candidate would be one of those multi-needle gizmos that run on compressed air. Saves a lot of elbow grease, but always use eye and respiratory protection. An angle that some employ is the use of phosphoric acid rust convertors, but it is always better to get off as much rust as possible, before any treatment is applied.
     
  5. MikeJohns
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    MikeJohns Senior Member

    Best if you posted some pictures, but there's no easy shortcut. You have to remove the rust scale and it needs to be done by mechanical means.

    If you can't sand blast then as Mr E mentions, a compressor and a pneumatic needle descaler are the best choice, even a cheap air chisel works quite well. Die grinders with a carbide burr are also handy tools for cleaning out pits. A disk grinder is useful too.

    Once you've removed all the scale you can paint over a uniform oxidised rusty surface with a surface tolerant maintenance epoxy with success, but never over any scale . With any concoction regardless of manufacturers claims.
     
    Last edited: Jun 27, 2018
  6. SamSam
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    SamSam Senior Member

    Well, this thread is a little old, James probably isn't paying attention, but Penetrol to me is more like just a paint thinner. In this area on the shrimp boats and work boats for rust they use Ospho, a phosphoric acid product, thin like water, that penetrates rust and chemically turns it to... I'll just post their blurb...It's available at Home Depot and other hardware, lumberyard stores.
    Ospho http://www.ospho.com/directions.htm
    [​IMG]
    Enclosed in a boat, I'd use a respirator, safety glasses and rubber gloves and fans. Not that I always did that. You can use a brush, roller or a garden type hand pump sprayer, like the handheld bottle or the 1-2 gallon size with a spray wand.
    A scraper and wire brush works, a screwdriver or sharp pointed awl helps to dislodge flakes or heavy accumulations, you certainly don't have to get it down to bare metal, just get all the loose stuff to a reasonable degree. A pressure washer will keep the rust dust down, or even a garden hose light spray. Use a wet-dry vac to clean up everything. After the stuff drys, paint it.
     
  7. gonzo
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    gonzo Senior Member

    OSPHO is phosphoric acid. You need a positive pressure air supply in a confined area. A needle scaler is a good approach for heavy rust. Wire brush and acid is fine for surface rust or after the scale has been removed. However, if there is heavy corrosion, scraping and chipping may make holes through the plating.
     
  8. MikeJohns
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    MikeJohns Senior Member

    The coatings industry won't guarantee anything over "converted rust" being iron sulphate layers. It has to be removed by mechanical means before painting, then it's a no win situation. It seems it's best use is in steel that remains bare and unpainted. Apparently paint over iron sulpahte will always fail the adhesion tests.

    Good Needle scalers are brilliant tools Von Arx make a really good model. It's worth getting sets of different sized needles. Some folk even grind the ends to a point for the finishing passes on lighter plate.
    Then wire brush and forget rust converters just seal the surface with what's termed a surface tolerant epoxy.
     
  9. Lepke
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    Lepke Junior Member

    I use a product Archoil5100. It is water based and dissolves rust/corrosion down to clean metal. Finished metal looks a little like it was sand blasted. It's a concentrate that dilutes with water 16:1. In thick rust, I saturate cotton calking and fix it in place. On light rust it can be brushed on. Available at archoil.com, maybe ebay or Amazon.
    When I first started using this product I experimented with pliers, found in a salt water bilge. Pliers were frozen and had about 1-2mm of rust. Soaked overnight, the pliers were free and rust free. Except for looseness and pitting, the pliers were usable.
     

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  10. MikeJohns
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    MikeJohns Senior Member

    That’s what’s called a Chelating Agent. They are used in large quantities by several industries, Electroplaters especially have tons of it . It's quite cheap if you buy it by the drum.
    It's used a lot in ship maintenance for cleaning up the internals of steel piping and boilers.

    But they are best used with full immersion or a spray system. They are quite slow acting and you have to dispose of around 25 parts of fluid to 1 of oxide removed by weight. A continual spray system works well.

    Considered impractical for commercial use for cleaning the hulls of steel craft, but it could be used with your suggested poultice method, especially for someone with the time to re-wet the poultice regularly for a month to dissolve the deeper scale. Might be worth a try.
     
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