Laminating over rust...

Discussion in 'Materials' started by Lew Morris, Dec 28, 2006.

  1. Lew Morris
    Joined: Jun 2001
    Posts: 124
    Likes: 4, Points: 18, Legacy Rep: 92
    Location: Pismo Beach, Ca

    Lew Morris Industrial Designer

    Yeah, I know... don't.

    I did a search before posting this but the subject is too complex for the search engine.

    I'm rebuilding the swing keel on my old McGregor. It is, or I should say was, basically a fiberglass fiberglass fairing fitted around a 4" x 5/8" steel bar with a lead bulb bolted onto the bottom. At the factory this armature was set up with the fiberglass around it and the whole thing was backfilled with an "unfilled" casting resin.

    Thirty years later water intrusion from around the pivot, and from previous owners grounding it, has caused terminal delamination of the resin from the steel armature. In additon to the exterior fairing splitting open, the steel itself had become deeply pitted, and flaked off.

    But there is substantial material left to work with.

    Here is the problem: I've ground down to bare metal but need to know if there is a chemical that should be applied PRIOR to laminating with epoxy.
     
  2. longliner45
    Joined: Dec 2005
    Posts: 1,629
    Likes: 73, Points: 0, Legacy Rep: 505
    Location: Ohio

    longliner45 Senior Member

    osfo removes rust ,,but I dont know what it will do to the surrounding fiberglass,,,,,good luck ,,longliner
     
  3. Lew Morris
    Joined: Jun 2001
    Posts: 124
    Likes: 4, Points: 18, Legacy Rep: 92
    Location: Pismo Beach, Ca

    Lew Morris Industrial Designer

    osfo... ??? is that a brand name, or a compound? something phosphrous maybe?

    I'm not too worried about the surrounding fiberglass, it's in the local landfill by now. Nothing left but the steel armature and the lead bulb. I'm starting from scratch with the templates I took off the old part.

    Thanks.

    Lew
     
  4. longliner45
    Joined: Dec 2005
    Posts: 1,629
    Likes: 73, Points: 0, Legacy Rep: 505
    Location: Ohio

    longliner45 Senior Member

    osfo comes in a bottel ,,we used to get it at the marina,,you pour it on and then scrub ,,and it removed rust from steel boats ,,there is also a pink jelly ,,I cant remember the name of it right now,,but it works great too,,,,,, had a brain fart ,,its called (navel jelly)
     
  5. jimslade
    Joined: Aug 2005
    Posts: 304
    Likes: 3, Points: 0, Legacy Rep: 27
    Location: north Markham

    jimslade Senior Member

    phosphoric acid. also some rust converters will work.
     
  6. Lew Morris
    Joined: Jun 2001
    Posts: 124
    Likes: 4, Points: 18, Legacy Rep: 92
    Location: Pismo Beach, Ca

    Lew Morris Industrial Designer

    Thanks for the feedback gents. If anyone is interested, I got feedback from the West Systems techies too ... it just took a week longer.

    Their recommendation was to mechanically remove as much of the iron scale, and rust, as possible. Wash the surface with alcohol, or acetone. Once dry, apply a coat of epoxy to the steel, working it into the surface with a stiff brush. When cured, roughen the surface to something like 80 grit and then laminate.

    I figured my needle gun would remove the rust and scale and provide a perfect surface for a base coat of epoxy to adhere to.

    Thanks again.

    Lew
     
  7. riggertroy
    Joined: Jul 2004
    Posts: 104
    Likes: 9, Points: 0, Legacy Rep: 85
    Location: New Zealand

    riggertroy Senior Member

    Would suggest using something after the needle gunning, say heavy duty wire brush (on an angle grinder).
    A problem I have seen with needle guns is that they drive particles of rust and dirt into the good steel, and once there are very hard to remove.

    A treatment I used on a steel deck before epoxy coating was to chip the heavy scale off, then wire brush the rest, followed by using phosphoric acid ( which was really well washed off before continuing further), wiped the surface dry, then used thinner on a rag as the final dry/wipe down, then the epoxy as soon as possible afterwards. This was not for laminating but just for coating, the coating was still in good nick the last time I saw the vessel and that was about 2years after coating it, the deck had heavy use every day, there was no lifting of the coating, bubbling underneath or other problems.
    Not sure if this will help you or not, but I do not like needle guns on a surface that needs to be clean of rust and dirt.
     
  8. Lew Morris
    Joined: Jun 2001
    Posts: 124
    Likes: 4, Points: 18, Legacy Rep: 92
    Location: Pismo Beach, Ca

    Lew Morris Industrial Designer

    All right mate ... no needle gun it is. Two years of exposure with no lifting is good enough for me. The surface is rough enough as it is already.

    Thanks for the tip!!! You've saved my ears a lot of grief!

    Lew
     
  9. Northshore
    Joined: Jan 2007
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: So california

    Northshore Junior Member

    I Know your problem very well. I have an old Venture (#40) with the same swing keel problem. It the glass has cracked in places and the inner steel rusted and expanded and then does not retract in the slot easily or drop completely. You may have carried it much further than I did by getting rid of all the glass and starting over. I have (4 times in 15 years) ground away the glass where it cracked and re-glassed. If I went as far as you did I would just toss the steel and rebuild the whole keel with cast iron and not glass at all. At least that way you can keep it painted and manage the rust.
    Dave
     
  10. Lew Morris
    Joined: Jun 2001
    Posts: 124
    Likes: 4, Points: 18, Legacy Rep: 92
    Location: Pismo Beach, Ca

    Lew Morris Industrial Designer

    northshore,

    I just reread these posts and realize I did not identify which Venture I am working on. It is a Venture 17, and to my knowledge was never built using a cast iron keel; later 21's, 22's, etc. were.

    Last summer I went through the ordeal of helping a friend drive the keel out of a Venture 22 that had been sitting on the ground (on it's keel) for five years. The steel has so swollen with rust that it would not budge. After two days spent with 1" diameter steel bars, pounding away through holes cut in the top of the centerboard casing, we got it out. The boat was a freebie that was going to be cut up and sent to the landfill.

    I did check into cast iron work. Not cheap ... a pattern to make a mold (since none exists); $2,500 ... the casting itself, about $650, and that didn't include the extra time to finish the raw casting. Getting it back from LA to San Luis Obispo; $200. I stopped there, I only paid a grand for the boat to begin with.
     

  11. Northshore
    Joined: Jan 2007
    Posts: 5
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: So california

    Northshore Junior Member

    Lew,
    Mine is a Venture 21, 68 boat #40. I'm also in LA. If you are down to just the steel and lead and plan on keeping the boat for a long time why don't you go down to Industrial Metals (Burbank) and pick out a plate of aluminum, or bronze and you will never have the rust problem again. You can drill holes in the aluminum and fill with lead to equal the weight of the steel. If you want to keep the steel and just polish all the rust away and re-glass that should work for a long time.The Navy used to prime metal with yellow zinc chromate but I'm not sure if you can buy it anymore. On the other hand, epoxy may be the best primer there is. When it comes time to get it back on you will need a jig to check the thickness. I used 2 short straight 2x2's shimmed between to the right thickness to slide over the keel. My keel is very heavy so getting it on and off and around the trailer is the worst part.
    Dave
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.