Pot Metal Repair

LanceB
LanceB Senior Contributor
in HUDSON
I'm looking at doing some pot metal repair for some trim pieces.  Have any of you used Super Alloy 1 from Muggy Weld?




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  • 35 Terraplane
    35 Terraplane Senior Contributor
    I'd be wearing a high quality welding respirator when using it.  Says it contains cadmium which is very toxic.
  • Jon B
    Jon B Administrator
    edited April 2020
    Not sure about "Super Alloy", but years ago I tried a welding rod called "AlumiWeld" and was quite impressed.  https://openforum.hetclub.org/discussion/346535/AlumiWeld  It's apparently an aluminum solder and I tried it out, soldering a short section of aluminum angle to a longer section of aluminum.  (You only need a propane torch.)  I then hit it hard with a hammer and all I managed to do was to bend one leg of the short welded piece.

    Then, just for grins and giggles, I took an old, pitted pot metal hood ornament and tried to fill some of the holes using the AlumiWeld and the propane torch.  I think it would have worked if I could have controlled the heat better, because the AlumiWeld's melting point is just below that of the pot metal.  So the ornament melted about the same time the AlumiWeld did.  Part of the problem was the concentrated heat of the torch.  Hard to control. 

    I think if I had had a high-temperature oven and could have put the ornament in it, and gradually raised the temperature of the entire ornament to just the right level, I could have dabbed the welding rod into each of the pits and, in this way, filled all the holes.  But that was 40+ years ago, and I got distracted, and lost interest.
  • ESSX28-1
    ESSX28-1 Senior Contributor
    Anyone know why pot metal (muckmetal) pits?

  • Geoff
    Geoff Senior Contributor
    Basically, it is oxidisation of the zinc.   As steel rusts when exposed to oxygen, zinc also "white rusts".   Pot metal is an alloy of lead and zinc.
  • Geoff
    Geoff Senior Contributor
    And of course pot metal doesn't exactly pit, it gets pimples!
  • 40indianssgmailcom
    40indianssgmailcom Senior Contributor
    The trick with pot metal is to strip the part to bare metal,  drill the pits to remove the cancer,copper plate it, then silver solder the pits.  After all this file and sand the surface to replicate the original part, copper plate again, polish to remove any minor blemishes, then nickel plate, and if you want chrome put it in the chrome tank.  Nickel is the warm silver color while chrome is clear and tends to make the nickel have a blue cast and colder look.  Ask me how I know, I worked with the chrome shop to do the grunt work while they did the polishing and plating.  I saved a lot of money but what was my time worth?  I also learned a new skill
  • Geoff
    Geoff Senior Contributor
    Good luck trying to silver solder old die-cast!   It will burst open well before the melting temp of silver solder.  
  • 40indianssgmailcom
    40indianssgmailcom Senior Contributor
    I will have another look at my solder but I am almost certain it was silver solder but it may have been a percentage of silver and lead.  Any chrome plating shop can tell you what they use and that is what I did.  My parts turned out well and I worked with Art Brass Plating in Seattle.  I also had them doe the nickel plating for my 1940 Indian Sport Scout
  • Geoff
    Geoff Senior Contributor
    Normal silver solder( Eaziflo)  requires a cherry-red heat to melt, which would destroy old diecast.   There are several alloy solders which work with aluminium and zinc, but you have to be  very careful with anything with zinc in  it.   Will be interested to know the exact composition of the solder you used, and method of application. 
  • lostmind
    lostmind Expert Adviser
    edited April 2020
    Type your commhttps://www.google.com/search?source=hp&ei=WcalXvGsGr6qytMPm92pwAs&q=how+to+solder+pits+in+pot+metal&oq=how+to+solder+pits+in+pot&gs_lcp=CgZwc3ktYWIQARgBMggIIRAWEB0QHjIICCEQFhAdEB4yCAghEBYQHRAeMggIIRAWEB0QHjIICCEQFhAdEB4yCAghEBYQHRAeOgUIABCDAToCCAA6BAgAEA06BggAEBYQHjoICAAQCBANEB46BggAEA0QHjoFCCEQqwJQZVjXVGDzc2gAcAB4AIAB1geIAfQZkgEIMTUuOS42LTGYAQCgAQGqAQdnd3Mtd2l6&sclient=psy-ab#kpvalbx=_a8alXq-XI8qyytMP7LKc0Ak39ent



    You tube video, might need to open new window
  • lostmind
    lostmind Expert Adviser
    edited April 2020
    That google search is a youtube video, you might have to open in new window/


    Here's a chrome shop that uses silver solder
    https://www.paulschrome.com/index.php/restoration-a-repair

  • 40indianssgmailcom
    40indianssgmailcom Senior Contributor
    I used an alloy  that was recommended by the plating shop so here is a photo or two of the packaging and contents.  If I remember correctly it was about $10.  I don't know the melting temp of pot metal but this melts at 450* F as stated on the package.  I did not suffer any pot metal blowouts due to temp.
  • Geoff
    Geoff Senior Contributor
    Did you use a torch, or a soldering iron?

  • 40indianssgmailcom
    40indianssgmailcom Senior Contributor
    I used the small butane torch sold at harbor freight for about $14.  It has a soft flame with enough heat to do the soldering.  It is refillable, about six inches tall and 1-1/4" diameter
  • Browniepetersen
    Browniepetersen Senior Contributor

    I use the same method that 40indianssgmailcom talks about.  Have done quite a bit of it over the past 30 years and the young men that do it today at the shop where I worked still do it that way.  It is labor intensive and ergo the cost,  But, that is the only method that I have seen that really works.  There are a few parts that I see that were done in the 70's and they still look great.


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