Casting copper?

Discussion in 'General foundry chat' started by garyhlucas, Jul 23, 2020.

  1. garyhlucas

    garyhlucas Silver

    A friend would like to cast some copper. I've only done aluminum with lost foam. My furnace is rated for bronze and aluminum. Could copper be done in lost foam? I also have a collection of aluminum, steel and cast iron flasks in various sizes if sand casting makes more sense. I am waiting for a reply from him as to exactly what is he wants to cast. I believe it might be a replacement casting for a lost part.
  2. ESC

    ESC Silver Banner Member

    Gary, it might have been beginners luck, but I cast some copper EDM electrodes in Petrobond with no issues. They all had a spigot out the back that was turned to fit the electrode holder.
    It has been a while, but I think the main caution was to use a cover flux. I don't remember what I used, but I got four usable electrodes.

  3. oldironfarmer

    oldironfarmer Silver Banner Member

    I've wondered about brass and bronze in lost foam.

    I cast copper ingots to make brass or aluminum bronze from later. I just use my universal red metal flux. Without it most of the pour turns into dross so you do nee a flux.

    It's my opinion lost foam would just make a mess of porosity but I'm guessing. Really need to just try it on my next brass pour. Anybody here try lost foam brass/bronze/copper?
  4. Jason

    Jason Gold

    Not here. Bronze is too expensive for me to piss about with foam. It should work, probably better if you coat the foam in drywall mud or ceramic shell. With the shell, you can just send it through a kiln and foam be gone.
  5. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    In commercial practice, Iron is probably the most common metal cast in LF. Just like other forms of casting, there are specially formulated ferrous duty lost foam refractory coatings. They have higher refractory and permeability.

    The commercial LF coating I use is designated for all non-ferrous duty including bronzes. I've never used it with copper or copper alloys. Any melting requirements for copper and copper alloys aside, there's no reason LF can't be used just as effectively to cast copper alloys. I had an art caster contact me some time back and he routinely cast Nickle Bronze alloys in LF.

  6. Tobho Mott

    Tobho Mott Silver Banner Member

    I've done bronze lost foam a handful of times. In my experience sand float is more likely and it is less tolerant to uncoated foamies, compared with aluminum, for lost foam casting.

    Jason likes this.
  7. Jason

    Jason Gold

    YUP! You gotta coat the stuff.
  8. garyhlucas

    garyhlucas Silver

    Well, when I see what he wants to cast I will probably give it a try. I also want to cast a brass handle that I lost for my sailboat. I have some brass that I can use. So maybe I'll try that first.
  9. Jason

    Jason Gold

    Sailboat = BRONZE

    It's easy to confuse the two sometimes. Light up on it, if it tries to blow your head off, it's shitty brass.
  10. HT1

    HT1 Silver

    in the Marine enviroment , for a piece of "hardware" it is very likely to be Brass,
    and there is nothing at all wrong with a "proper" Brass in the Correct application.
    Brass is easy to work with, extremely corrosion resistant, easy to machine, and compared to Bronze... inexpensive
    but No you cannot weld Brass, so dont try... But Most Bronzes also cannot be welded .
    silicon bronze "Everdur " is not the only bronze ,
    in Marine applications you are much more likely to run into Tin Bronzes
    and Manganese Bronze , both of wich weld poorly ( which is engineer speak for just dont try)

    V/r HT1
  11. DavidF

    DavidF Administrator Staff Member Banner Member

  12. HT1

    HT1 Silver

    and Mr. tig made it extremely clear he was not welding, he said multiple times Brazing ... at 2:36 he was specific and said Helibrazing .
    the difference in welding parlance is very concise , in brazing the Base metal is not melted (Helibrazing often bridges this just a little )
    couple of things he did not metion which is important to artists, his weld(filler) will not match the color of the basemetal, and a natural patina will make the weld HIGHLY visable.
    rather then hide it. an artificial patina might be able to hide the weld, but that is basically paint

    I oxy acetylene braze brass all the time for mugs . with a proper filler choice I can make my joints almost invisable when polished (colormatch) but they will not colormatch with patina
    (weld joint gets darker) but with a proper fit that is not an issue at all

    now there is an expensive work around if you just wanna do a brass looking piece(yellow) switch over to 90/10 Copper nickel, and you can tig that up no problem, of course it will probably tripple the price of the project

    V/r HT1

    P.S. Nice Video, thanks for the addition
  13. DavidF

    DavidF Administrator Staff Member Banner Member

    I have tig welded 360 brass with 360 brass rod.
    It takes a bit of effort, but is possible.
    Using bronze rod (as above) is much easier.
  14. Jason

    Jason Gold

    That's funny. There wasnt a single piece of brass on our 36ft Cape Dory. It was all bronze and green as money. lol

    I am not a fan of "Mr tig" Watch him cook the hell out of stainless and you'll find out real quick that those who can "DO!" and those who can't "Teach!" In the Airforce we said those that can't teach, "Evaluate!"

    Remember the hell I went through on my little girl lamp? I've got 60bucks in silver and soldier sitting in the drawer and if I never touch it again it will be too soon!
    Last edited: Jul 25, 2020
  15. garyhlucas

    garyhlucas Silver

    My boat is really unusual. It is an Etap 26 and Etap was an aluminum extruder company. So most of the fittings on my boat are aluminum. However they made a mistake using stainless fasteners in aluminum and electrolysis did a job on all the lifeline parts. I made all new parts and went to aluminum bolts that are larger. My boat also has a double hull and 100% foam floatation so it is essentially unsinkable. It has no bilge and the first question most people ask is where does the bilge pump go? No Etap has ever been built with a bilge pump!

    The interior hardware is all laquered brass not bronze. Oh and the rudder shaft is a solid aluminum bar too. This boat was in the water on a mooring for 25 years and the there is no corrosion on the rudder shaft except right where it exits the hull. Turns out the yard kept painting the exposed portion with copper based bottom paint!
  16. Jason

    Jason Gold

    Ugh!! Stainless next to aluminum is big no no. Those two couldnt be further apart on the nobility scale.:(
  17. HT1

    HT1 Silver

    Bit of effort??? you sir have mastered understatement ;)

    Real world applications, I was always pulling BcupV rings in pipe fittings ,
    the only time I tried to weld brass was doing wear resistant build ups on Steel

    V/r HT1
  18. metallab

    metallab Silver

    Copper casting works fine, as long as you have a reducing environment within the furnace to keep oxidizing out. A few pieces of charcoal (or even dry wood) can help. I have made many castings of red Cu.
  19. Jason

    Jason Gold

    Richard recommended a layer of broken glass works as a cover too.
  20. metallab

    metallab Silver

    That will eat crucibles. Glass is very aggressive at such temperatures.
    Use borax, a teaspoon for 100 ml (0.8kg) of molten copper is sufficient.

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