Home Precious Metals

Poured bars - radial flow lines

CuKevinCuKevin Posts: 1,690 ✭✭✭✭

I am curious as to why poured bars exhibit radial flow lines? I’ve not seen these bars poured firsthand, but I am assuming the mold is filled rapidly and then allowed to cool slowly. Perhaps this is not the case?

Thanks for any insight!

Choice Numismatics www.ChoiceCoin.com

CN eBay

All of my collection is in a safe deposit box!
Tagged:

Comments

  • CaptHenwayCaptHenway Posts: 31,499 ✭✭✭✭✭

    Never thought about it. Are you sure that the radial lines are not on the mold from when it was ground out?

    Numismatist. 50 year member ANA. Winner of four ANA Heath Literary Awards; three Wayte and Olga Raymond Literary Awards; Numismatist of the Year Award 2009, and Lifetime Achievement Award 2020. Winner numerous NLG Literary Awards.
  • CuKevinCuKevin Posts: 1,690 ✭✭✭✭

    @CaptHenway said:
    Never thought about it. Are you sure that the radial lines are not on the mold from when it was ground out?

    I’m not sure. I assumed the pour lines were on the top of the bar, not the section facing the mold.

    Choice Numismatics www.ChoiceCoin.com

    CN eBay

    All of my collection is in a safe deposit box!
  • The pour lines are on the top of the mold and I think they form from the silver being poured out at the right speed to cool into rings. Modern backyard pourers do it on purpose.

  • Jinx86Jinx86 Posts: 3,666 ✭✭✭✭✭

    @idratherbgardening said:
    The pour lines are on the top of the mold and I think they form from the silver being poured out at the right speed to cool into rings. Modern backyard pourers do it on purpose.

    That and it helps to tap the mould as its cooling.

  • rickoricko Posts: 98,724 ✭✭✭✭✭

    When we melted reclaimed gold into bars (a previous business that did a lot of plating) we never had those lines.... it would cool into a depression in the center, but no lines. So I have also been curious about these on bars shown here... could be movement during cooling... Cheers, RickO

  • 1630Boston1630Boston Posts: 13,772 ✭✭✭✭✭
    edited December 11, 2018 9:53AM

    @Jinx86 said:

    @idratherbgardening said:
    The pour lines are on the top of the mold and I think they form from the silver being poured out at the right speed to cool into rings. Modern backyard pourers do it on purpose.

    That and it helps to tap the mould as its cooling.

    Pour and tap at 4:30.

    https://youtu.be/eBeeqGV0Eg8

    Successful transactions with : MICHAELDIXON, Manorcourtman, Bochiman, bolivarshagnasty, AUandAG, onlyroosies, chumley, Weiss, jdimmick, BAJJERFAN, gene1978, TJM965, Smittys, GRANDAM, JTHawaii, mainejoe, softparade, derryb

    Bad transactions with : nobody to date

  • CuKevinCuKevin Posts: 1,690 ✭✭✭✭

    Thank you for posting the video.
    He does not seem to be taking special care to pour slowly and it still results in many of those radial lines.

    Choice Numismatics www.ChoiceCoin.com

    CN eBay

    All of my collection is in a safe deposit box!
  • 1630Boston1630Boston Posts: 13,772 ✭✭✭✭✭

    Could be a combination of 'tapping' the mold and heating the surface with the torch. Differential temperatures in material can do strange things :smile:
    @cukevin
    You can see that he is heating the center of the mass so that the edges cool more quickly.

    Successful transactions with : MICHAELDIXON, Manorcourtman, Bochiman, bolivarshagnasty, AUandAG, onlyroosies, chumley, Weiss, jdimmick, BAJJERFAN, gene1978, TJM965, Smittys, GRANDAM, JTHawaii, mainejoe, softparade, derryb

    Bad transactions with : nobody to date

  • MsMorrisineMsMorrisine Posts: 32,136 ✭✭✭✭✭

    Could it be from multiple pours into the mould?

    I also think it could be from uneven cooling but am unsure how it would happen.

    Current maintainer of Stone's Master List of Favorite Websites // My BST transactions
  • Jinx86Jinx86 Posts: 3,666 ✭✭✭✭✭

    To pour in graphite moulds it is important to preheat them. The graphite otherwise can be saturated with moisture from the air. That small amount of moisture can erupt when the extreme heat is introduced. Just like using a cutting torch over a cement floor. So the torch he is using is for heating the mould and to help slow the cooling of the material. The torch he is using would have no real effect on the the silver staying molten as it is far too cold of a flame for that. The torch also helps prevent the surface of the bar from caving in as it cools, giving it a much more pleasing look.

Sign In or Register to comment.