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Hey all,
I came into a supply of pure antimony and decided to alloy it with some pure lead. I wanted to cast it into 50/50 ratio ingots, to later use to harden wheel weights when I want to cast up rifle bullets.
The challenge is that antimony melts at 1167 degrees, compared to pure lead's 620 melting point. But once it's alloyed with lead it will melt around 680 or so, well within the normal temp range of bullet casting furnaces.
So I fired up my casting pot and melted and fluxed (with Marvelux) 3.5 pounds of pure lead. Once melted I added 3.5 pounds of small chunks of antimony. To help it melt (since my casting pot maxes at 700 degrees) I held a MAPP gas torch on the antimony as it floated on the molten lead. As the antimony melted I stirred and fluxed the melt until the chunks were all melted.
If you are still with me ... a couple of questions. As I torched the antimony a pretty good head of white smoke was coming off the melt (I had a fan moving air across the pot and away from me). Is this normal? This smoke left a white residue on the edges of the pot. I'm wondering if this is vaporized antimony and if so I should maybe use a lower temp torch, like plain propane?
Also, the ingots are very grainy and brittle. Perhaps the ratio of antimony still too high? I can leave them as is, but if were to drop one on a concrete floor it would probably shatter. There is also quite a bit of residue left in the pot. It has a gold tinge to it and even when heated to red hot sticks to the side of the pot. It will scrape off the sides of the pot while hot. I've never had any other lead alloys stick like this ... but casting alloys are not 50% antimony.
I'm wondering if this too is normal. Tomorrow when I have more time I'm going to try and realloy the ingots with and equal amount of lead, bringing the antimony content to 25%. I'm hoping this will clean up the pot and make the ingots act more like normal casting alloys.
Any ideas or comments about all of this? Thanks in advance.
I came into a supply of pure antimony and decided to alloy it with some pure lead. I wanted to cast it into 50/50 ratio ingots, to later use to harden wheel weights when I want to cast up rifle bullets.
The challenge is that antimony melts at 1167 degrees, compared to pure lead's 620 melting point. But once it's alloyed with lead it will melt around 680 or so, well within the normal temp range of bullet casting furnaces.
So I fired up my casting pot and melted and fluxed (with Marvelux) 3.5 pounds of pure lead. Once melted I added 3.5 pounds of small chunks of antimony. To help it melt (since my casting pot maxes at 700 degrees) I held a MAPP gas torch on the antimony as it floated on the molten lead. As the antimony melted I stirred and fluxed the melt until the chunks were all melted.
If you are still with me ... a couple of questions. As I torched the antimony a pretty good head of white smoke was coming off the melt (I had a fan moving air across the pot and away from me). Is this normal? This smoke left a white residue on the edges of the pot. I'm wondering if this is vaporized antimony and if so I should maybe use a lower temp torch, like plain propane?
Also, the ingots are very grainy and brittle. Perhaps the ratio of antimony still too high? I can leave them as is, but if were to drop one on a concrete floor it would probably shatter. There is also quite a bit of residue left in the pot. It has a gold tinge to it and even when heated to red hot sticks to the side of the pot. It will scrape off the sides of the pot while hot. I've never had any other lead alloys stick like this ... but casting alloys are not 50% antimony.
I'm wondering if this too is normal. Tomorrow when I have more time I'm going to try and realloy the ingots with and equal amount of lead, bringing the antimony content to 25%. I'm hoping this will clean up the pot and make the ingots act more like normal casting alloys.
Any ideas or comments about all of this? Thanks in advance.