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Salve Jef,
I can see two possibilities which should get you a good result.
The first is to make "play-dough", using water, salt and flower (I think it was equal portions of salt and flour). This forms into a clay-like material, easy to hand form into conical slugs and can be baked rock hard in the kitchen oven. If you add some ocker (nice red from the craftstore), it will look a lot like the real thing. As my kids have long since left kindergarten, ask the local teacher for the recipe.
Second is a trip to the craftstore for clay, but mix this clay with coarse sand and chopped up dried grass of ricehusks or the like. This will prevent the clay from cracking when you dry and/or bake it. Clay can be fired in an open fire such as a barbecue. When working the clay, roll and pound it well to expel trapped air. This is one thing that causes breaks when firing (baking) the dried projectiles. TAKE CARE, when firing the clay in an open fire, trapped air may cause explosive cracking, showering fragments and hot coals! You could consider hopping by your local potter for tips, left over clay (his quality demands are way higher then yours, plenty clay in his tip heap at no cost) and perhaps even a firing.
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Thanks Robert, very helpful!
Jef Pinceel
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You're most welcome! Hope it helps and PLEASE keep us posted on the results (How To?)
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So I could use Plaster of Paris instead of ceramic clay for a mold? Will it withstand the heat of the melted lead?
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Salve Demetrius,
I don't suppose the question was directed at me (didn't mention Plaster of Paris) but I can confirm PoP is good for making molds to pour lead into. I used to pour my own slugs for a small "cannon" I had made in PoP molds. To be on the safe side, I would suggest nice large airholes in the castmold. Lead has a relative low melting point, so you could melt it over a cooking gas flame in a deep ladle like I did. Mind the fumes!!
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We use a two part gang mold made from oak.
Yup, oak!
Trick: line each mold half with a thin layer of clay. Why clay? To prevent the hot lead from burning away the wood. Besides, you can carve assorted words and symbols into the clay!
The clay lasts for several pours, eventualy chips out, but a new layer is easy as mud to reapply.
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Thanks, Robert,
I was asking out into the ozone, to see if anyone could confirm what I was fairly sure about...I plan to make some ceramic molds one day, but that's more difficult than plaster. Shrinkage, for one is a troublesome one for a 2 piece mold.
Will simple petroleum jelly work for a parting agent for the second half of the mold, you think?
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Back in 1994 I was excavating on Hadrian wall and obtained clay that the soldiers walked on and I used some of the clay to make a mold to put lead onto Plumbata. The rest I made sling shot. The first experiment was an air dried sling shot ,I made 2 different shapes a lozenger type and a ball type. The next set I baked in a fire.Of the 2 techniques, the fired ones were far better and would cause a lot of damage if you were hit by one. The size of them you will have to gauge by your abillity to use the sling, so make different sizes and try D
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Hi David and Tony,
Perhaps the "playdough" may work here as well. This may not have as much shrinkage as clay. A commercial filler compound saying "no shrinkage" may also solve that problem. Anyway, you can always compensate for shrikage when making the mold. I have no experience with petroleum jelly, sounds votatile when heated! :o
Perhaps good to make a wax model of the slug, use that to make the enclosing mold, saw it open into two halves when dry (diagonal cut), optionaly repair any flaking and insert some lugs to ensure a good fit when you stick it back together pre casting.
If you build up the mould using clay or filler, another way is to make one side (left or right) first, using a wooden form for the slug and pencil thick dowels for airholes, then slap the other side over it, then trimming the block to size. Put a layer of sand between the halves to prevent sticking them togeter. If you use the same clay, shrinkage should be uniform.
This could/should turn into a nice How to .. if you take pictures and record the process. :lol:
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Petroleum Jelly (Vaseline) worked perfectly with my plaster moulds.
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Thanks, guys, will be setting this up after next weekend's event. No time between now and then, though. I'll probably make a 3 or 4 slot straight line setup, with the molten lead flowing in the fat part, not the points.
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Well then, sir, wishing you lots of luck and a good pour!
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