problems casting in sand

[Niamh]

Hi everyone!
So i have figured out how to melt silver now! (Phew!) and iv tried about 10 times to cast a simple ring, but cannot get the silver to go all round the mold. Im sure im using more then enough metal, but i only manage to get half a ring and a very big spure.

I also managed to cast most of a spitfire (to go on a cufflink) but its missing a tail for the same reason. Im putting about 3-4 air holes in but noticing the smoke and heat doesn't seem to be escaping from them? could that be the cause?

[1963barnes]

Hi Niamh,
Are you using the Delph clay casting kit with the two part mold ?
If so, when you remove the model score lines out from the model and put a hole in the end of the lines ,this will allow the gasses somewhere to go ,Also melt more silver then you need so there is a weight of metal to push the silver into the mold,this silver has to be more then just molten ,use borax ,then get some residual heat into it the silver it should be swirling , move the metal around in the crucible ,make sure to heat the pour side of the crucible,if it's cold it will draw heat out of the silver as you pour, I use oxy propane and tend to reduce the oxy for 30 seconds before I pour to draw some of the oxygen out of the silver .hope this helps.
Andy



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[handmadeblanks]

Maybe your sprue is too long...or something else...Can you take a photo at each stage or perhaps take a photo when you first separate the flask after pouring?

[Niamh]

[QUOTE=1963barnes;99978]Hi Niamh,
Are you using the Delph clay casting kit with the two part mold ?
If so, when you remove the model score lines out from the model and put a hole in the end of the lines ,this will allow the gasses somewhere to go ,Also melt more silver then you need so there is a weight of metal to push the silver into the mold,this silver has to be more then just molten ,use borax ,then get some residual heat into it the silver it should be swirling , move the metal around in the crucible ,make sure to heat the pour side of the crucible,if it's cold it will draw heat out of the silver as you pour, I use oxy propane and tend to reduce the oxy for 30 seconds before I pour to draw some of the oxygen out of the silver .hope this helps.
Andy

Hi Andy, Yes im using the Delph clay method with 2 parts. Im trying to cast my ring and so i have pushed the ring half way into one side, then iv put talc on it, put the other side on and filled with sand, taken the 2 sides apart, made 6 air holes and lines going from the imprint to the holes to make channels for the heat to escape, then i have made a funnel for the molten silver to pour down, im thinking like HANDMADEBLANKS said and maybe my spure is too long so iv made my funnel deeper and plan on trying again later! thanks!