New Electric Furnace

[Jammer]

I had started some Aluminum Bronze in the other electric but I ran out of copper. Need to make sure I have everything before I start. If it would melt it, it would be about 10 pounds. I'm going to do another run and see what temp I can get up to.

Richard, I sent a you PM on the other site, what's the trick to mix and pour a large batch of sand, Plaster of Paris mix? I had about 4 Gallons almost mixed and it set up in about 10 seconds.

[Rasper]

I put the water in the mixing pail, then add the plaster and let it sit for a few minutes before stirring it. Then I stir it briefly until it is mixed and then I add the sand. I use one part plaster to two parts sand. That mix seems to set up hard in about ten minutes after mixing. I have time after pouring it to mix up another batch to add to it before the first batch is set so it's all one mass.

Richard

[Jammer]

Thanks Richard, I was using 1:1 ratio and it went from too dry to too wet to a rock! I've got to get this poured today or tomorrow.

[Rasper]

You want to make the mix quite soupy—kind of like gravy.

R

[Jammer]

Just came in from pouring the investment. It seemed too wet with the POP and then I added the sand and it thickened up. I mixed it and added a little more water and it became like gravy and I poured. Started setting up by the time I had rinsed out the bucket and cleaned up a little. I used ice in the water and I think that gave me some more time. Should I have wet the sand before mixing

[Rasper]

No, just add the dry sand to the plaster mix. Sounds like you may have a successful investment.

R

[Jammer]

Just popped it out of the bucket, looks great. Good and solid. I'll take it to class tonight and hopefully we'll start burning it out and pour Brass next week. I'll have to start a new thread. Thanks a lot Richard. It will be about a 15# pour, over half is sprue and vents.

[bunyip]

Hello, Richard roughly what ratio's would you work on (water/plaster/sand)? Cheers everyone. Trev.

[Rasper]

One part plaster, two parts sand, and approx. one part water, all by volume. You have to adjust the water a bit to accommodate the different absorption rates of the dry ingredients. You want the final mix to be very soupy. For two reasons: It fills in all of the recesses, grooves, and indentations in your sculpture, and also it is not as dense after it cures, and therefore is more porous to allow for the escape of gases generated when pouring the metal.

Richard

[bunyip]

Many thanks Richard, knowing that sand varies so much in type & from different areas I had figured a bit of modification would be required to get the recipe to work correctly. Cheers Trev.