Everdur Bronze Casting

[Jammer]

Today, I fired up the furnace to melt some of the Everdur I bought from Lou. I had a little trouble getting up to heat. I changed a couple things on the burner and should have left it alone. I had some dross on top, may have been from the thread lock that was on most of the bolts.
The mold is a cast iron ship mold I bought from e-bay. I coated it with some graphite, preheated it, clamped it together and put it in some sand. Before I poured, I dropped in some copper/phos shot and it seemed to help liquefy the bronze. It poured really nice and came out better than I expected.

[dallen]

I'd say the mold could of been warmer when you poured,

looks good,

[Jammer]

I was afraid if it sticking. There detail in the mold isn't very sharp. I imagine the mold was around 500F, just a guess, I set it on top of the furnace a couple times trying not to heat it too fast. I couldn't hold on to it with my welding gloves.

[F.C.]

I agree, a little more heat to that mold and it would have given you better detail. Not bad for a first attempt. But I question whether those bolts are actually everdure bronze. Herculoy & Everdure are used primarily with casting plaques and statuary, from what I'm told. Bolts may have a foundation of the Everdure in it but it needs additives to make it hard enough to withstand torque and abrasion from tools. The dross you said was evident may have been from manganese, zinc, or magnesium. If the dross was light (small accumulation liken to a thin floating skin) could have been from simple oxidation from the bolts having sat for years in the weather.

[Rasper]

I melt a lot of Everdur and am not particularly careful about my furnace atmosphere and I get what FC described as "small accumulation liken to a thin floating skin".

Richard

[F.C.]

Best way to determine composition of the dross is to bring your melt up to a temp that causes the flux to boil around the perimeter of the melt where it meets the crucible. I always toss in a couple pieces of 1/2" copper tubing I fill with borax and pinch off the ends... like giving the melt a flux pill. Once the flux begins to boil as the crucible's content is all liquid I watch closely for a "quivering" of the melt which indicates it has reached its boiling point. At this point I shut down the furnace and skim off the surface. If there was any zinc, manganese, or magnesium in the alloy you'll see some minor flaring across the surface where the flux was skimmed. Regardless what alloy of bronze I use I never shut the furnace off till I see that "quiver" on the surface of the melt. That way I have ample time to skim and get myself ready to pull the crucible and pour and the metal temp will be at its optimum instead of being on the cool side.

[Jammer]

The slag ended up being a small, less than a golf ball, sized lump. I melted 2 kilos of bolts and ended up with this heavy lump and some glassy dross coating the inside of the crucible. I'll weigh the good metal and see just how much loss I had. I didn't use any borax or brass flux.
It may not be right to call this Everdur, it is low on Mn and Si. Just a Silicon Bronze. I didn't see any smoke or fire from Zinc and the chemistry list isn't complete so there may be some in there. I will add some more Si and Mn the next time and use some flux. The copper/phos shot sure made a difference at the end. I only used a small amount.
I tried to keep an Oxygen free atmosphere during the melt, but when I couldn't get the heat up over 1500F, I opened the air up more than usual. I had a chunk of charcoal on top and it started burning away when I turned the air up so I knew there was more O2.

[Jammer]

I got some new cast iron molds from e bay today. They're from and old light bulb factory, a couple round bulbs and a couple Christmas flame bulbs. I'm going to try to cast some in Lead tomorrow and then do some bronze ones for fun.

[chucketn]

Pictures, please!
If you have any extra from the next bolt melt, please pour me a small lump. I'd like to see how it machines.

Chuck

[Jammer]

OK, Chuck I'm getting to go out and try the Lead. These are glass molds and have small vent holes in the sides, I'll have to pour in a pan in case the metal comes out of the holes. I think they are small enough that it won't leak but once they get hot they might. I had sinker molds shoot metal out of weird places that looked sealed.

I get some pictures.