I prepared some scrap of aluminum, so it was time to melt it. Not long time ago, I’ve made a steel mold and several days ago a cement mold. The thing that I called “a cement mould” is a mixture of cement (45%), sand (45%) and graphite
dust (10%). Therefore, I’ve decided to make 2 aluminum ingots from the scrap.
During the pouring a crack appeared in the cement mold but it didn’t effect on the bar quality. When I tried to extract the ingot, cement mold was completely destroyed.
No surprises with the steel mold. It worked perfectly.
When ingots started to cool, aluminum bubbles appeared on both of them. I’m not sure why that happened. May be that was because molten aluminium started become solid but in the center it was
still hot and liquid. It should be that I need to warm molds before casting though it may be not a solution of a problem.