
Originally Posted by
ESjaavik
No. You can recycle old castings. Don't user other aluminum. Don't let melted aluminum come in contact with iron! (So a steel melting pot is no good). To get good fluidity and avoid porosity use degassing briquets. Not Tetrachlorethane, the ones used now are much less harmful.
Don't let aluminum "stew" in the furnace. Melt, degas, skim and pour as soon as you get up to casting temperature.
Old automobile heads and pistons are fine. Try not to mix them, the outcome is unknown if you mix different aluminums.