Fairly new guy to casting here, and I suspect this has been discussed, and I did a search but didn't find what I want.
Question: If you have a bottom-pour pot of molten alloy at around 700°F with lead, tin and antimony in it, will the three metals tend to stratify (maybe according to their density) or otherwise separate if you don't stir the pot from time to time?
The reason I ask is, I just cast a couple of batches of boolits, and some came out frosty, and others came out shiny. (I haven't checked them for hardness; I'm still learning about that.) Is this more a function of the temperature of your melt and your molds, or is it due to the heavier metals coming out first and the lighter metals coming out later ... or both?
If it matters, I was using about 7/8 range scrap with about 1/8 foundry type (by weight) thrown in.
To add a few more variables to the mix, I was also using new molds ... an aluminum N.O.E. and an aluminum Lee. I cleaned them well and degreased with brake cleaner, then sooted them with acetylene. Was also careful to lube them with 2T oil following the instructions I found here on this great site.
Thanks in advance for any information.