Wei was still looking at the felt when Batu answered him.
"We pour the molten metal all at once."
Batu searched through his fragmented memories to explain. "If you make it in pieces, it will break where the parts meet once the pressure increase. After the pour, bury it in sand and let it cool there. Don't pull it out while it's still hot. The whole casting needs to cool evenly or it will crack. When you test it, start with half the charge you think it can take. The first failure will show you where the weakness is."
Wei set the felt down slowly. He went through each part of the advice against what he already knew before he responded.
"I know about pouring it in one go."
He said. "The joins are always the first place to break in every tube I've seen crack. I've been working toward that, but I hadn't committed to it at this size."
