tin and lead flow

[WhitworthNewby]

Anybody know the metallurgy behind tin and pure lead flow?
thanks

[Txcowboy52]

Welcome to the forum Whitworth ! Lots of great people and good info here. I must say though your question is way over my head .

[imashooter2]

Tin improves the wetting and spread of and lowers the solidification temperature of lead-tin alloys. That is the short answer. The how of it fills Engineering and Chemistry textbooks.

[centershot]

Glen Fryxell does a pretty good job of describing the metallurgy of the alloys we use in casting bullets. Give a look here:

http://www.lasc.us/Fryxell_Book_Contents.htm

[mfraser264]

Tin is believed to reduce the grain size of the alloy allowing for better flow of metal and the filling of smaller, sharp details, simplified version. One of the reasons Linotype cast details so well, high tin content. Lino in a couple of my RCBS moulds will show the machining marks.

[Gobeyond]

It also breaks the surface tension of lead. Which is high, causing it to flow easier, kind of thins it out a bit too.

[Bigslug]

It also breaks the surface tension of lead. Which is high, causing it to flow easier, kind of thins it out a bit too.

THIS. A good way to think of it - soap uses this same mechanism to make water work better as a solvent.

[dale2242]

What Gobeyond said. ^^^^^

[fixit]

It reduces surface tension, that tendency to bead up, or at least that's the way I understand it.

[GregLaROCHE]

When I started casting, I used range scrap that had tin in it. My boolits turned out well. Several years later I started casting pure led for mini balls. I was surprised how much harder it was to get good fill out with the pure lead. Whatever the metallurgy is, tin does make a big difference.