Two burning (melting?) Questions on casting.

[mark_mw]

Hello all. This is my first post. I have read through the decades how to not cast with too high a temperature resulting in frosted bullets. How are frosted bullets inferior? My next question is about fluxing. If fluxing makes impurities float to the top then how can you flux if you have tin in the mix , which is lighter in weight, how will the metals mix? Thanks in advance.

[RED BEAR]

To start with i am no expert by anyones standard. The problem with frosted bullets is they may be undersize. Other than that i see no problem and use them. As far as fluxing goes use sawdust to remove impurities and a wax for combining your alloy back together. I generally clean my lead before casting and put it into clean ingots. I usually melt and flux several times until its clean. What tin or 50/50 solder i use is very clean to start with but i still flux it seperate. Then mix the two for my casting alloy after this i use wax to keep it mixed. One thing i will say it ain't rocket science. I know some will argue but a little difference in temp hurts nothing as far as i am concerned. I don't say wide swings but 50 degrees 25 up or down to me makes no difference. Anyway once you start you will be hooked and there's no going back. As i say i don't claim to be any kind of expert so take the advice for what it's worth. And please ask anything your not sure about someone will most likely be able to give you an answer.

[mark_mw]

Thanks I have plenty of sawdust and wax, will use them for my next session.

[country gent]

true fluxing blends the metal and alloys into a homogenous mix that is one metal and removes the impurities like dirt steels and other things. Most use a mix of wax and woodshavings /sawdust for fluxing. when done you should see a black ash gloating that is removed. Depending on what Im doing I may flux twice before removing the dross. Storing while the flux is present is important, pull the metal up thru it and push the flux down thru the metal scraping the sides and bottom as you go. Once an alloy is blended and fluxed it is hard to separate them. Be prepared when fluxing as the wax wood chips will ignite and burn producing the carbon and oxygen barrier that is needed. Tin and antimony arnt impurities but are alloys used to improve hardness and flow

While frosted bullets may measure to size the surface isn't the same as a nice cast bullet. Its more a hills and valleys type surface. ( some powder coating like this claiming the baked on coating adheres better) when bullets are frosted the surface is "softer" and may not seal as well. Frosted may vary in weight more.

A good thermometer and attention will help with being in the right temp range and this isn't locked in stone as different moulds alloys mould material and designs may want slightly different temps or casting cadence.

[lar45]

My take on frosted boolits...
When lead cools slowly, it gets frosty.
If you get driving bands that don't fill out completely then the rounded corners can be frosty.
So... Maybe we it started out as watch out for frosty bullets because they had frosty spots? Then someone started saying that frosty bullets are bad?
If the whole bullet is frosty and filled out completely, then I think it's fine as long as they're all the same.

[Wayne Smith]

Tin separates through oxidation - exposure to oxygen. I cast with ladle and pot, thus have a lot of oxygen exposure in my casting. I will flux a couple times in a casting session with wax. I use sawdust to clean alloy, usually when first melting random pieces of lead.

[waksupi]

I purposely cast for frosted bullets.

[mehavey]

-"Frosted" bullets are a function of [high] casting/mold temperatures, and have nothing to do with lead impurities
- High[er] casting/mold temperatures tend to produce [slightly] smaller-diameter bullets.
- If the frosted-bullet is still in the desired range so as to size properly -- the frosted bullet shoots just as well.accurately as a non-frosted bullet

See http://castboolits.gunloads.com/showthread.php?168712-Broken-Bullet-something-I-ve-never-seen-before ...all the way to the end.

[tankgunner59]

If you have a good reloading manual read the instructional section in the front and this is all explained.

[kevin c]

I also want to see frosting on my casts. When I consistently see an even light matte surface I've found that with my molds (Aluminum MP 8 cavs) and alloy (95-3-2), I get the best fill out.

If you drop a bar of tin on top of a molten lead alloy, it will certainly float until it melts. But once mixed in, the tin atoms will disperse evenly throughout the alloy and will not separate back out by density, regardless of whether the mix stays molten, freezes or is remelted.

My understanding is that most metal oxides are lower in density than the elemental metals, and, more to the point, they'll only form in contact with air, IOW, on top of the melt, so that's where you're going to find them. Reduced by sawdust or wax, the newly reformed elemental metal reenters the melt. Stirring may speed that up, and also helps the flux materials contact more of the melt and adsorb (I think that's the right word) other impurities that may be mixed in.

ETA: oh, and welcome to the madness ;^p