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View Full Version : Fluxing to keep the tin from separating: really?


Elkins45
March 24, 2010, 10:08 PM
I've read a bunch of older books on casting that tell me I need to keep fluxing my alloy to prevent the tin and antimony from separating out on the top.

Really? Then why does my pot look exactly the same when I'm casting with pure lead as it does when I'm casting with pure linotype melted directly from printer's slugs so hard they ring? I get a thin layer of oxide on both once I've been casting for a while.

Everything I know about chemistry tells me lead and tin and antimony make a true solution when melted together, just like sugar and water. You don't have to flux your kool-aid once you mix it, do you?

Your thoughts?

snuffy
March 25, 2010, 12:53 AM
Elkins, you're entirely correct! Lead alloy is a true metal solution, nearly impossible to separate. I say NEARLY impossible, I suppose there's some chemical way to make the components separate, but why would you WANT to?

If the people that say you must constantly flux to keep them combined were right, all you'd need to do the get pure lead is to put an alloy in a pot, melt it, then let it sit for a day. Then come back to skim off the tin, antimony and other trace elements. It doesn't happen!

Their theory is; the tin and antimony are LIGHTER so should float out when they're liquid. If the alloy wasn't a true alloy, or in other words, a solution, it would work.

It's an often repeated myth, by people that don't actually engage their brain.;)

salvadore
March 25, 2010, 03:11 AM
I only reflux ( sounds like an upper GI problem) if I add metal. I recently read in the Fowling Shot, or LASC, or reloader, or somewhere that that's all you need to do.

IllinoisCoyoteHunter
March 25, 2010, 06:52 AM
I am not a big fan of fluxing, but still manage to get beautiful bullets that shoot great. I must be doing something wrong??? ;)

I flux when my melt reaches casting temp and sometimes when I add ingots to the pot.

GP100man
March 25, 2010, 09:17 AM
I triple flux when I make ingots, Imean I really work at stirrin to get stuff on top !!!

Then in the bottom pour I flux again to get the oxidization to the top & I leave it there to seal the top from oxygen, may even throw in a pinch of saw dust in if I have it !

& I flux with parrafin or left over smell good candles !
The bonnified flux materials are extremely hydroscopic & leave a coatin of crude on everything.

chris in va
March 25, 2010, 09:04 PM
Not sure what it is, but after a while I get this golden colored sheen on my melt. It's not the same as the usual oxidation. After I flux, it goes back to silver.

hornady
March 26, 2010, 02:22 PM
Snuffy is exactly right, One of the best resources on fluxing is also the cheapest. The Lyman cast bullet book, It details the effects fluxing has on alloy mix.

totalloser
March 31, 2010, 10:45 PM
My guess is that conventional wisdom is usually right. You don't need to flux your koolaid... keep in mind what happens when you have a thicker mix-it crystalises on the surface. Rock candy. The flux also is said to help prevent (or reverse) oxidation.

I don't know much about chemistry, but I would pause before making assumptions that differ from conventional wisdom.

David Wile
April 5, 2010, 06:59 PM
Hey folks,

I have been casting bullets for 50 years, and it has been pretty much based on what I learned from the Lyman Cast Bullet manuals that recommend frequent fluxing. I am not, however, a scientist, and I admit that I do not understand the dynamics of what is going on in my lead pots. I do pay attention to what is going on with my melt as I do my casting, so what I have to say is from my own empirical observation rather than learned science in metalurgy.

I cast some bullets with virgin lead, but most of my bullets are cast with an alloy of lead, tin, and antimony. In his first post, Elkins said the top of his pot looks the same whether he is using virgin lead or a linotype alloy. When I have a pot full of either virgin lead or alloy that is up to casting temperature, I flux both materials first to remove any dirt from each type, and second to keep the tin and antimony in the alloy. I agree with Elkins that after casting a while, the top will dull to a grey color which I think is oxidation at the top. However, after casting alloy bullets for a longer time, the color of the top changes from dull grey and begins to take on a somewhat golden sheen which, based on what I have always read in the Lyman manuals, I assume is the tin and/or antimony coming out of the alloy. At this point, I re-flux the melt, remove any dirt, and of course the top is bright silver again.

I do not get the golden sheen on the top of virgin lead no matter how long I cast, so I do not bother to flux when casting virgin lead.

Like I said, I am neither a scientist nor a metalurgist, but my observations in my experience casting seem to fit right in with what I learned in the several Lyman Cast Bullet manuals I have purchased over the past 50 years. I also have a manual written by Veral Smith. While I do not remember exactly what Smith states in his book, I also do not remember anything he said that discounted what the Lyman manuals state.

Best wishes,
Dave Wile

hangfirew8
April 19, 2010, 09:16 PM
Gold is oxidized alloy, if you get it while smelting lead you're too hot, while melting Wheel Weights your temps are way too hot. If you get it while casting, you have to ask yourself if you really want to run that hot, maybe you do.

-HF

Edward429451
April 19, 2010, 09:45 PM
I flux when it appears to need it wether dull grey or gold. I see the gold more often when smelting ingots rather than casting.

GP100man
April 20, 2010, 11:44 AM
Could the gold color be some trace copper in the melt , I do see a number for copper on some tin sources ?????

I run fast & hot , up to 775f & have never seen the gold , matbe not hot enuff , empty the pot too fast????

I have seen it when ingotizin & blendin though & temp was the same ????

Just thinkin out loud :confused:

After castin a batch I check BHN with a lee tester & get the same all thru & I flux a full pot (10# lee bottom pour)& don`t stirr no more until I refill the pot .