Fluxing help

[grisy11]

hello every glade to be on this site.
i need a little help.i have been casting boolits for 15 years on and off.do you need to re flux the cut off?i did up 18# of 9mm last night and i had a half of pot of cut offs.
thanks for any help
Grisy11

[*Paladin*]

Welcome! By "cut off's" I assume you mean the sprues? Personally, I just throw the sprues back in the melter. The haven't been introduced to any contaminants to clean out, so back into the pot they go.

[Hickory]

It's a good idea to flux fairly often.
It helps to remove impurities and
also helps to reintroduce the tin back into the lead.
Some of the dross that forms on the top of the lead
is tin and fluxing will help to keep it in the lead.

[grisy11]

yes thats what i meant.thanks what i have been doing is every time i put more in the pot i flux it and i dint know if i had to do that all the time or not
thanks alot
grisy11

[GP100man]

Well , heres my little routine , I fill the pot up let it melt & flux it deeply & twice !!

I leave the dross as a shield from oxygen , some use saw dust ,kitty litter & a layer of carbon from moter oil !!!

I cast until I get my sprue can full ,then pour em in & I feel it`s very important to flux as the sprues may pull the dross/dirt down into the mix !!!

I can usually go 1/2 a 20#er before doing this ,so it`s break time anyways !!!

Almost forgot !!!!

WELCOME TO THE CASTBOOLITS FORUM !!!!!!!!!!!!!!!!!!!!!!!!!

For your viewing pleasure !!!!

http://i746.photobucket.com/albums/xx110/GP100man/102_0523.jpg

[WHITETAIL]

Welcome to the forum![smilie=w:
What I do is to have a 1lb. coffee can next to my lead pot.
I take the sprews and rejects and throw them in the can.
And this gets smelted in a new batch which I call super clean.
This is my rifle lead.:cbpour:

[grisy11]

thanks every one for all the info.i did put some of my sprews back in and i saw some tin float on top so i fluxed it agent.what dose it mean when i start molding all 6 of the sprees cut off in a strip but after 4 or 5 # of lead thy seem Reilly brittle and dint stay together?any idea?
i have been up here reading things for 6 months now some times hrs striate this is the best site ever I'm glad to be on Bord
Thanks
grisy11

[lwknight]

The sprue only seems brittle because it is disturbed during the phase process. Non eutectic alloys will appear to be set up but still soft because some components like tin are still liquid.
We do this because letting the sprue to cool entirely would probably cause you to break your sprue plate trying to cut it.

I would not worry about fluxing the pot till the dross /oxides on top get substantial. All things in nature search for equilibrium so the tin that oxidizes on top is constantly replaced by tin from the alloy. You could eventually deplete the tin by constantly skimming the pot but , it would not be easy.
A little dross on top actually prevents farther oxidation by covering the melt.

[HamGunner]

When using a bottom pour furnace I normally use saw dust for fluxing. After the sawdust has reduced to ash, I mix the alloy well and remove any impurities with the ash flux, I toss another handful or two of sawdust back into the pot and leave it while I cast up a good portion of the furnace of alloy. The saw dust is reduced to ash again, which I think helps to prevent oxidation. Of course, if not using a bottom pour and I am dipping from the top, then I must keep a cleaner surface and I just watch the surface and when it gets a bit scummed up, I just flux again. It takes a bit longer to flux with sawdust as it needs to burn completely up, so when not using the bottom pour furnace, I usually use a faster flux such as used candles, etc. I use only enough heat to cast well as I find that excess heat can certainly increase the amount of fluxing required. By varying the speed of casting and therefore varying the temperature of the mold, I can normally find the right speed of casting to cast well without having to heat the alloy to an overly high temperature.

[JSnover]

My sprues are the first thing to go back in the pot. They're clean, they're still warm (they don't cool the pot as much as a new ingot) and they're the same alloy as the boolits I'm pouring. At the end of the session any leftover rejects, sprues, drippings, etc go back into the pot.

[steve in kc]

I do. Mostly because I cast with 2 bangers and a coleman stove and use a LEE dipper. When I get to the point to where I can't get a full dipper (I like big SPRUES and I cannot lie!) Then I find I've accumulated a big pile of sprues. Easy to have a bigger pile of sprues then boolits when you're casting C309-150-F's.

I also find at that point that I need to add more alloy.

I was having problems keeping my sprue/allow/mold at the right temp's for good base fill outs as I was having the classic problems; rounded bases, tearout's etc.

So now, I do not drop my sprues back in the pot unless I'm adding alloy. I let everything melt, throw my DROSS back in as well from the previous runs, flux twice and I'm off and running.

Ever since I adopted this method as well as adding the dross back in, I'm finding that I'm recapturing my tin and have absolutely fantastic fillout.

I made a big ol' pile on Sunday of:
C309-150-F
452-228-1R
452-200-RNFP
457-405-RNFP (single cav which the lee dipper just barely fills with an OK sized sprue)

[fredj338]

I only cast w/ clean alloy, so I flux once before casting & then when ever there is a significant dross on top. There probably isn't any magic number of times & I don't think yo ucan flux too often.

[a.squibload]

...After the sawdust has reduced to ash, I mix the alloy well and remove any impurities with the ash flux,...

I've read here that sawdust flux should be allowed to burn down real good before stirring it in.
Here's the question: would throwing ash in the pot be just as good as using sawdust?
I mean what's the difference?
The sawdust would smell good but I guess the ash wouldn't even smoke.
I mainly wonder if the ash would flux the alloy.

Our pellet stove produces lots of ash, just like a fireplace.
If I can use the ash as flux it would keep me from using the pellet fuel (saving $).
I've always used candle wax or old lube before.
Ideas? Opinions? Thanks!

[geargnasher]

What we usually refer to as fluxing is really metal oxide reduction. Reduction is the name for the chemical reaction that opposes oxidation. Ash will not help reduce oxides. The substances that reduce the oxides of lead, antimony, and tin need to provide two things: Carbon and Carbon Monoxide. Good "Sacrificial reducants" are hydrocarbon compounds like sawdust, pine pitch, paraffin, beeswax, oil, whatever you call it need to burn on the surface of the melt (in direct contact with the floating oxides) and in a melting pot the surface is typically low in oxygen, so the hydrocarbons break down during this slow, smoldering combustion leaving CO and C to react with the metal oxides by stealing their oxygen atoms and becoming CO2 gas, leaving pure metal behind. The small amount of ash remaining to be skimmed is the junk that doesn't react completely.

Kitty Litter and Marvellux are NOT reducants, they work by sealing the surface from oxygen, but do nothing to return oxides into the melt to begin with.

Gear

[a.squibload]

Thanks Gear, that's what I was getting at.
Seems like the ash is used up, will provide no hydrocarbons to reduce the oxides,
in other words, won't flux.
Ash might provide an O2 barrier, but I ladle-pour so that's out too I guess.

I buy sawdust pellets by the ton, should work fine!