Fluxing wheel weight lead etc.

[Jim..47]

I have always fluxed but with concern with what I am removing. Is it possible to remove the good stuff when fluxing, such as tin, antimony etc? If so how do I avoid this and what different process should I use? I switch back and forth between sawdust and wax, and i'm not sure if there is much difference.

If I save the stuff I remove is there a way I can test it to know for sure what it is, or maybe I shouldn't skim at all and reduce the danger of removing the good stuff?
Thanks for your help. Jim

[Jim..47]

I guess I should add that I do sometimes add in antimony and tin but same questions as above.

[GhostHawk]

My opinion, and it is just that, an opinion. Is that fluxing does just the opposite. By putting something that requires oxygen to burn on top, you create a zone that helps remove oxygen from oxidized tin which can be laying on top. Putting it back into the melt, while removing impurities.

But I save all the dross/skimmings from my pot, and it seems to me when I flux it that a lot of it goes back into the melt. So I don't flux my pot often, but I save all that stuff and reclaim what I can when I am smelting a batch.

If I am wrong I am sure someone will show up shortly to say so.

[Recaster]

I don't completely understand the physics of it all but the way I understand it is... the flux/sawdust removes the impurities and the reducer/wax helps keep the good metals in the mix. Probably will get a better answer but this is my understanding.

[Yodogsandman]

Here's a good article on fluxing. More recent testing has confirmed that the material that you skim from the top does not reduce Sn or Sb in your alloy by any measurable amount.

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

[country gent]

Fluxing for me depends on wether Im smelting or casting Ill give bothe here for you Smelting 2-3 (sometime 4 if melt still has dull dirty look) then ounce with paraffin or wax. Stirring and working lead thru the wood chips sawdust and the wood chips sawdust down thru the mix. Same with the parrafin wax. when done and impurities are off alloy is a mirror finish. I dont add any extras till base metal is clean, then flux one more time with wax paraffin. Casting with the small lyman pot its bullet lube wax or paraffin when needed stiring and scraping the sides and bottom of pot. On my big casting pot I use a mix of wood chips sawdust with wax or paraffin stirring and scraping sides and bottom of pot to loosen crud. As long as you flux 1 or 2 times before removing crud most should be reclaimed into the mix I only skim after fluxing.

[Cleve Branch]

Reading from the Lyman third edition tin and antimony once melted into lead can not be removed. Literally dissolve in molten lead to form true,stable solutions. Except oxidation or electrochemical potential,once the solutioning has occurred, there is no force,gravitational or otherwise witch can seperate the constituents.

[bangerjim]

Reading from the Lyman third edition tin and antimony once melted into lead can not be removed. Literally dissolve in molten lead to form true,stable solutions. Except oxidation or electrochemical potential,once the solutioning has occurred, there is no force,gravitational or otherwise witch can seperate the constituents.

Sb and Sn do come out of solution - - - by oxidation! What do you think that gray gunky stuff is on the top of your casting pot? You can loose a lot of Sn thru oxidation and high heat. BUT...........you can reduce it right back in using beeswax. Like magic!

When re-melting dirty wheel weights, you clean and flux with pine sawdust. And most of that carp you skim off is of little value. Unless you have hundreds of pounds of the garbage....you might get a pound or two of "mystery metal" out of it if re-melted. I just throw it away. Not worth the time, effort, or $$ to try and salvage so little unknown metal.

But do what you want....if you are THAT desperate for Sn! You will end up with something you have no idea what it is. And just re-melting it in "the next batch" as some say they do, is just adding dirty filthy gunk right back in to cleaner metals and creating more work and mess for very little, if any, gain.

banger

[wadcutter]

At work we have a wave solder machines with pots carrying a couple thousand pounds of solder. We remove tons of dross a year, and check the alloys monthly. It is very rare that we have to adjust the alloys, and when we do it's because there is slightly too much copper (which comes from the boards). In short, I wouldn't worry about the alloy percentages changing much.

Fluxing reduces rate at which the alloy oxidizes, and so reduces the loss of "good stuff".

I must say the use of sawdust as a flux never appealed to me as someone who has sat through lectures on safety and has had to have blood drawn to monitor lead levels. The smoke from sawdust inevitably carries with it some amount of lead. Fluxing with fluids which vaporize (rather than smoke) is much safer.

[dondiego]

Not much different from vapor or smoke except that you can see smoke.

[wadcutter]

Not much different from vapor or smoke except that you can see smoke.

Completely wrong. Flux vapor is the volatile elements from the liquid flux (which are not really good for you, but don't contain heavy metals). Smoke is particulates, including quite a bit of lead. It is the difference between distillation and burning.

If you like using saw dust, feel free. As someone who has worked in electronics manufacturing for 25 years it seems unsafe to me.

[dondiego]

So you are saying that flux vapor does not contain lead but the burning smoke from sawdust does contain "quite a bit of lead"?

[gwpercle]

After melting wheel weights and fluxing ( I use the horrible Marvelux ), stirring the melt well to get the flux down into the metal, the stuff that comes to the surface, besides metal clips, looks like black / dark grey slag. No metal at all. I use a big stainless steel cooking spoon that has holes in it, strainer spoon ? the slag stays in the spoon the molted metal goes back in the pot.
There's nothing in the slag to recover, it's mostly dirt. Might want to try that nasty Marvelux for smelting....easiest thing I've found to use.
As for things being bad or good for you ....the only thing that might be good for you might be celery ! Other than that , everything's bad for you.
Gary

[Jim..47]

Flux vapor is the volatile elements from the liquid flux (which are not really good for you, but don't contain heavy metals). Smoke is particulates, including quite a bit of lead. It is the difference between distillation and burning.

If you like using saw dust, feel free. As someone who has worked in electronics manufacturing for 25 years it seems unsafe to me.

Trying to understand for sure. Are you saying a good way of smoking my mold is to flux my melt and hold the mold over the smoke that come up, including when it catches on fire?

I really appreciate all you guy's help. Thanks a bunch.

[wadcutter]

Trying to understand for sure. Are you saying a good way of smoking my mold is to flux my melt and hold the mold over the smoke that come up, including when it catches on fire?

I really appreciate all you guy's help. Thanks a bunch.

No not really. Smoking a mold is a separate issue really.

I was just saying I don't like to use saw dust for smelting or casting as the smoke contains particle of lead. Smoke, by definition, is solid particles floating in the air. In the case of saw dust, the smoke is mostly carbon but some lead oxide will be carried up with the carbon. Because it is easy to breath these particles into your lungs, you can get a lot of lead into the blood stream in a short order. You can't wash your lungs with soap and water after you're done casting.

By comparison flux vapor is formed when the liquid changes phase into a gas. In this process the lead is left behind (because lead can't cling to a gas the way it can to a solid).

At work I've seen exhaust vents so full of congealed flux that it dripped to the floor. We checked it with the XRF gun to see it it contained lead and it was Pb-free.

Of course if you burn the flux, and produce black smoke, you are producing carbon smoke which probably contains lead.

Generally when I smelt I will include some no clean solder paste (I have access to scrap paste and it contains an excellent flux which neither burns off or ignites at high temp.) It keeps the molten top of the pot nice and shiny and can be removed with a paper towel very easily. If I had to buy flux, I'd try some no-clean tacky flux which is designed for high temp rework.

While I enjoy much of the history that goes along with boolit casting, when it comes to safety I don't compromise. Modern fluxes are just so much better and safer than any wax or saw dust. That being said, if they work for you then by all means stick with them.

[Jim..47]

Thanks wadcutter

I am a lean mean casting guy, which means I will try to keep my costs down as much as possible. So what can I safely use to flux with other then buying a special flux. Is plain wood saw dust Ok, or news paper or what would work. I ask because I just got another Lee mold and have another on the way, and of course I want to do it right. If I can do it right only by buying flux, what names can you give me and where might I find it locally so I don't have to incur shipping charges.

You guys are a wealth of info. Thanks Jim

[bangerjim]

You smoke a mold with either a beeswax candle (best I have found period) or a butane lighter. NOT holding it over a smoldering lead pot (OMG)!!!!!!!

Just use anything that is carbon-based~! Some (and I have never figured out just why!) use old used black stinky smelly motor oil. A very simple thing to find & use is pine sawdust. Everybody has a saw and can get a pine 2x4 at the big box, right? Cut it up and save the sawdust. Or get pet bedding at walmart. Do NOT use the free sawdust from the cutting area of a lumber yard as it contains lots of other "stuff" than just wood!!!!!! Free is never free.

Read the lasc.us documents on casting.

banger

[blackthorn]

wadcutter--you said---"At work I've seen exhaust vents so full of congealed flux that it dripped to the floor. We checked it with the XRF gun to see it it contained lead and it was Pb-free.

Of course if you burn the flux, and produce black smoke, you are producing carbon smoke which probably contains lead".

What am I missing here? If the flux was tested as "lead free" using the XRF gun---where would/could the "lead" come from when you burn that same flux? Not trying to be smart-alecky here, inquiring minds want to know.

[wadcutter]

When you burn flux, or anything, it create particles of carbon. Those particles can carry lead oxide off the top of the solder pot. When flux vapor comes off, it is a gas, and in the gas phase it cannot carry solids. It's actually very hard to burn industrial soldering fluxes. Of course this is by design as that would be very hazardous.

I've never intentionally created smoke on a solder pot to test out the theory, but there have been well documented cases that demonstrate the high lead levels in people who do work with burning circuit board in the component recycling business.

[bosterr]

This question is mostly for bangerjim, but anyone else can chime in. I use paraffin to flux because it's easy for me to find, but you like beeswax. Is there something in beeswax that makes it a better choice?