Does Lead "Boil"?

[jim4065]

I'm not thinking of turning to a gaseous phase as such, but when melted, do the atoms of lead and alloyed metals circulate in the fluid, thus mixing themselves over time? I'm thinking of the currents that you see in water (even before it boils) and wondering if the same thing happens in the lead pot once the lead becomes liquid. We don't stir salt water once the salt is in solution so why stir the lead? Why don't the lighter inclusions (such as iron) just automatically bubble to the top? :?:

[ANeat]

The crud can get trapped, stuck to the sides of the pot etc.

Also any crud just doesent float to the top like a cork in water.

Give it a good stir and flux, if your bullets are good I wouldnt worry about it after that.

If youre getting inclusions in the bullets then you need to stir/flux more

[ANeat]

Oh yea, yes lead boils at 3180 degrees F

That would make a frosty bullet :0

[462]

The very weight of lead will cause dirt and other impruities to become trapped against the sides and bottom of the pot and not get caught up in the current. Stirring and scraping allows them to become mobile and float to the top. I've experienced wheel weight clips becoming trapped on the bottom of the smelting pot.

[Rocky Raab]

This is one of those "yeah, but" answers.

Lead does boil, but what the OP refers to are convective currents. Yes, lead has those, also. But (there it is!) lead is so dense that those currents don't behave at all like ones in water. It is entirely possible for the downward convective movements of slightly cooler lead to capture things like bullet jackets, tire clips and such, holding them under the surface.

Such items would probably rise to the surface eventually when they entered a rising current. But (there's another one!) those are slow currents, again due to the lead's density. It is far better to simply stir the pot mechanically and achieve the same result quicker.

[Shiloh]

A lot of problems in casting would be eliminated with proper scraping of the pot and fluxing.
ALL of the metal must come in contact with the flux as well as removing the crud on the sides and bottom of the pot.

Eventually, the impurities and contaminants trapped on the pot will find there way into the boolits

Shiloh

[chboats]

If someone questions the idea of crud getting trapped on or near the bottom of the pot try what I did. Had an empty pot. Put about 25 pulled, gaschecked boolits in the bottom of the pot to get the melt started (thought it was a good idea) When the pot was 3/4 full and fully melted I started fluxing. Had a hell of a time getting all of those checks out of the melt. Now I add checked boolits to the top of the melt and do a lot more fluxing before I start to cast.

Carl

[leadman]

A little off subject, but something I noticed since I made my "casting closet".
My casting closet is 3 sided, with the two sides being 6' high. The front is cut out and there is a 20" fan mounted there for ventilation. Now this is a cheap fan so it vibrates on high just a little. This vibration is a plus as it gently shakes the lead pot and actually helps the crud float to the top of the melt.
Fluxing is more productive and my boolits have never been cleaner. The inside of the pot stays pretty clean also.

[jim4065]

A little off subject, but something I noticed since I made my "casting closet".
My casting closet is 3 sided, with the two sides being 6' high. The front is cut out and there is a 20" fan mounted there for ventilation. Now this is a cheap fan so it vibrates on high just a little. This vibration is a plus as it gently shakes the lead pot and actually helps the crud float to the top of the melt.
Fluxing is more productive and my boolits have never been cleaner. The inside of the pot stays pretty clean also.

Ya know - that's a good idea! Suppose the pot were mounted on top of a vibrating plate (perhaps adapted from a vibratory case cleaner) - it might be just a matter of switching on the vibrator for a minute or two to finish fluxing the pot. My whole cabinet is sitting on an old metal tabletop - might just set the case cleaner on it and turn it on to see what happens................:mrgreen:

[geargnasher]

I ususally tap the sides of my Lee pro 4-20 a few times with the maple stick I use for stirring and scraping, helps trapped crud turn loose and float up.

As another aside, I was having trouble (since I flux with sawdust) getting little ash inclusions in my boolits and pits on the surface due to trapped sawdust ash getting stirred in and finding it's way out the spout. I thought the solution was to minimize stirring, but then I got a batch of 3/4" square hard maple ricks from my cabinet shop friend, cut them into 12" lengths, and stir the pot with them, no sawdust required except on heavily oxidized melts. You can actually watch the grey oxides disappear behind the charred rick as you stir, and the hard maple leaves very little ash, just fine carbon which gets consumed in the reduction reaction.

As I remember, Glen Fryxell commented on the circulation of lead alloy in a pot, think it was the article on Fluxing that he wrote, but could have been a different one.

Gear

[monadnock#5]

Yes, lead boils. The last time I fluxed and alloyed there was one pot where I had a bubble come up in the same spot about every 10 secs. Let it set too long while doing something else.

Another thing lead has in common with water is surface tension. With water, you can fill a glass up taller (slightly) than the sides of the glass. Try the same thing with water with a couple of drops of dish washing detergent mixed in and it won't work. The detergent breaks the surface tension.

So, I'm going to say (at the risk of being totally wrong, oh NO!!) flux is to lead as detergent is to water. Except that with lead the effects are short lived. The flux won't stay emulsified for very long before it burns off and turns to dross.

The most successful process I've come up with to date is: I 1) render WW's and range scrap (separately) in my cast iron pot where I'm not at all concerned with a little crud in the product. I then 2) alloy the WW and range lead at 2:1, weighed out, in a SS sauce pan, and here I flux and stir and skim vigorously, and clean the pot out between melts, toward the end that the ingots produced at this step are as clean and pure as I can make them, so that when it comes time to pour boolits 3) I stir and flux the pot once, when it first comes up to temp, and not again till the next session. I keep the melt covered with sawdust and/or wood ash, which I push to one side of the pot when it comes time to add more ingots.

So, to answer your question, it depends on which phase of the operation I'm in as to how much I stir. Sometimes more, and sometimes a lot less. My method is labor intensive, yes I do realize. I've never been happier withe final product however.

[armyrat1970]

Yes, lead boils. The last time I fluxed and alloyed there was one pot where I had a bubble come up in the same spot about every 10 secs. Let it set too long while doing something else.

Another thing lead has in common with water is surface tension. With water, you can fill a glass up taller (slightly) than the sides of the glass. Try the same thing with water with a couple of drops of dish washing detergent mixed in and it won't work. The detergent breaks the surface tension.

So, I'm going to say (at the risk of being totally wrong, oh NO!!) flux is to lead as detergent is to water. Except that with lead the effects are short lived. The flux won't stay emulsified for very long before it burns off and turns to dross.

The most successful process I've come up with to date is: I 1) render WW's and range scrap (separately) in my cast iron pot where I'm not at all concerned with a little crud in the product. I then 2) alloy the WW and range lead at 2:1, weighed out, in a SS sauce pan, and here I flux and stir and skim vigorously, and clean the pot out between melts, toward the end that the ingots produced at this step are as clean and pure as I can make them, so that when it comes time to pour boolits 3) I stir and flux the pot once, when it first comes up to temp, and not again till the next session. I keep the melt covered with sawdust and/or wood ash, which I push to one side of the pot when it comes time to add more ingots.

So, to answer your question, it depends on which phase of the operation I'm in as to how much I stir. Sometimes more, and sometimes a lot less. My method is labor intensive, yes I do realize. I've never been happier withe final product however.

I have to disagree in some respects but not all. Tin is to lead as detergent is to water, per your description. Tin reduces the surface tension of lead, not flux. The flux may work in conjuction with the tin but flux alone will not lower the surface tension of the alloy. I think tin will lower the surface tension of the alloy without fluxing but you need fluxing to remove the impurities and cut down on the oxidation of the tin.
http://www.lasc.us/FryxellFluxing.htm

[Bret4207]

I have found that since going to a stainless steel pot and fluxing with nothing more than a stick that my dross problems and related inclusions have dropped to near nothing. I still get dross, just not in my boolits. I think the scrubbing action with the stick and getting the carbon down into the melt rather just floating onto is the key.

[armyrat1970]

I have found that since going to a stainless steel pot and fluxing with nothing more than a stick that my dross problems and related inclusions have dropped to near nothing. I still get dross, just not in my boolits. I think the scrubbing action with the stick and getting the carbon down into the melt rather just floating onto is the key.

I have tried to stir my pot with a wooden paint stick but it is a little to large for my Lee 10 pounder. Might try just a small branch off my oak tree.
Bret. You use no other type of flux and just stir with a stick?

[shotman]

armyrat make sure the branch is dry . If its green you wont have much to stir. I dont use it in the boolit pot but I had a bout 500lbs of range scrap that had alot of sand in it {sand berm?} I found that it worked good to get the small junk out of the lead . I now keep a bucket for the WW s. It seems to like zinc, cause sometimes I will find a clump and its got a half melted wheel weight {zinc?}

[oldhickory]

I have tried to stir my pot with a wooden paint stick but it is a little to large for my Lee 10 pounder. Might try just a small branch off my oak tree.
Bret. You use no other type of flux and just stir with a stick?

Make sure you use a dry stick.

[armyrat1970]

Oh yeah. I have plenty of dried up sticks lying in the backyard. After I watch the Saint- Dolphin game this Sunday, I will give them a try. Who-Dat?:drinks: