Annealing in a Casting Pot?

jethunter

jethunter

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This quite a good article on annealing brass: http://www.annealingmachines.com/how-to-anneal.html

...Changes start to occur in brass grain structure at 480 degrees fahrenheit. To properly anneal brass, the temperature needs to be at 650 degrees F. for several minutes--BUT this will transfer too-much heat to the lower case in that time. So we need more heat for a shorter time. We need to raise the neck temp to about 750 degrees F. only for a few seconds to anneal...
Click to expand...

I stumbled onto this article today and it reminded me of an idea I've ruminated on for several years: Has anyone used molten lead in a bullet casting pot to anneal brass?

Since I already had a pot of lead melting I gave it a try just to see what would happen. Used some 1F 30-06 brass picked up at the local range.

My casting pot was full of molten lead and thermo reading 750F. I used a piece of wet paper towel doubled over mulitple times wrapped around the case from 1/4 below the neck and covering the rest of the bottom as a heat sink. Wearing leather gloves, I held the case inverted and dipped the neck into the molten lead, counted to 5, pulled it out and dropped into cool water. The portion of the brass that entered the lead turned colour slightly - a rainbow sheen that wasn't there before, and just slightly darker. No lead stuck to the brass internally or externally. I did a half dozen cases and varied the dip from 3-6 seconds. No real difference noted from the different immersion periods.

It is very simple and easy. If it actually is annealing, I could easily do 100 brass in 20 minutes with very little effort and no additional expense or equipment than what I already own.

I haven't done any testing to check the brass before or after the treatment. Now that I know it's possible I'll do a bit more thorough trial down the road. Thoughts?
 
One drop of water from your wet paper towel touches that lead and you would have an explosion.
Just a word of warning but you already know that.
 
Using molten lead is described in at least one article I have seen, if you look you might be able to find it. Cant see 3-5 seconds being long enough. Have heard of doing it that way from old timers but no details.

I have a portable induction heater at work. I may give it a try once I find some tempilaq. Anyone have a source that I might find in buttfuknowhere?
 
Got this off Long Range Hunting Forum:


"Ok, my process isn’t high tech or anything.
I bought a cheap lead melting pot, and melted in a few big fishing sinkers from Walmart.
This is not very pure lead, so contaminants form at the top during use. I skim this out with an old screwdriver.

With pot temperature adjustment, I use an old Omega thermocouple/indicator inserted in the lead, and have verified it’s readings with a handheld laser thermometer(borrowed from work). I set temp at 675deg highest, which can drop as low as 600deg depending on the rate I’m dipping cases. With each dip some heat sinks away to the case, and the cheap built-in controller raises temp to compensate -with a bit of overshoot.
So my window is ~600 to 675deg.
This recrystallizes(stress relieves) the case both from the inside and outside, without risking annealing.

Before lead dipping I pour Mobil1 oil in a plastic ammo box and insert my cases mouth down into it. Then I stand the cases up on a nail board with paper towels to further drain. Nice thin layer.
I’ve tried many oils/coatings and Mobil1 is the only coating I know of that can withstand these temps long enough, and not seperate from the cases during dipping. Amsoil synthetic might work, I don’t know. Don’t even try the other synthetics available, they’ll just burn off with a flame, and you’ll pull an elephant foot out permanently affixed to your case.
Even Mobil1 eventually burns. But it takes a couple minutes, and is not an issue provided you keep the amount low(hence, thin layer).

To dip, I just pick up a case with a leather glove and very slowly lower into the lead(maybe 1/8” per sec), and once reaching my desired point, I raise the case back out at the same rate. Very slowly. The oil forms a ring that flows up the case away from the surface of the lead pool. This leaves just enough of something(surface oxidation?)on the brass to keep lead from soldering to it. The case feels dry afterwards, -where it contacted lead. But if you go too fast with inserting or removing, this coating fails to form and lead sticks.
For new 6.5WSSM brass I needed to form new body taper & shoulder angles on, I timed 45sec total dip for stress relieving to center of the case bodies. Slowly In/slowly out in 45sec. My wife helped me measure caseheads while doing so, and we get less than 200deg. Brass is unaffected below 450deg, so I’m confident in the control offered by lead dipping(over any other method). You could not easily go so far down a short case with a torch, without ruining it.
For simple neck/shoulder with normal thickness brass, you could probably hold the caseheads with your bare hand.
Completed dipping, I drop the cases in a pan of Citrisolv, or whatever degreasing agent provided for me in the kitchen. Then I tumble. The brass darkens only slightly where stress relieved. Less than factory discoloration.

People rule out lead dipping due to risks with fumes and the evil energy in that pot. They rationalize that torching is easier –therefore better? Why is easier always better??
Annealing begins ~900+degs. How do you know a torch has produced the correct temperature all the way through the brass, and not 1000deg on the outside and 200deg inside?

Anyway,,
I dip outside with a box fan behind the pot, pointed down wind. Lock away any cats or dogs beforehand, and just be careful not to dump the lead or drop anything into it. Pretty much the same precautions needed with a torch.
Overall, it’s less painful than turning, and about the same pain as bumping.
I only stress relieve when needed. I know when I reach this point because I comparative measure & watch neck tension, and when bumps fail to consistently hold, it’s time. With the minimum sizing I do, I can easily go 10 reloads before re-dipping. With the 6.5WSSM batch referenced I am just at this point(26 reloads).

That's it!
And with this you could apparently walk among Supermen.."
​
 
As well, if you leave the old primers in, the case is airtight, and no lead will flow up inside the case.. any stuff that does stick on outside typically wipes off with a leather glove..
 
He says annealing begins at 900 degrees but his pot is only set at 675 and your at 750. What is best annealing temp? I've done it for decades and never had a problem but I like the control using a pot of lead.
 
juanvaldez said:
Got this off Long Range Hunting Forum:


"Ok, my process isn’t high tech or anything...Before lead dipping I pour Mobil1 oil in a plastic ammo box and insert my cases mouth down into it. Then I stand the cases up on a nail board with paper towels to further drain. Nice thin layer.
I’ve tried many oils/coatings and Mobil1 is the only coating I know of that can withstand these temps long enough, and not seperate from the cases during dipping... nd you’ll pull an elephant foot out permanently affixed to your case.... reaching my desired point, I raise the case back out at the same rate. Very slowly. The oil forms a ring that flows up the case away from the surface of the lead pool. This leaves just enough of something(surface oxidation?)on the brass to keep lead from soldering to it. The case feels dry afterwards, -where it contacted lead. But if you go too fast with inserting or removing, this coating fails to form and lead sticks...
Click to expand...


I didn't use lube and I didn't have any problem with lead sticking to the case. Probably for the same reason that lead doesn't stick to a ladle - it's hot enough that it doesn't freeze the lead.
 
big boar said:
He says annealing begins at 900 degrees but his pot is only set at 675 and your at 750. What is best annealing temp? I've done it for decades and never had a problem but I like the control using a pot of lead.
Click to expand...

click on the link in the first post, it has a decent technical writeup on the temperature ranges and effects.
 
thump_rrr said:
One drop of water from your wet paper towel touches that lead and you would have an explosion.
Just a word of warning but you already know that.
Click to expand...


It was damp, not dripping. "explosion" is a bit of an exageration although it can still burn you. Regardless of what you're doing with molten lead - use eye protection and gloves at minimum.
 
thump_rrr said:
One drop of water from your wet paper towel touches that lead and you would have an explosion.
Just a word of warning but you already know that.
Click to expand...

only if the water gets under the lead, otherwise it just boils off.

i've come to realize over the last year or so that mixing water with molten lead is over hyped which isn't necessarily a bad thing, but it's not going to instantly spray lead all over the place.
 
+1

I get water on the surface of my lead while casting all the time and it sizzles and that's it. I even put sprues and miscast bullets back in the pot wet; I just make sure I lower them slowly so no water is trapped and forced under the surface. I've had a single little lead explosion and it was while melting a dry ingot. After a minute or so the lead pot just burst and sprayed about 6" in the air. I guess there was a pocket of moisture or something inside the ingot.

I always shake my head at people who claim that if a single drop of water gets in a pot of molten lead it will cause a huge explosion. Been there, done that dozens of times, nothing serious happens.
 
LUTNIT said:
+1

I get water on the surface of my lead while casting all the time and it sizzles and that's it. I even put sprues and miscast bullets back in the pot wet; I just make sure I lower them slowly so no water is trapped and forced under the surface. I've had a single little lead explosion and it was while melting a dry ingot. After a minute or so the lead pot just burst and sprayed about 6" in the air. I guess there was a pocket of moisture or something inside the ingot.

I always shake my head at people who claim that if a single drop of water gets in a pot of molten lead it will cause a huge explosion. Been there, done that dozens of times, nothing serious happens.
Click to expand...

Exact same experience for me.

On my first batch of cleaning up lead to make ingot's I would drop the ingot's into water once they hardened up a bit. When I put them into my lee pot they would start to hiss and bubble. Water must have been sucked into the ingot as it cooled. I let them air dry now.
 
Annealing brass starts at approximately 650-700 degrees Fahrenheit. 900 is way too hot.
Dipping stuff in molten lead seems like a whole lot more fuss than running a propane torch. Brass cases need to be heated until they change colour and no more. Red hot is too hot.
No W's. bisonballistics.com/articles/the-science-of-cartridge-brass-annealing
 
What about using one of the "heat transfer fluid" (oils) used in high temperature heating systems?
I know Sun 21 heat transfer oil has a max. film temperature of 650f @atmospheric pressure, Monsanto oils will run at 750f.
Google "heat transfer fluid", it might work if you can buy it in small qauntities.
 
LUTNIT said:
Wouldn't molten salt be way too hot for brass? It's used to anneal and heat treat steel.
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Can't do a good search from work, but :

http://www.ksccw.com/showthread.php?t=55452

Post # 5 has some info.
there is many different salts that melt at different temps, additionally it's also a factor of time.
IE: (not actually times) 3 seconds at 700 deg or 0.5 seconds at 900 deg.

salt is commonly used to heat treat, but also annealing.

sorry about the scrappy reply layout... cellphone.
 
Should work but seems like a lot of bother.
I'll stick with my propane torch and cordless drill. Spin the cases until they start to turn blue, then drop them into an empty dish. The base gets hot but not hot enough to anneal. Have done this for a couple thousand rounds now I guess with no problems encountered.
 
The melting point of potassium nitrate is about 330C, almost the same as pure lead. It can be depressed by mixing in some sodium nitrate. I have annealed thousands of cases using a Lee melting pot and potassium nitrate. The temperature control is unbeatable, and it is fast: 1000 cases per hour is easily achievable with my setup. It's a pain to setup for only a handful of cases, but if I need to do a hundred or more it is absolutely worth it.

I have been showing this video on this and other shooting forums for years:
http://vid262.photobucket.com/albums/ii102/BattleRife/Saltbathannealingdemo2.mp4

Although the speed is nice, the real reason I worked on this method was the control of annealing temperature. I looked at the usual sources of annealing information, such as published manuals and the online 6mmBR article, and decided I didn't believe any of those authors had much credibility when it came to the temperatures they recommended. So I setup an experiment and determined a temperature on my own. Five seconds at 600C did the trick. This is of course much hotter than almost anyone has published, but it is worth noting that it is still below the threshold of luminescence.
 
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