why quench in brine?

[yammerschooner]

Over at glocktalk the following question was asked, and I am shamelessly copying it to here because I am guessing I may get a quicker answer from a broader range of casters. Here is a link to the original question at GT...

http://www.glocktalk.com/showthread.php?s=&threadid=471220


(beginning of question)
I have quenched cast bullets in water, but I have not known about quenching them in a brine solution until now.


"quote:
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but this waiting period is unnecessary if the slugs or balls are quenched suddenly in the water or in the ice-cold brine. (A solution of common salt and water, made for brining of the meat or fish. The brine is concentrated enough, when an uncooked potato floats on it). This is an old trick known by the bullet casters a century ago, but no more found from the cast bullet handbooks, written by some Engineers Graduate. Hardening of the steel is based on that same process
--------------------------------------------------------------------------------



*source* (http://guns.connect.fi/gow/arcane2.html)

Anyone here familiar with this technique? Can anyone explain why an ice-cold brine solution would be better than water?"

(end of question)


Like the original poster, I have been using a bucket of cold water. What is the purpose of the added salt?

I hope I haven't committed some kind of faux-pas by copying and pasting this question from another board. It just seems that one of you might be more familiar with the theories behind it.

[Goatlips]

yammerschooner, salt water has to be colder than 32 degrees to freeze, so my guess is simply that you can drop your slugs into colder water. Guess you'd have to keep it in the freezer, but they'd certainly cool off faster. Same deal with brake fluid as mentioned on the glocktalk board.

Goatlips

[waksupi]

[QUOTE


"quote:
--------------------------------------------------------------------------------
but this waiting period is unnecessary if the slugs or balls are quenched suddenly in the water or in the ice-cold brine. (A solution of common salt and water, made for brining of the meat or fish. The brine is concentrated enough, when an uncooked potato floats on it). This is an old trick known by the bullet casters a century ago, but no more found from the cast bullet handbooks, written by some Engineers Graduate. Hardening of the steel is based on that same process
--------------------------------------------------------------------------------



*source* (http://guns.connect.fi/gow/arcane2.html)

Anyone here familiar with this technique? Can anyone explain why an ice-cold brine solution would be better than water?"

(end of question)

This is one I have meant to experiment for several years, but have always forgot to add the salt to the water, before quenching. I do know it makes a difference with steel, and should ask my old blacksmith master the principles, as he is getting pretty old, and it is more knowledge that should be saved. I may call him tomorrow, and ask.

[Buckshot]

.............A brine solution freezes at a much lower temp then freshwater, but I don't know what the application would be at room temp. And if you added ice, it would never get colder then the temp of the ice.

For tempering steel, if I remember correctly the salt in the water aids in the reduction of steam bubbles on the steel's surface. This allows the steel in cooling faster.

I read someplace that H&R's practice for thier color casehardening was to make a saturated solution of potassium nitrate using distilled water. Then to float a layer of light oil on the surface, then to cause the mixture to roil, via blowing compressed through tiny holes in pipes laid along the bottom of the tank.

Possibly the H&R thing was to introduce some amount of nitrate into the skin of the steel, or it may have been just a wetting agent?

I found this:

".............Brine
A faster quench than water is brine. In some steels that have a low hardenability it may be necessary to go to a brine quench. Brine solution is made by adding salt, sodium chloride, to water. The backyard rule of thumb is to add enough salt to float an egg and can be varied from between 5% and 12% sodium chloride to water. The effect of brine on the quench is to make the water more efficient by precipitating on the steel and then blowing off very rapidly creating rapid agitation and disrupting the vapor jacket.


..............Buckshot

[NuJudge]

Granted, it was 25 years ago, but my Metallurgy Professors at the University of Michigan said that the advantages of Brine as a quenching medium had to do with slower formation of bubbles, so more heat transfer from the quenched item to the fluid.

CDD

[David R]

I only know about quenching steel. Using brake fluid, Used motor oil, Transmission fluid, Gear oil............. The different viscosities change the cooling speed once the item is quenched. Obvously these change the hardening of the item. The idea of used motor oil is the carbon can get into the steel and make it harder. It also makes it more brittle.

Heat a leaf spring with a torch till its red. Turn off the Oxygen and hold the acetlene flame on the spring while it cools. The leaf will now break easily.

SO in my opinion, the brine should make the boolit seem harder, but it should also be more brittle. Like said above, it lowers the freezing point and increased the boiling point. The boolit should quench faster.

David

[Vegas Vince]

I have quenched cast bullets in water, but I have not known about quenching them in a brine solution. Can any one tell me the difference in hardness?

Vince

[cropcirclewalker]

The last two days I have gone out onto my basement backdoor slab to cast some boolits.

I turn on the lead pot.

I pick up the 5 gallon bucket and carry it over to the edge of the slab and slide the block of ice out of it onto the ground.

Both times I have said to myself, "Cheese, I bet the water in that bucket is colder than that which I get out of my faucet. Too bad it is so hard."

I have tried dropping the boolits onto the ice in the bucket, but I feel uneasy about deforming them.

I think I can see why a guy in my circumstance would add salt if for no other reason than that I don't have to keep filling up the bucket with warm water when cold (outdoor) water would be colder. [smilie=s:

[Doughty]

If I understood and re-call correctly, both Bill Ferguson (the Antimony Man) and Veral Smith say that quenching LEAD in room temperature water works as well as anything. I can't explain the mechanics of it, but my own testing has backed this up.

[felix]

Vic, that's correct. It's the air jacket around the boolit that causes the slowing of the quench. Quench speed is what we are after. We need a liquid that does not boil when a boolit is dropped into it. If it boils, the boiling point is the final temperature of the quench. So, it makes no practical difference in final hardness of the boolit should the stationary water be 200 degrees or 32 degrees. Notice the word practical. ... felix

[yammerschooner]

"If it boils, the boiling point is the final temperature of the quench. So, it makes no practical difference in final hardness of the boolit should the stationary water be 200 degrees or 32 degrees. Notice the word practical"

Thanks. This is exactly how I needed it spelled out.

ETA: Have any of you ever used a hardness tester to determine how much of a difference this makes?

[Vegas Vince]

Thanks. This is exactly how I needed it spelled out. I thought I missed something with the salt brime. Heaven knows I have missed many things!!


Vince

[JohnH]

Others here know a lot more than I, but it strikes me that with the bullet falling through the water (top to bottom of a 5 or 6 gallon bucket) as opposed to being held stationary in the quench (like peice of steel) is going to prevent the formation of quench stalling air bubbles. Blacksmith buddy of mine moves his steel in arcs in a brine quench (uses a 55 gallon drum) to help keep bubbles from forming. Also there is a hell of a lot of difference between a 1 to 20 pound peice of steel at 1300 dF+ and a 1/2 to 1 ounce chuck of lead at 400 dF or so, perhaps (only 375 dF) Even after dropping 500 bullets into 6 gallons of water, I can't find a temperature difference in the water itself. Too many calories required, too small a source. Sounds like a test someone ought to run, but I'm favoring softer alloy these days.

[wmitty]

I apologize to any mechanical engineers and metallurgists who may be reading this and know a lot more about it than I. Without digging out the Strength of Materials books I put behind me so long ago, I believe the iron/carbon phase diagram shows time of cooling to be critical in the hardening of iron to produce steel, the carbon atoms being trapped in the iron only when it is cooled (quenched) at a very rapid rate. The brine allows more rapid cooling than cold water alone; which allows a harder steel to be produced. I guess our question ( if I understand this thread) is whether quenching in a brine solution would produce harder bullets using WW alloy?
If I'm not understanding the question, would someone straighten me out?

[robertbank]

IMHO Felix has it right. You have to be concerned about "Practical" difference as opposed to theory. Hard is hard and after that is just hard. I water quench my 9MM and .45acp for various reasons. With me the bullet, load and gun have little to do with the accuracy in the final analysis. At some point my shooting ability or lack thereof overcomes my attention to detail in loading. If I can get my 30-06 to shoot 1: groups at 100 yards which it regularily does from a rest then life is good and isn't going to get much better no matter how hard I try. Something about the golden (read rust ) years and lack of athletic ability.

[KCSO]

Now I'm just an old country boy and I don't know squat about the why's I just know that we alwasy had a slack tub filled with brine for quenching file steel for blades. Grampa said to do it that way and I did what worked. As to using brine for bullets I have never heard of that before. When I started casting bullets it was mostly big calibers and soft lead. When I got into other rifles I had a fellow over 70 years old tutor me and he always used plain water. Just for S and G I tried some last night in ice water, brine and regular water and I will hardness check them tonight.

[Old Jim]

The reason for the brine quench is so that the bullet will have some residual salt on the surface. When you shoot that deer so far away that it takes you a half a day to get to him the meat won't spoil because of the salted bullet.

[grumble]

Yeah, but if you shoot a steel gong, won't it rust?

[David R]

Thanks KCSO

[hydraulic]

KCSO: I'm not that old!

[Linstrum]

Hi, guys. The explanations about brine preventing steam bubbles from insulating the boolit, salt helping to lower the temperature of the water, etc. are either right on the mark or are pretty darn close to it here as an answer to the question. The reasons why brine is used for quenching are many. Besides salt lowering the freezing point of water (that’s why you salt the ice to make ice cream or put salt on the sidewalk to melt the ice when freezing outside), salt also raises the boiling point of water above 212° F. That is important because as Felix and some others already mentioned, the steam bubbles push the water away from the metal surface and prevent the coolant liquor from making contact with the metal, which slows down the chilling. Steam does not conduct heat very well compared to liquid water, so it is important to keep the bubbles from forming. Two more things the brine does is it makes the water solution wetter by breaking the surface tension so the water makes more intimate contact with the surface, but more importantly the brine increases the specific heat of the cooling solution. The specific heat is a scientific measure of how much heat it takes to raise or lower the temperature of the water a certain specific amount. Pure water at 68° F has a specific heat of 1. A substance with a specific heat of 1 takes one calorie of energy to change the temperature of 15.4-grains of it 1.8 degrees Fahrenheit. That is the same as changing one gram of it one degree Celsius at about room temperature. Things like engine oil, gasoline, alcohol, diesel fuel, kerosene, brake fluid, propane, etc. all have specific heats a whole bunch less than 1 and consequently will not cool things down very fast or effectively compared to water or brine. For some things, like the high carbon and other high alloy steels, having slowed down cooling is extremely important because if the temperature changed too rapidly the metal part being quenched would shatter while being cooled! Like has already been mentioned, some grades of steel require much more rapid cooling to make them hard. For the range of steel alloys available nowadays, they are categorized into brine hardening, water hardening, oil hardening, and air hardening. Yup, some steel alloys are so sensitive that they only need to cool down in air to quench them so they become full hard, like the “A-1” and “A-2” air hardening drill rod. About chilling boolits in brine, I have no experience one way or another whether the extremely rapid chilling done with brine improves the situation any. A good clue is from shot manufacture where the arsenic-doped lead shot alloy is deliberately chilled in the cushion water at the bottom of the shot tower to obtain maximum hardness. Phosphorous, Antimony, and bismuth are arsenic analogues and because chilling works with arsenic it will work for those, too. If yah got the time, give ‘er a try! Washing soda, also known as sodium carbonate, which is also used in swimming pools for raising the pH (not the same as baking soda but can be made from it by heating), is what was preferred by old-time blacksmiths for their brine when they could get it, otherwise rock salt was used because it was available and cheap. Lye works the best but is way, WAY too dangerous to use without the necessary protective safety equipment, though. You should already be wearing eye protection during casting and that goes double with concentrated brine since it will kill the corneas of your eyes just as quickly as molten lead in your eyes! Work safely and have fun!

[sundog]

Old Jim, you're beginning to sound like carpteman....

Linstrum, sodium carbonate. I have soda ash for the pool. Will that work? Ought to. And how much - what ratio. Thought I would give this a try. Biggest problem I have no tester. sundog

[felix]

Corky, I would not use sodium carbonate (ph raiser) because of the high ph. Not only is it bad for the skin (eyes especially), it will rust the boolit fairly quickly. Use sodium bicarbonate, baking soda, for a quick trial because it is considerably lower in ph. Safer for skin and boolits. ... felix

[brimic]

Not sure what the point is. Even if quenching W/W boolits into brine makes it a little harder, its only going to be by a few BHN at most at the cost of a lot fo salt and extra mess. The range of harness for an alloy of lead is very narrow compared to steel.

[StarMetal]

I agree with Brimic. Sometimes we go too far. You know I read that when the Japanese first started making Samurai swords that they tempered the steel by sticking it through a human being, a prisoner of something. I know they tested the sharpness of the edge by seeing how many prisoners they could slice through. This all was brought to a stop. Anyways how far are we going to go to temper our bullets? Water is quite far enough for me.

Joe

[Cayoot]

WOW Star!!!! That's quite a comparison!!! :!:

[StarMetal]

Cayoot

Yeah, sorry....I think I'll try racoon blood.

Joe

[andrew375]

Total rubbish!

The only important thing in quenching bullets is the speed of the drop in temperature from the liquidus / solidus phase to the totally solid phase. That is from about 620 - 750f to below 600f; these are only rough approximations btw. Final temperature is irrelevant although keeping the bullets too cold will slow down the precipitation hardening process.

[felix]

Perfectly said, Andy! Now, how do we do that? This is what this discussion is really about anyway, isn't? ... felix

[sundog]

Okay, so as long as you are getting good boolits without any tearing or bending, run the pot full on and dump them fast as possible in cold, cold water. That's what I've always done when quenching, and they've always turned out good. No reason to change then, eh? sundog

[carpetman]

Lead(casting alloies) can't be tempered. The heat treating and apparent hardening is not really even understood I don't think. Just because brine,oil,hydraulic fluid,dog pee or some such may do certain things to steel for example,doesn't mean it will to our alloies. Years ago---a whole bunch of years ago when the cops first started using radar,there was a heavily circulated rumor that putting tin foil in your hubcaps would mess up their radar. Know where this came from? Airplanes had some stuff called chaff that was basically strips of tin foil that they dispensed into the air. Enemy radar(it was hoped)would get this return and lock onto it and shoot holes in it instead of the airplane. So putting tin foil in the hubcaps would just be more guarantee that they would get a reading on you. Not too worry. That brine solution has a most useful purpose. If you have sinus problems,allergies etc,there is no better cure than irrigating your sinuses. I had severe problems,all types of medications,Dr appointments,missed work(with Dr excuse)until I started irrigating twice a day. No problems since. If you don't know how to do it--it's simple. Mix HOT water with salt. I prefer non-iodized. Probably about 1/2 teaspoon to cup of water. You'll soon learn the proper amount. Too much salt and it will be chemically hot. From the pharmacy get a nasal squeeze bulb. Use this bulb and squirt the solution up each nostril several times and blow it out. Don't waste the brine on bullets--don't think it will do much. That's my story and I'm sticking to it.

[KCSO]

Being curious I cast and quenched 5 bullets from W/W. 5 in Brine 5 in cold water and 5 in tap water. After 48 hours the bullet all came out so close in hardness i don't think I could tell the difference.
I will continue to quench in regular water.

Carpetman
If you irrigate anything here with salt water it dies, hows your sense of smell?

[carpetman]

kcso---Most of the minnows we buy here in Texas for fish bait are raised on minnow farms in Arkansas. Fresh water minnows. But they ship them here in trucks packed in salt. Who would have thunk it,and they are lively. Can't tell my sense of smell diminished any from irrigating my sinuses.

[cropcirclewalker]

Just because of this string, I sent the missus into town for some pickling salt.

Another $1.12 wasted.

Well, I guess it will still keep my quenching bucket from freezing.

Come summer, I guess I can make some pickles. [smilie=s:

[yammerschooner]

Just because of this string, I sent the missus into town for some pickling salt.

Another $1.12 wasted.

Well, I guess it will still keep my quenching bucket from freezing.

Come summer, I guess I can make some pickles. [smilie=s:


Worst case scenario, that salt will keep the weeds out of an asparagus patch. Thanks for testing KSCO.