Cheap, Easy, Uniform Case Annealing

[denton]

This applies to both rifle and handgun brass, so I guess this is the logical place to put it.

Over the years, I've tried the candle method, my wife's gas range, and inductive heating. Until now, nothing I've tried is quick and easy, or worked with both rifle and handgun brass. This system is pretty cheap, does both rifle and handgun brass, and is very fast.

I probably should have worn gloves.... where was my head? But still, have a look:

 

[boom boom]

Neat method and not too expensive either. I also like the uniformity of annealing that it does compared with flame methods.

 

[Varminterror]

We just ran a salt bath annealing thread this spring. Pretty comprehensive overview of the methods, opportunities, and risks.

 

[denton]

We just ran a salt bath annealing thread this spring. Pretty comprehensive overview of the methods, opportunities, and risks.

Thanks for the info. For some reason, I didn't see that thread when it happened. A couple of comments:

The nitrate salts do not leech metal out of the brass.

The Lee melter is thermostatically controlled. It's just not a very good thermostat. After it has been on for a while, it settles down a bit.

Annealing is roughly linear with time and cubic with temperature. Nothing bad happens if you run at 785-850 F. In this range, brass is annealed in 3 seconds or less.

The salts form a passivated layer on the surface of the metal cup.

I tested the annealing by cutting open and flattening a 223 case. I put it in a vise, and flexed it back and forth with pliers. After 75 flexures, the brass broke. I then annealed it for 3 seconds and moved the brass so it stuck out of the vise again, and started flexing it. At first I annealed every 25 flexes, then I switched to 50. After 225 flexes, the brass was still fine.

You do have to keep well clear of the 1022 F point, but running at 785-850 F, you're well away from that.

The salt mix melts at 500 F. With a little luck, you can sometimes quickly dip the side of a case in the salt (plan on tossing it when done) and get a strip of solid salt up the side of the case. You can let that cool, and then dip the mouth of the case in the molten salt, and see how far up the case the salt strip melts. If it's white, that point is under 500 F. If it's clear, it's over that. It's sort of like Tempilac, but free.

It's a lot cheaper to put together your own system. I paid $16 for the lab stand, $3 each for the two clamps, and $35 for the Lee melter. I already had the meter and high temperature thermocouple, but those can be had on eBay for less than the $20 each I cite in the video, and the bimetallic grill thermometers are under $10. The local chem supply place sold me a one pound jar of each of the two component salts for a total of $20.

 

[Laphroaig]

You do have to keep well clear of the 1022 F point

What is the science behind 1022F?

 

[denton]

I haven't been there, but that is apparently the boiling point. If so, you'd get nitrate vapor coming off.

 

[Strat Rider]

Annealing is roughly linear with time and cubic with temperature. Nothing bad happens if you run at 785-850 F. In this range, brass is annealed in 3 seconds or less.
The salts form a passivated layer on the surface of the metal cup.
I tested the annealing by cutting open and flattening a 223 case. I put it in a vise, and flexed it back and forth with pliers. After 75 flexures, the brass broke. I then annealed it for 3 seconds and moved the brass so it stuck out of the vise again, and started flexing it. At first I annealed every 25 flexes, then I switched to 50. After 225 flexes, the brass was still fine.
You do have to keep well clear of the 1022 F point, but running at 785-850 F, you're well away from that.
The salt mix melts at 500 F. With a little luck, you can sometimes quickly dip the side of a case in the salt (plan on tossing it when done) and get a strip of solid salt up the side of the case. You can let that cool, and then dip the mouth of the case in the molten salt, and see how far up the case the salt strip melts. If it's white, that point is under 500 F. If it's clear, it's over that. It's sort of like Tempilac, but free.
It's a lot cheaper to put together your own system. I paid $16 for the lab stand, $3 each for the two clamps, and $35 for the Lee melter. I already had the meter and high temperature thermocouple, but those can be had on eBay for less than the $20 each I cite in the video, and the bimetallic grill thermometers are under $10. The local chem supply place sold me a one pound jar of each of the two component salts for a total of $20.

Maybe someone can clarify for me the purpose of the Sodium Nitrite. (which is much harder to locate)
I see that the melt point of the Potassium Nitrite is 824-F and the boiling point is 999-F.
If using a PID and believing the perfect temp for salt bath annealing to be 900-F (pulled from other videos) - couldn't a person use the straight Potassium Nitrite which is at most Home Depot's as stump remover ?
What am I missing here ? Thanks

 

[denton]

Maybe someone can clarify for me the purpose of the Sodium Nitrite. (which is much harder to locate)
I see that the melt point of the Potassium Nitrite is 824-F and the boiling point is 999-F.
If using a PID and believing the perfect temp for salt bath annealing to be 900-F (pulled from other videos) - couldn't a person use the straight Potassium Nitrite which is at most Home Depot's as stump remover ?
What am I missing here ? Thanks

You certainly can use pure potassium nitrate. Contrary to what I was led to expect, it works just fine.

The purpose of the sodium nitrate is to form a eutectic mixture. The mixture has a wider range of working temperatures than either substance alone. It has one other subtle effect: When potassium nitrate solidifies, it expands. You'll have a lot of trouble getting the cake out of your pot if you ever want to. The eutectic mixture contracts, and just pops right out.

My experience is that there isn't any reason to run the bath above about 800 F. At that temperature, annealing happens in 3 seconds or less. At 900 F, you have a lot less safety margin, and the extra heat doesn't buy you anything.

If you're searching for "nitrite", that's different stuff. You might try this source: https://www.sciencecompany.com/-P16...jPkWxgxgwJeCdWO2bfHtRQIt7VBZX7bgaAoOuEALw_wcB It's also known as Chile Saltpeter. I think I paid $8 for a pound at our local chemical supply store. One of the earlier posts mentioned an Ace Hardware fertilizer that is probably sodium nitrate. You might try that.

Hope that helps. Let us know about your experience.

 

[Strat Rider]

You certainly can use pure potassium nitrate. Contrary to what I was led to expect, it works just fine.

Good info and based on what you stated there, I think the sodium for shrinkage would be the better idea too.
The stuff Ballistic Creations sells uses the sodium nitrite but another video I saw used Nitrates for both of his chemicals.
It is starting to look like you just need to get close enough - LOL.
I am a firm believer in automating everything when possible to eliminate any inconsistencies and making a rig for salt bath will be a bit more difficult than the DIY annealez type machines.
Decisions decisions - LOL.
Thanks for that link also - those are very good prices and thus, no need to use stump remover.

 

[sparkyv]

Am I missing something, denton. Is a sand bath a reasonable approach instead of the nitrate salts bath?

 

[Blue68f100]

You need something that will make 100% contact with the brass surface. Anything that's not a liquid will not give you a good transfer medium.

 

[CANNONMAN]

WOW! Nice guys! Any problem with residual KNO3 when going back to lead? And a little help with the earlier thread of the same topic.

 

[denton]

WOW! Nice guys! Any problem with residual KNO3 when going back to lead? And a little help with the earlier thread of the same topic.

I have separate melters for lead and nitrates. The nitrates do form a protective film on the cup, which keeps it nice looking.

I ordered a Chinese solder pot from eBay, and it does not have enough power to reach and hold 800 F. I may spring for one with a smaller cup, and see if that works better.

Sand might work. I haven't tested it. But I suspect that Blue68f100 has it right.

 

[Strat Rider]

BTW, I found the Sodium NItrate on Amazon - 1 pound for $12.65 & Free Shipping too - and the Potassium Nitrate can be found through Ace Hardware as Hi-Yield Stump remover ($7) or the Spectracide Stump Remover is pure also. Check the SDS sheet on anything else as I found that Bonide stump remover is something completely different.
Amazon Link
Still not sure if I want to go this route, but the price sure is right.