Dark necks on annealed cases

Cole440

Cole440

Private
Minuteman
Mar 24, 2021
88
38
Southern California
#1
The two with bullets in them are from my last batch of cases. The three without bullets are from the current batch.

I haven't seen the darker brown/black color before. I recently switched to a hotter torch, but also changed my annealing time to compensate.

Looks like the heat line on the cases is in about the same spot. I'm not at all worried about the integrity of the brass. I just thought I'd see if this is normal/common?

IMG_3539.jpeg
 
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#7
If I remember correctly the dark color is from it being in the flame a little too long or the neck had lube on it, but you don’t have that blue heat line on the brass. What kind of gas are you using?
 
#8
Regular propane out of a 20lb bottle and a swirl flame style torch

I had wet tumbled these cases with pins, lemishine, and some simple green wash and wax before I annealed them. That might have contributed a little. Or maybe I just got the necks a little too hot.

I'm not worried about the bodies being soft though and the necks sized and are holding tension just fine, so either way I'm going to shoot them and see how it goes!
 
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#9
Cole440 said:
Regular propane out of a 20lb bottle and a swirl flame style torch

I had wet tumbled these cases with pins, lemishine, and some simple green wash and wax before I annealed them. That might have contributed a little. Or maybe I just got the necks a little too hot.

I'm not worried about the bodies being soft though and the necks sized and are holding tension just fine, so either way I'm going to shoot them and see how it goes!
Click to expand...
Since you're annealing after cleaning, I'd say it's residual cleaning solutions that are being burned.

If you're going to wet tumble, I'd suggest you do that after you've annealed; since the annealing process always leaves a somewhat rough oxidation coating of the outside and inside surfaces of the necks which can interfere with consistent seating. I always anneal before cleaning for this reason.
 
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#10
Cole440 said:
The two with bullets in them are from my last batch of cases. The three without bullets are from the current batch.

I haven't seen the darker brown/black color before. I recently switched to a hotter torch, but also changed my annealing time to compensate.

Looks like the heat line on the cases is in about the same spot. I'm not at all worried about the integrity of the brass. I just thought I'd see if this is normal/common?

View attachment 8357963
Click to expand...

Not so fast Kimosabe, by that logic I can crank my oven to 550 and cook my turkey in half the time. My point? You have more intense flame at the neck and shorter time for the heat to get the shoulder to temp.
 
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#11
straightshooter1 said:
Since you're annealing after cleaning, I'd say it's residual cleaning solutions that are being burned.

If you're going to wet tumble, I'd suggest you do that after you've annealed; since the annealing process always leaves a somewhat rough oxidation coating of the outside and inside surfaces of the necks which can interfere with consistent seating. I always anneal before cleaning for this reason.
Click to expand...
Good thoughts! I hadn't really considered that. I could flip flop the cleaning step. I dip my cases in dry lube before mandrel sizing the necks so I'm not super worried about the seating force (that being if they are totally clean that should be ok).
 
#12
Im2bent said:
Not so fast Kimosabe, by that logic I can crank my oven to 550 and cook my turkey in half the time. My point? You have more intense flame at the neck and shorter time for the heat to get the shoulder to temp.
Click to expand...
Excellent comparison. The reason I didn't really suspect that is that the new flame is much broader and washes over the case a lot more than the pencil flame did. But you still make a good point.
 
#13
That black mark is from the wax reside left on the case after cleaning. If you annealed a clean piece of brass with no wax used on brass the heat will turn the necks darker color and have a faint blue line below the shoulder which means you have over annealed the brass some.

Try cleaning the brass with no wax or polish additive and then anneal. The necks turn darker color not pure black and there should be a faint blue line below the shoulder.





Or this video explains more

 
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#14
Dolomite said:
That black mark is from the wax reside left on the case after cleaning. If you annealed a clean piece of brass with no wax used on brass the heat will turn the necks darker color and have a faint blue line below the shoulder which means you have over annealed the brass some.

Try cleaning the brass with no wax or polish additive and then anneal. The necks turn darker color not pure black and there should be a faint blue line below the shoulder.





Or this video explains more

Click to expand...

The necks turn darker color not pure black and there should be a faint blue line below the shoulder.

If you annealed a clean piece of brass with no wax used on brass the heat will turn the necks darker color and have a faint blue line below the shoulder which means you have over annealed the brass some.

So, which is it? Does your Faint blue line theory mean over or under annealed ? :rolleyes:

1719231453328.png
 
#16
Dolomite said:
I don’t have any technical data but I anneal and have both the faint blue line and dark necks.
Click to expand...
Don't worry about the colors as it has nothing to do with annealing of the metal that's taking place. The colors are about the interation of the heat with residues on the brass and the gases in the flame.

Do an experiement of your own by taking a piece of brass and clean it throughly with some steel wool. Then anneal it as you would normally and see what you get.

Here's a single Federal .308 case I picked up at the range the other day, cleaned it with steel wool and subjected it to a little higher heat than I normally use for annealing AND for twice as long:

Over annealed after steel wool.jpg
 
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