Annealing cases - blowtorch and induction annealing methods

So I need to anneal a few cases. I did it years ago using the “tip them over into the water” system and it didn’t work too well. I’ll do them differently this time. What I need to know is what colour should I heat the brass to. @sungazer I believe you may be able to help?

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@Oldbloke turning the cases while you heat is really a must. Also aim the flame more at the shoulder the neck will still be the first to heat up. You are looking for just a colour change. When you start to see it turn pink you are there give or take a turn. It can change pretty fast from that initial change to pink to a orange which is too far then a red and it is going to give you trouble.

Mmm, OK pink. I thought it was blue?

I thought if it went pink (ha-ha) - it’s overheated. With OB on blue/brownish.

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Read this: -
Then read it again, just to be sure you understand the potential dangers of overheating, or the ineffectiveness of insufficient temperature.
There are absolutes involved with the temperature and time.

OK I just found this in an old SSAA article

  1. Watch for colour changes in the brass, while monitoring the state of
    the shine. As soon as the surface shows a light bluish suffusion – without
    losing its shine – remove the brass from the flame. The colour
    change should occur within five to six seconds.
    the light bluish suffusion signifies a temperature in the desirable
    400-500C-range. Loss of shine, however, indicates that grain growth is
    well under way. You do not want that.

Yep… I’ve annealed before. Also, @Oldbloke - water doesn’t really do anything for brass. Just have a tinfoil BBQ tray or something or something ceramic or whatever that won’t melt and drop them in there. They will cool…

I use a drill and a socket head, in case unsure, I can posta YouTube link.

na got it worked out now. thnx anyway

Colour is a very unreliable way of indicating anything when it comes to metal and heat!

Unless of course your eye is calibrated and light conditions are precisely the same each time (ie: not going to happen so it’s unreliable).

Some of your brass might be suitably annealed, some of it not and some of it cooked…

I think you’re overcomplicating it. After you do a few cases you get the feel for it. It’s really not hard or complicated or tricky.

How do you KNOW that you have achieved the correct temperature for the appropriate time.
Annealing is a precise process, the outcome/s of which can not be overstated.

Don’t disagree. How do I know, by eye based on discolouration.

Not sure about brass. But steel temperature is reliability judged by colour. I would have thought (given it is an alloy) temperature could be judged with some reliability.

There is a cost factor here. If I don’t anneal I’ll be throwing them away soon due to splits. If I anneal I should save most of them. The the choice is, save most or toss them all out! No brained to me.

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Especially as it is the change from the original colour to something else. Wether it be pink or blue :laughing: it that first sign of changing that indicates when it is done.

Only under specific conditions, OB. Colour perception is extremely variable according to light conditions. Steel temps can be guessed at but colour is not a good way to judge when temps are critical to outcomes, such as heat treating. You can get a result but it is not likely to be optimal nor reliably repeatable.

True, it’s not 100% but should be close enough. If it’s not, then I lose a few extra. So what.

There’s probably only one way to say this, with any civility.
There are three possible outcomes to this exacting process, if measured by you eyechrometer.

  1. you have not achieved the appropriate temperature for the required time, in which case you have wasted your time. It’s not a matter of “under annealing”. There’s no such thing. You achieved zip/nada/zero.
  2. you got it right (sometimes) but you have got no real idea how it happened because you have not measured the actual temperature. How repeatable is that result?
  3. you exceeded the destructive temperature (you still have no idea of what temperature you achieved) and the case is actually unsafe for further use. But you wont know that until such time as there is a catastrophic failure.
    Good luck with your guesswork.
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@oldAG I know nothing about annealing cases but i want to do it to the cases i’m making here
Making 12ga (almost) from hell brass
before I fireform them.
Can you talk me / us through how to do it properly?
I have been following this thread and I have watched a couple of (probably dodgy) YouTube vids but as these cases cost me a bit in both time and money I’d like to do it right.
You don’t need to do it right this second but since you seem to know whats what i’d love to get your take on it.

@oldAG so are you saying its a waste of time?

I am NOT saying it is a waste of time. Done properly it is very beneficial.
To do it properly, you have to understand how the grain structure of the brass is changed.
I used to have a two burner automated annealing machine, which still required setting up with temperature sensitive paint, the most commonly used one being Tempilaq. Welding supply shops will either have it or source it for you.

I have moved on from that and now use an AMP induction heating annealer. I anneal a LOT of cases.

Rather than me trying to talk/walk you through the process, I suggest you read the excellent article posted quite some time ago in the 6mmBR web site. It is written by Ken Light whose machine is shown in that article and is the type I used to have.

Please understand that it is a very exacting process, which is why I finally moved to the induction type. But, if you use the gas method correctly, your results will be just as good - it just takes longer in the setting up and, gas burners anywhere near a reloading workshop is not a sensible proposition.

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