@J E Custom, useful video, thanks for posting.
While you say impurities, I'd suspect the flame luminosity change (the orange flame glow) is due to surface oxidation of the zinc in the brass. Since the secondary combustion zone of the flame is impinging on the brass, as the brass heats up, it changes the chemical process of combustion, which can also cause some of the luminosity.
If you were able to adjust the mix of your torches to give you an orange flame (fuel rich), you would oxidize your brass less.
A good article discussing brass annealing can be found at https://bisonballistics.com/articles/the-science-of-cartridge-brass-annealing
I am not in a hurry to produce ammo faster when I reload. While I would love an automated annealer, it has never been important enough to justify the expense.
Annealing isn't hard - just like everything we do in reloading, it requires attention to detail.
If you want to try annealing, here's what has worked for me over the last 10 years. To start annealing your brass, here's what you need:
Still, the above method is knuckle-dragger stuff. The one benchrest competitor I know has much more sophisticated equipment, like an Amp Annealer. If he has inconsistent annealing, he will see it in variations of the force gauge on his inline press.
Here's a color heat chart for reference:
While you say impurities, I'd suspect the flame luminosity change (the orange flame glow) is due to surface oxidation of the zinc in the brass. Since the secondary combustion zone of the flame is impinging on the brass, as the brass heats up, it changes the chemical process of combustion, which can also cause some of the luminosity.
If you were able to adjust the mix of your torches to give you an orange flame (fuel rich), you would oxidize your brass less.
A good article discussing brass annealing can be found at https://bisonballistics.com/articles/the-science-of-cartridge-brass-annealing
I am not in a hurry to produce ammo faster when I reload. While I would love an automated annealer, it has never been important enough to justify the expense.
Annealing isn't hard - just like everything we do in reloading, it requires attention to detail.
If you want to try annealing, here's what has worked for me over the last 10 years. To start annealing your brass, here's what you need:
- cordless drill
- 1/8th or 3/16Ø rod, approximately 6-8" long - preferably stainless, with no coating/paint.
- Propane torch (in good condition).
- Fire extinguisher handy.
- helps to have a bucket of water. You're not quenching the brass, you're just making it easy to handle. Grab a hot piece of brass and you'll know why.
- Set up your work area so you're comfortable. For gosh's sake, no powder anywhere near you. Ensure the propane torch is stable, and in the event you knock it over, nothing around you is going to get ignited. i.e. don't anneal around stacks of paper.
- Chuck up rod. Have your brass and bucket arranged so the motion is fluid. Put brass on rod, anneal, tip rod down so brass falls into bucket, tip rod up to place another piece. All without burning yourself.
- Annealing:
- To get the hang of it, since most reloaders have a culled/reject brass pile, practice on these.
- Do this in low light. The indirect light from a desk lamp, for example. When you are looking at your brass in the flame, you want the flame to be the brightest object in your view, and the background dark.
- A burner flame has multiple parts. There's the bright blue tip, then you can see a light blue corona above that. You want to hold the brass at the tip of the corona. The point of the corona should be hitting the brass at approximately mid shoulder. This results in slower heating but more consistent heat transfer. If you move your brass into the corona area, you can see the corona flow around the brass.
- Why you hold the flame at approximately mid shoulder: the heat flows in both directions. There is a lot less mass at the neck and case mouth, hence it heats up much faster than the body. You'll get the hang of it, but ultimately you want optimal heat distribution from case mouth down to the bottom of the shoulder.
- I anneal my brass to approximately 800°F, where the brass will start to radiate. It doesn't have a color at this point, but the reflectivity of the brass changes where it becomes a black body radiation object, meaning giving off its own light.
- Tip the drill, dropping the brass into the bucket. Repeat....
- If I start to see the brass glow the very dull red, which indicates I've hit ~950°F, This is still good.
Still, the above method is knuckle-dragger stuff. The one benchrest competitor I know has much more sophisticated equipment, like an Amp Annealer. If he has inconsistent annealing, he will see it in variations of the force gauge on his inline press.
Here's a color heat chart for reference:
