What's a reliable temperature indicator to use on brass cases for annealing. My understanding is the neck/shoulder should reach about 750F for proper annealing (I know opinions differ) and the body should not get above 450F to prevent softening associated with safety risks. Tempilstik is supposed to be applied after heating the metal therefore my thinking is it may not be accurate due to quick case cooling, and application of Tempilaq to the case prior to annealing may result in inaccurate readings due to direct exposure to the flame tip while the case is rotating. Therefore, I am thinking about using an infrared temperature gun to quickly measure neck/shoulder and case body temperature while exposed to the flame to set the case exposure time (secs). Any thoughts?
What's a reliable temperature indicator for annealing cases?
- Thread starter Cassidy
- Start date
"Not" having to worry about that is just one of the many reasons I love my AMP machine!
(Sorry ... I couldn't stop myself.)
(Sorry ... I couldn't stop myself.)
rijndael
Silver $$ Contributor
Put it on the inside of the neck.
Ned Ludd
Silver $$ Contributor
I look for a very dull red color in the neck/case mouth in a darkened room. This approach has worked very well for me over the years. It is easy to visualize and represents approximately 800 degrees F +/- about 50 degrees F. Cases annealed using this approach are well-annealed, but are not adversely affected in the casehead/webbing region. I have tried the Tempilaq thing a few times, but it seemed needlessly difficult, messy, and the results can sometimes be hard to interpret.
I too go for a short period where I see a dull red glow in the neck in a darkened room. On my Annealeez setup this takes ~5 seconds for my .308 cases and slightly less for my 6.5 PRC cases.
Though there's a wide range of temperature that'll work just fine (like 700-1,000°F), the key to annealing is consistency. . . . and getting to the so called annealing temperature fast enough so as not heating down the body to where it's being annealed too.
Though there's a wide range of temperature that'll work just fine (like 700-1,000°F), the key to annealing is consistency. . . . and getting to the so called annealing temperature fast enough so as not heating down the body to where it's being annealed too.
RegionRat
Gold $$ Contributor
(ETA: TL;DR - Use the glow point and time.)
The advice above is good, and this is why.
Most metals have a Draper Point, that is the temperature where they emit blackbody radiation.
Metals average about 798 degK (977 degF , or 525 degC). There is a little scatter in the frequency of the light such that visible (dull read glow in a darkened room) light will also emit at that point plus or minus depending on the specific metal.
If you are using a flame process that is very consistent, then the time plot of your brass neck temperature would look like a rapid climb because of the thin wall and would also drop fairly fast when pulled from the flame.
Let's call it close to a gust-function shaped plot with temp on the vertical and time on the horizontal. It climbs pretty fast and comes down pretty fast at first but then decays longer than the climb. (That is what keeps the heat from flowing down into the body and head.)
The point of that is when you are consistent with the heat rate, then you can use the time base and the Draper point for a reliable baseline.
That Glow Point (Draper point) happens to be very nearly the same as the temperature you need for the kinds of time dwell you have in thin cartridge brass to anneal. This is just a coincidence and the phenomenon are not tied. It is a lucky break for us.
Even in industrial brass flame annealing settings, with nearly limitless budgets and access to all sorts of instruments and technology, we use that Draper point and time to control the annealing process on thin brass and cartridge necks. Using that time to the glow point, we could adjust the process up or down with time because we had the heat rate set very consistently and didn't allow it to change.
Of course, we had the benefit of the metallurgical labs to test the HV and strength, but at home you typically don't.
What I have recommended to folks is to be very disciplined in the repeatability of the flame setting and position, then use the time base to adjust. With practice, you should be able to repeat the glow point within one to two tenths of a second, where the base times are on the order of five to seven seconds on small stuff and eight to twelve seconds on the big stuff. Practice till your set-up repeats very well within a tenth or two for each session.
A combination of studying your sizing and seating forces against small changes to the time base will give you the results you need, but only if you are disciplined. Small changes are on the order 0.3 seconds longer or shorter than the glow point.
If you don't have the mindset and skill to get this consistency, you are probably better off skipping it or annealing a different way. YMMV
The advice above is good, and this is why.
Most metals have a Draper Point, that is the temperature where they emit blackbody radiation.
Metals average about 798 degK (977 degF , or 525 degC). There is a little scatter in the frequency of the light such that visible (dull read glow in a darkened room) light will also emit at that point plus or minus depending on the specific metal.
If you are using a flame process that is very consistent, then the time plot of your brass neck temperature would look like a rapid climb because of the thin wall and would also drop fairly fast when pulled from the flame.
Let's call it close to a gust-function shaped plot with temp on the vertical and time on the horizontal. It climbs pretty fast and comes down pretty fast at first but then decays longer than the climb. (That is what keeps the heat from flowing down into the body and head.)
The point of that is when you are consistent with the heat rate, then you can use the time base and the Draper point for a reliable baseline.
That Glow Point (Draper point) happens to be very nearly the same as the temperature you need for the kinds of time dwell you have in thin cartridge brass to anneal. This is just a coincidence and the phenomenon are not tied. It is a lucky break for us.
Even in industrial brass flame annealing settings, with nearly limitless budgets and access to all sorts of instruments and technology, we use that Draper point and time to control the annealing process on thin brass and cartridge necks. Using that time to the glow point, we could adjust the process up or down with time because we had the heat rate set very consistently and didn't allow it to change.
Of course, we had the benefit of the metallurgical labs to test the HV and strength, but at home you typically don't.
What I have recommended to folks is to be very disciplined in the repeatability of the flame setting and position, then use the time base to adjust. With practice, you should be able to repeat the glow point within one to two tenths of a second, where the base times are on the order of five to seven seconds on small stuff and eight to twelve seconds on the big stuff. Practice till your set-up repeats very well within a tenth or two for each session.
A combination of studying your sizing and seating forces against small changes to the time base will give you the results you need, but only if you are disciplined. Small changes are on the order 0.3 seconds longer or shorter than the glow point.
If you don't have the mindset and skill to get this consistency, you are probably better off skipping it or annealing a different way. YMMV
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Have a candle and a sponge? 
https://www.thehighroad.org/index.php?threads/different-kind-of-annealing-question.862531/
https://www.thehighroad.org/index.php?threads/different-kind-of-annealing-question.862531/RegionRat
Gold $$ Contributor
The flame of the burner is necessary and makes enough light of its own to see what is going on.
Ned Ludd
Silver $$ Contributor
For me, a darkened room means lights out and shades drawn. However, even at night such a darkened room will usually not even be close to pitch black if there are any outside lights. You just want to be able to see the dull red glow easily, and the torch flame will provide some light. A barely visible dull red glow in a fully lit room will likely appear almost bright cherry red in a darkened room and would be too much, hence the darkened room for better sensitivity.
and a fire extinguisher in your lap lol , I crack me up .
At least 750* inside the neck or 450* below the shoulder will stress relive the neck and shoulder . You can go higher inside the neck just make sure you're not melting the 450* below the shoulder before the higher temp inside the neck melts . You'll likely need a hotter flame or two of them at once . The hotter you heat the neck and shoulder the faster it needs to be done to reduce the chance the heat migrates down the case body . Use the tempilaq you can paint on like finger nail polish
Put the 450* below the shoulder low enough to avoid the flame but not to low .
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Lots of great recommendations here.
Bottom line, have a tidy area, grab some practice brass you don't care about, fire up the torch, turn out the light (I anneal at night) and go at it.
Dull red is key. Very dull red. The first hint of color emanating from the brass. Orange and you've gone too long.
In my right hand is the torch.
On my left hand is a cotton glove.
On my phone is a metronome ap. Infinite beats per minute adjustability. Pick a reasonable flame length, pick a BPM on your metronome ap that is around 8 or 9 per minute.
Tune. Adjust. Adjust BPM or flame intensity or both. You'll have it dialed in within 20 cases or so.
Bottom line, have a tidy area, grab some practice brass you don't care about, fire up the torch, turn out the light (I anneal at night) and go at it.
Dull red is key. Very dull red. The first hint of color emanating from the brass. Orange and you've gone too long.
In my right hand is the torch.
On my left hand is a cotton glove.
On my phone is a metronome ap. Infinite beats per minute adjustability. Pick a reasonable flame length, pick a BPM on your metronome ap that is around 8 or 9 per minute.
Tune. Adjust. Adjust BPM or flame intensity or both. You'll have it dialed in within 20 cases or so.
Metal God - when the Tempilaq inside the necks melt, I assume it re-solidifies when cooled or leaves a residue. How do you remove the Tempilaq from the inside of the neck and body once annealing is done so it does not interfere with neck tension or get down in the body of the brass. Do you clean it out?
Terry
Gold $$ Contributor
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