Annealing: Why not use a non-contact thermometer?

I'll tell you why I don't think it work out real well. Non contact thermometers have their place and work well for a good number of applications. They work based on emissivity of the object being measured.

From our friends at Wikipedia:
The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation and it may include both visible radiation (light) and infrared radiation, which is not visible to human eyes. The thermal radiation from very hot objects (see photograph) is easily visible to the eye. Quantitatively, emissivity is the ratio of the thermal radiation from a surface to the radiation from an ideal black surface at the same temperature as given by the Stefan–Boltzmann law. The ratio varies from 0 to 1. The surface of a black object emits thermal radiation at the rate of approximately 448 watts per square meter at room temperature (25 °C, 298.15 K); real objects with emissivities less than 1.0 emit radiation at correspondingly lower rates.
Click to expand...

There is much more to it but my guess is that the flame itself would interfere with measuring the brass neck temperature. This is why people tend to use Tempilaq or similar.

Being away from home for the holidays I can't give this a try but that is my guess as to why a remote temperature sensor won't work.

If I was home I would give it a shot.

Ron
 
Tricky to get the beam on the brass and avoid the flame and out of the flames you have to be too quick.

Better would be to set a torch up, heat metal as hot as it will get and use it to calibrate the torch indirectly.
 
Yes, to calibrate the torch and timing, is what I meant. Not in the flame, but pulled out when it looks done, then measure. I think it would be better than guessing.
 
Out of the flame, the neck temperature drops fast. Faster than the display on my IR thermometer can update. Makes it hard to get a repeatable reading.
 
Not only that but they don't work well at all on reflective things.

Aim one at freshly skimmed molten lead in a pot and see if you agree with its reading.
 
Depends on the 'Gun',
True IR works pretty good, but you won't find a true IR gun for $20.
FLIR runs about $1,000 when I got mine for a contract job.

I never had any luck with temp guns with gas or hot die annealing.
Way to easy to read flame or die, and the brass cools way too fast for an accurate maximum temp reading.

Heat gun works with electrical annealing when you use tubing for coils, the coils stay cooler than the brass, so the 'Hot Spot' is the brass.
Made things MUCH more simple.
 
The FLIR camera I had at work a decade ago cost $25K. Today I see limited temperature range devices for a hundredth of that. There's one that's an adapter for cell phones for $250, but it's temperature range doesn't go high enough for case annealing.

The IR thermometry issue in principle is, as mentioned before, emissivity. Emissivity ranges from 0 for a perfect mirror to 1.0 for a perfect black body. Most of the non-contact cheap thermometers you get off the shelf are calibrated for something closer to a black body than to a reflector. 0.95 is a common number for fixed units because it matches a lot of painted surfaces at IR wavelengths. The better ones allow you to change the emissivity number. A table of values for different materials is here.
 
I haven't ordered Tempilaq
Yet. I was looking locally
Like a welding supply etc.
Also, not sure if I should
Buy 650 degrees or 700
Or lower ?
The brass I annealed last
Week as a test looked
Good,but some did not get
Hot enough. I had trouble
Sizing the brass down below
1.630. These don't chamber
I'm my 7.62 rifle. They need
To be 1.624 or lower.
I definitely want to learn how
To do this. Get the process
Down.
 
Bump up your burn time a little.
Staying below 750* will keep you out of trouble.
Staying above 650* will get some benifical annealing.
I find best results around 730*.
 
The radius in the mouth of the shoulder contact hole in case comparators tends to make their absolute numbers low. The difference between two cases, however, is accurate, and measuring that difference is their purpose. You can calibrate them with a headspace GO gauge if you want to go get absolute numbers that are accurate. You can also measure some new commercial ammo. It is usually about 1.628"-1.629", though I've had military cartridges that were at the maximum 1.630".

Welding supply houses often have Tempilstik's, which are crayon-like versions of Tempilaq. You have to get the brass warm before the stick will mark them, but otherwise they work about the same. You can also crush them an paint them on with alcohol as a carrier. You see different numbers recommended. 650-750°F. A lot of folks just compromise on 700°F now. The lower number is probably good if you are heating fast enough to overshoot the mark.
 
Non contact thermometer --

Tried it, does not work,
Using a Giraud Annealing machine, machine doing all the work
so my hands were free
Could not get a temp. reading of anything but the flame
and as said above, cases cooled too fast after the flame
was off them
Tried on 223, 308, 3006, 8mm Mauser

Bytesniffer --

Tempilaq I use is --
750 F inside neck, insures you get brass hot enough
450 F outside lower case, to make shure lower case is not over heated

I have been using the liquid ( shake it real good )
I have heard the crayon type sticks are easier
 
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