Annealing ??Tempilaq won't go clear..Just goes black

[bow shot]

Syncro': No, what I meant was: Once I get the faint orange glow, if I hit the case w/ a tempil stick immediately (w/i 0.5 sec) it would not leave a mark near the "danger zone", and that the stick did not indicate that the 400F point did at all travel closer to the head over time after removing the heat. In fact the 400F area rapidly retreated toward the neck.

It does not fit well with my understanding of thermal dynamics for school, but… that's what I observed anyway. I had the same result experimenting with dipping (the cases) in 850F lead for about 10 seconds. I was trusting (an expensive) submersible thermocouple/meter for the lead temperature, and trusting the tempilstick to show me 400f on the brass… FWIW...

 

[Syncrowave]

... the stick did not indicate that the 400F point did at all travel closer to the head over time after removing the heat. In fact the 400F area rapidly retreated toward the neck.

I know it might be counterrintuitive, but most of the heat actually traveled in the opposite direction, from the higher-temperature neck to the lower-temperature body and head. The mass of brass in the (lower-temperature) body and head thus acted as a "heat sink" ... the energy required to raise their temperature was the heat that came out of the shoulder and neck, thus lowering their temperatures.

The reason the 400°F area seemed to "retreat" toward the neck was because the heat traveling into the body and head of the case lowered the temperature of the shoulder first, then the neck, and finally the case mouth last (since this heat had nowhere to go except into the air, and air is a terrible heat sink compared to brass)... the fact that the mouths of your cases stayed hottest the longest is evidence that the heat in the shoulder and body went somewhere, and it didn't go from cold to hot (i.e., from shoulder to mouth) but in just the opposite direction...this is why welding edges is tricky, because the heat has nowhere to go, and it's easy to blow through when you approach an edge because all the heat "piles up" at the edge and suddenly your puddle of molten steel or aluminum has nowhere to go except backwards...

Anyway all this is just a long way of saying, "Well, the bodies and heads of those cases went up in temperature" ... the question is, "How much did they go up in temperature and for how long?" It's a shame those IR thermometers don't work. It'd be an interesting experiment. In the meantime, I'm not sure I'll abandon the "stand the cases in half an inch of water when you anneal them" method I originally learned...

 

[bow shot]

Amen on the IR thermometer. Having the water for cooling certainly won't hurt!

But there was no increase in temperature toward the head after heat removal. Again, that isn't what I would expect at all, but its what the instrument, such as it is (the tempilstick) told me.

I think that what folks commonly see with the 'laq, is the same thing: once the heat is removed, the migration of heat to the case-end ceases. I might be wrong on that, but I'm pretty dang sure… working on memory here, lol!

 

[Syncrowave]

Thanks, Bow Shot, can't argue with that!