I believe I just saw another non-annealing Facebook repair reel

[bloke]

It appeared to be a really beat up silver plated trumpet.. They never showed it long enough to be able to tell for certain, but it might have been an old Reynolds missing a large portion of its mouth pipe. There were some easy to remove creases in the flare and some dents in the bell throat. I'm sure I saw something that looked like a butane torch go back and forth across the bell throat once or twice with a little flame.

I don't think the video ever showed a still before nor a still after shot of the trumpet, but I heard some trumpet playing at the end.

1013188057551387

[MiBrassFS]

.

[gocsick]

Just for fun.. here is the back of the envelope calculation of how long it would take with over if those small butane torches to properly anneal cold worked brass.

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Annealing a 1.5 mm Thick 80/20 Brass Sheet (10cm x 10cm) with a Butane Torch — Time Estimate and Heat Conduction Effect

If you're annealing a 10cm × 10cm × 2mm piece of 80/20 brass (cartridge brass) using a handheld butane torch, the time it takes depends on whether you're working with a small isolated patch or a section of a much larger sheet.


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SCENARIO 1: ISOLATED 10×10 cm PATCH

Brass mass: ~170 grams

Annealing temperature: ~500–600°C (dull red glow in low light)

Specific heat capacity: ~0.38 J/g·K

Temperature rise needed: ~475 K (from room temp)


Energy required: Q = mcΔT ≈ 170 g × 0.38 × 475 K ≈ 30–32 kJ

Torch Output: Typical handheld butane torch = ~1.5–2.0 kW

Heat transfer efficiency... open flame in air to metal 15%-25%

Effective heating after loss = ~250–400 W (open-air use)

Time Estimate: Time = Energy ÷ Power ≈ 32,000 J ÷ 250–400 W ≈ 80–130 seconds

Realistic heating time (with inefficiency): ~2–3 minutes


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SCENARIO 2: SAME PATCH, BUT PART OF A LARGER SHEET

Brass has high thermal conductivity (~120 W/m·K), so the rest of the sheet acts like a heat sink.

We can estimate how much heat is lost due to conduction into the surrounding metal.

Assumptions:

Brass thermal conductivity (k): 120 W/m·K

Thermal diffusivity (α): ~3.7 × 10⁻⁵ m²/s

Time of heating (t): 180 seconds

Temperature difference (ΔT): 475 K

Effective radial conduction distance: sqrt(α·t) ≈ 0.0815 m


Heat loss by conduction: Q_cond ≈ 2·π·k·ΔT·√(α·t)
Q_cond ≈ 2·π·120·475·0.0815 ≈ ~29,100 J (~29 kJ)

Total energy needed:

Heat to raise patch temp: ~32 kJ

Heat lost into surrounding brass: ~29 kJ

Total: ~61 kJ


Adjusted heating time: Time = 61,000 J ÷ 250–400 W ≈ 150–240 seconds
Realistic time: 6–7 minutes


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SUMMARY

If you’re annealing a 10×10 cm, 1.5mm thick brass patch:

Isolated piece: 2–3 minutes to reach dull red

Part of a large sheet: 5–7 minutes, due to heat loss into surrounding metal


So realistically since an instrument bell isn't an infinite sheet of an isolated patch it will be in between.. about 4 or 5 minutes of continuous heating with one of those small butane torches to do the job.

[bloke]

It's never even occurred to me to try annealing brass with a butane torch. ...just seems too absurd.
Ain't got no time for that.

secure vs insecure:
I'm neither.
I try to not do stupid stuff that doing so decades ago taught me that it was stupid.
I try to plan out ahead of time the best tack for putting something back as close to the way it used to be as possible while doing the least amount of work.
I'm just about as proud of my skills fixing horns as I am proud of being able to paint walls...sigh
As far as putting instruments together is concerned, this is no joy for me. The joy is in having the instrument after I put it together and playing it.
My favorite pastimes are playing music (preferably for money) and taking a break.

The best moment in a repair is when the latches click shut again.

[UncleBeer]

My favorite pastimes are playing music (preferably for money) and taking a break.

This is the way.

[gocsick]

It's never even occurred to me to try annealing brass with a butane torch. ...just seems too absurd.
Ain't got no time for that.

The math also suggests it is pretty absurd.

[the elephant]

The butane micro torches are fine for both annealing and brazing/silver soldering — if the work is confined to a very small area. Most brass tubing in tubas is between 0.3 and 0.5 millimeters thick, so not a problem. It takes time and a lot of freaking butane. I have done both many times with the micro torch when it was more expedient than going out into my carport and setting up my B tank acetylene torch. If I have to silver solder more than a tiny nubbin to a small widget I use the bit gorch with my largest tip — because I ain't no idjit.

I posted a question to one of those Facebook Wonders about annealing, asking why he did not show the brass when it was cherry red and… annealed.

His answer was along the lines of "That would destroy the instrument!"

Okay, then…

[MiBrassFS]

.

[bloke]

I try not to anneal silver plated instruments unless a large percentage of the silver (on the parts that don't require annealing) is gone anyway (as silver plating ends up being consumed with real annealing), but I'm going to pull out the propane and git er dunn.
Again, I don't savor the process; I'm much more of a results person, with the goal being sitting and resting or having enough energy remaining (after I feel like I've done enough money making work) to pick up a tuba and play it for a little while before conking out. In my experience, I can heat up things a lot quicker with propane for a lot less money.

https://tenor.com/xvUK.gif

[gocsick]

Where do you folks see all these entertaining videos? All I see is dog, farm tractor, and jazz related “reels!” No “repair techniques” by “master repair technicians.”

“Missing out on some funny stuff…”

My feed recently became nothing but trains and pretty young ladies cooking complicated recipes wearing insufficient clothing to be safe in a kitchen. I am honestly not sure how that happened .. at least that's what I told my wife when she asked.

[MiBrassFS]

.

[the elephant]

*flick* *flick* *flick* *flick* *flick* *flick*

"Oooooooo, yeah… that molecular matrix is relaxing juuuuust riiiight, baby…"

*flick* *flick* *flick* *flick* *flick* *flick*

What a DB that guy is…

[the elephant]

Tell me you're a dumbass without saying you;re a dumbass.

"Warming the metal somewhat above the ambient room temperature *relaxes* the dents."

[MiBrassFS]

.

[bloke]

Gimme a link…

I just scroll past them and laugh.
I'll start sending them to you.
When you get tired of them, tell me to stop.

[prodigal]

I anneal my high pressure and wildcat rifle brass, but a tuba?!

It should be under less than 85k psi, I'd think....

[the elephant]

Why on earth would you anneal ammo brass? It would explode! Annealing makes the metal dead soft, as in you could smush a tuba with your fingertips. Do you mean hardening, like with a torch and then an oil quench?

[gocsick]

The neck gets severely work hardening and can crack on resizing. So typically every 3 reloads or so the neck region needs to be annealed. You only want to soften the neck though. There is a temperature sensitive paint,, Tempilaq, that you can put on the cartridge.. ideally you want the paint on the neck to melt but to remain of the main body. If the body gets to soft it can fail.. you need the body and case to remain hard.

Now that is a textbook answer... I don't know exactly how people who regularly do reloading actually do it. My guess is the good ol boys skip the paint and go by feels.

[the elephant]

The neck gets severely work hardening and can crack on resizing. So typically every 3 reloads or so the neck region needs to be annealed. You only want to soften the neck though. There is a temperature sensitive paint,, Tempilaq, that you can put on the cartridge.. ideally you want the paint on the neck to melt but to remain of the main body. If the body gets to soft it can fail.. you need the body and case to remain hard.

Now that is a textbook answer... I don't know exactly how people who regularly do reloading actually do it. My guess is the good ol boys skip the paint and go by feels.

Man I miss my reloading and casting days…

[UncleBeer]

Do you mean hardening, like with a torch and then an oil quench?

It's my understanding (and experience) that this only works with ferrous metals. Non-ferrous has to be work-hardened.