Like I said, scour it under running water, before it gets the chance to oxidise (which happens almost instantly). It’ll be a salmon pink. Within seconds of exposure to air, it’ll have already turned that characteristic “copper color”.
It passivates almost instantly, so cutting it on a lathe, scouring it with steel wool, anything in air, and you’ll never see it in all its pink glory.
Take a slab of pc board, a Cu-bottom pan, etc., and try it.
So if something Cu is pickled and immediately coated, it can be a nice pink color.
So when it’s spinning on the lathe and you’re cutting off the oxidized layer and watching the true nature of the metal spin around, you see it immediately, before air gets to it, under the oil, orange.
Maybe tinged by oil, maybe at higher heat, etc., sure, I’ll believe you when you say that’s what you see, but just try what I suggested. Take a rather large flat(ish) piece of Cu, and under running water give it a good scour. It’ll be a bright salmon-pink. I’ve seen this. As soon as you stop scouring, even under water, it’ll start turning orangey. That’s how fast the oxidation is.
“Copper just above its melting point keeps its pink color when enough light (the camera’s flash in this case) outshines the orange incandescence color.”
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Hmm, and
“What you describe as pink is the actual colour of copper. The colour of a clean, solid surface of high-purity copper is typically salmon red. In your case, the appearance may be further affected by the particle size of the precipitate.”
Doesn’t convection have a bigger impact on cooling than radiation? Certainly with a slight breeze it would, but even with still air it must have a pretty big effect. Anyone know the actual number?
Well, as a rough guess, most small lights that are thermally regulated seem to stabilize their output at about 500 lumens, if you tail-stand them. That’s about 5 watts of power, with maybe 50% going OTF in light? If you’re saying 1 - 2 watts of that is radiative, then that leaves only 0.5 - 1.5 watts for convection.
Doesn’t sound like enough. I thought convective cooling would be 3 or 4 times what radiative cooling can do.
It is - at high power, ratio of convection/radiation dissipation depends a lot on input power/flashlight temperature. S2 head has very small surface area,1-2Watts is enough to increase temperature close to 60C over some time.
Other tweaks may also be negotiable, possibly at an extra charge.
I went with a 7135×8 Biscotti driver and an XPL HI U6-3A LED, along with AR glass and a smooth reflector. Basically copying one of the new Desert Tan S2+ configurations.
Was one of the first to order it, but had to cancel because I had not specified led and driver, et cetera.
Apparently this caused the light to re-appear in stock only moments ago. And I (re)ordered the (truly) last one. Sigh…
EDIT: And 15 hours later it is already on it’s way to me :partying_face:
Mine is going to be a custom build with H1-A 3A boost driver and an XHP50 90+CRI G4 35G. Gotta decide if I'm gonna put a 10º or a 5º TIR on it. Up to 1600+ lumens OTF if I'm not mistaken, I could increase driving current a bit but it's going to be gifted to a non-flashaholic lady (a very smart person).
Barkuti, isn’t the H1-A 20mm? I thought the S2+ used a 17mm driver. I think what you are proposing would be an awesome build, so I’m just wondering how you are going to do it. I might be off on the driver dimensions or maybe there’s another H1-A I’m not aware of. I was looking at the one on KD. Thanks.