Copper looks good especially those old potstills. A bit of useless information, they use copper to get rid of the sulfides from the ferment and it gives you a better drop of alcohol.
CPU heatsinks with a copper slug work better then just having aluminium to transfer the heat. I like the led to sit on a piece of copper to give it more thermal mass it also adds surface area to transfer the heat into the aluminium body. I cut the shelf out of the L6s and and solder the LED to a threaded copper slug this screws in in place of the shelf. Thermal paste on the thread. Only my opinion but the light seems to handle the heat a lot better.
I’m surprised to see so many comments regarding the thermal conductivity of copper but only one mention of emissivity.
Conductivity is important for, well, conducting heat from the source to the outer surfaces of the light. Copper is great as a PCB core material. However, the total power a light body can dissipate to its environment depends on the surface emissivity of the body material, not its conductivity.
Copper’s emissivity is quite poor compared to anodized aluminum. That means that a copper-bodied light needs to have a higher surface temperature than an anodized aluminum light to dissipate the same amount of heat. Stated differently, for a maximum allowable surface temperature, the copper light needs to run at a lower power level than the aluminum light.
Combine the poor thermal performance with the higher cost, much higher weight, and poor corrosion resistance compared with anodized aluminum and copper just doesn’t make sense to me as a flashlight body material.
1 Thank
I don’t think this is correct. Emissivity (radiation) is only one way of heat dissipation. The other way of heat dissipation is conductivity; heat being transferred from copper surface to surrounding air. You need to look at total heat dissipation in order to evaluate which is better.
Copper is germicidal. Some people dislike the metalic smell of their hand after use. Copper does not stay shiny, but is easily repolished. Touching copper, or storing water in copper, produces too low a dosage to be toxic. The health benefits of copper touch surfaces, outweigh the risks. I find copper flashlights larger than AAA too heavy for me to EDC.
Titanium stays shiny. It is is hypoalergenic. (used to anchor dental implants)
Anodised aluminium is a surface coating that wears off, exposing raw aluminium, which is toxic.
You’re correct that radiation only accounts for a portion of the total heat transfer. The remainder is through natural convection (assuming our light is just sitting in the air with no forced air flow).
However, the rate of heat transfer through natural convection does not depend on the conductivity of the surface material. Rather, it depends on fluid properties like density, viscosity, conductivity (of the fluid), etc. And of course the temperature of the surface and the fluid. Natural convection is driven by how effectively the fluid can transfer heat through itself and how well the temperature gradient induces natural flow.
Try playing with this calculator: Maya HTT - Thermal Wizard
You’ll want Convection Calculators - Natural - Horizontal Cylinder
Any spots where anodizing wears off will quickly oxidize. They may look like raw aluminum because the colored coating is missing, but the surface is actually aluminum oxide. Raw aluminum does not last for very long exposed to air.
Correct. However, I used a slightly different definition of conductivity than what is commonly known. If you draw a system boundary around the flashlight, then convection occurs outside the system boundary. The flashlight dissipates heat two ways. One is radiation (emissivity), the other is conduction (conductivity). However, this is not the thermal conductivity of the material (aluminium) itself that you can lookup easily. The molecules of the flashlight’s surface transfers heat to surrounding air molecules by physical contact; this is conduction.
Yes, it’s true that convection actually happens by conduction at the boundary layer, but the rate at which heat is transferred from the light to the surrounding air does not depend on the material’s thermal conductivity.
This is what we’re concerned with in looking at how much heat a light can generate while maintaining a safe surface temperature - the rate of heat transfer to the surrounding environment.
The only body material property that affects that rate is emissivity.
I’m a practical Aluminum guy for the reasons above. If the most negative is the look of a scratch (which happens on all lights) then it’s all win and no negative. Only copper can give it a run and the weight cost is enormous for what little gain in EDC sized lights.
Definitely!
Perhaps this is true, but I will continue to take lights with stainless steel bezels on the trail. They sell them for some reason. And considering how little flashlights weigh, I will take “heavy” lights when bushwacking. I am not interested in testing aluminum bezels with drop tests onto granite, so they might hold up fine. I just do not assume they will. But each to his own, there is no problem with that. Enjoy your own choice of light.
To the OP’s original question.
What is the “Benefit” in Copper/Titanium/brass lights ?
They sell!
Bling IMO.
Most of the pros and cons have already been discussed. I’m glad to see smelly hands come up because that’s a peeve with my brass lights. Here is another thing to consider and I’m hoping someone here knows more than I do. Brass is often made with a little lead. It’s not much but it can be a source of exposure in our lives. I’ve been seeing it discussed more relative to the brass in keys. Unlike the keys that most post people carry, brass flashlights are both a relatively small niche and a much larger potential source of exposure via surface contact.
true
and the machining process concentrates lead on the surface, even thought brass alloy is only 2.5% lead
…
https://vhcb.org/our-programs/healthy-lead-safe-homes/lead-poisioning-prevention/lead-in-keys
“_it was found that minor handling of keys deposited lead on the hands during a normal task such as removing the key from your pocket and unlocking a door. The amount of lead found was compared to California’s Proposition 65 “no significant risk level” of 0.5 micrograms of lead. It was found that handling some keys deposited lead on the hands as much as 80 times the “no significant risk level”. The average of all keys tested was 19 times the “no significant risk level._”
so I avoid brass flashlights, not only because of the Lead, but also because brass is as heavy as copper but conducts heat much worse than Aluminium, which is worse than copper…
Copper is far less toxic to vertebrates than it is to microorganisms. If you’re going to hold a light in your mouth, it may as well be inherently sterile. I made a bathroom faucet out of pure copper partially for this reason.
titanium is light
but does not conduct heat well
and expensive
copper conducts heat
but is heavy and expensive
and the heat conduction, which is good for the LED, can burn your hand faster
wle
Very interesting. There is a key vending machine common in my area (minute key or something) that offers aluminum keys. I might have to revisit that…