Nice discussion... but a little clarification on the physics is in order if you will permit
Comparing aluminium & titanium mugs of the same dimensions, there are two physical properties to consider - not just their conductivity (as correctly listed above).
The other important factor is the emissivity. Just as conductivity is a measure of how fast heat travels through a material, emissivity is a measure of how fast heat is lost from a material by radiation to the environment.
Titanium has a significantly lower conductivity than aluminium - hence the known effects of hot spots while cooking, and the noticeable difference in the speed at which the mug would feel hot on the outside. But at the peak thermal radiation wavelength associated with boiling water - about 4.5 microns - there is also a big difference in their emissivities. Assuming that the outer surface of the mugs is simple oxidised metal, titanium's emissivity is about double that of aluminium (0.5-0.6 versus 0.2-0.4).
So... the heat will take longer to travel through a Ti mug... (of the same thickness) but will then be lost faster through radiation. At least in theory!
The real question is what mechanism is the main form of heat loss from a mug? Convection & evaporation will be removing heat, but at least while it is still very hot I would expect radiation to be the dominant effect.
In short, there's a lot more to it than first meets the eye (or lips!) so the best test is real life usage. Mine's a cheap steel cookset with a copper base coating and a plastic mug if anyone cares But then I haven't really embraced the SUL ethos wholeheartedly...
Nice discussion... but a little clarification on the physics is in order if you will permit Comparing aluminium & titanium mugs of the same dimensions, there are two physical properties to consider - not just their conductivity (as correctly listed above). The other important factor is the emissivity. Just as conductivity is a measure of how fast heat travels through a material, emissivity is a measure of how fast heat is lost from a material by radiation to the environment. Titanium has a significantly lower conductivity than aluminium - hence the known effects of hot spots while cooking, and the noticeable difference in the speed at which the mug would feel hot on the outside. But at the peak thermal radiation wavelength associated with boiling water - about 4.5 microns - there is also a big difference in their emissivities. Assuming that the outer surface of the mugs is simple oxidised metal, titanium's emissivity is about double that of aluminium (0.5-0.6 versus 0.2-0.4). So... the heat will take longer to travel through a Ti mug... (of the same thickness) but will then be lost faster through radiation. At least in theory! The real question is what mechanism is the main form of heat loss from a mug? Convection & evaporation will be removing heat, but at least while it is still very hot I would expect radiation to be the dominant effect. In short, there's a lot more to it than first meets the eye (or lips!) so the best test is real life usage. Mine's a cheap steel cookset with a copper base coating and a plastic mug if anyone cares But then I haven't really embraced the SUL ethos wholeheartedly...
ooooh, cheers JB, I hadnt looked deeply enough into emissivity ......
I can see the point of a large mug aluminium (or titanium if you have too much money and need to get rid of a wadge ), if you are going to cook and drink/eat from the same vessel. However, this is really quite restrictive and most situations you'd be better off with a metal cooking vessel and a plastic mug -- insulated mugs keep your drink hot for ages and are not bank-breakingly expensive.
Asbestos Lips wrote: If you can't stand the heat.............
Harr, harr. Touche,
Robin Evans wrote: If you are not using a mug for cooking why not get a plastic one for £2 rather than a Titanium one for £26 (prices from Cotswold)?You won't burn your lips on the plastic one and it will keep your tea warmer.
Very good question. Two reasons for me: One - I know it's probably all persycholological etc, but drinking coffee out of a plastic mug just doesn't taste the same to me. Plus I worry about flashbacks to what I must have drunk out of in Nursery School
Mostly though, when I was (a lot) younger than I am now, when dinosaurs ruled the land and when titanium was just an element in the periodic table, I went on a British Schools Exploring Society expedition to Arctic Norway. We all have to have the same standard kit, one item of which was a white enamel mug. That mug, whith a bit of old bicycle tape stuck to it so I could recognise it amongst the others, subsequently accompanied me on literally tens of thousands of miles of travel, from wild camping to package hols. I got very fond of it (cue Asbestos Lips with more aspersions), and it was quite a sad moment whe I realised it was so badly battered, chipped, going a funny colour etc etc that even I had to retire it. That was a few years back, but recently I thought it might be nice to find a modern day replacment, hence my unhealthy interest in Snow Peak mugs currently. I know it's a luxury, the double wall is ridiculously expensive when you can get something serviceable in plastic for a fraction of the price, but it is nice to have a bit of kit you can feel good about, actually use almost anywhere, and not weigh you down like a brick or go out of fashion. And it's probably going to outlive me, too, dammit.
I carry a plastic cup on a mini-krab hooked on my 'sack. I use it to dip 'n' scoop from burns (no pun intended) when i'm walking. Coffee or tea tastes better out my Titan kettle though.
Nothing wrong with a few dents. They add a bit of character IMHO.
Nice explanation of emissivity, John. I noticed my titanium kettle is cool enough to handle very quickly after boiling water but now I know why. So I guess the tiles on the space shuttle must have an enormous emissivity.
I don't remember where I read it, but someone had put one of those silicone wristbands that were everywhere a few years back, round the top of their mug to prevent burnt lips. Seemed like a good idea to me, but not tried it.
I have considered trying to fit some silicone tubing over the handles of my titan kettle so you can handle it even when it is on the stove. Not got round to that yet either...
I've got a very nice double wall plastic mug from TX Maxx with a 'heatsaver' top. The nice thing is that the inner and outer walls unscrew from each other to form a mug and a liquid volume/cups measured jug.
Very handy to measure the amount of water needed to re-hydrate dried meals.
This stupid git here last night still, knowing what I'd said here before just the other day, managed to scald the roof of my mouth with eating freshly cooked hot food from the metal mug I was using!
I have a snow peak 450 single wall mug. I use it straight on the stove. It has one of those livestrong bands on it as previously mentioned, which works a treat to prevent burnt lips. And only adds 6 grammes.
I must admit that if I try to drink liquids that have just boiled, I tend to burn my lips and mouth. But that's from the near-boiling liquid. So I tend not to do this...
If the pot/mug is too hot to hold, I use a j-cloth to insulate it. If it's still too hot to hold, it's probably far too hot to drink...
wise simple words capt.----i cannot beleve this thread has ran so long over something as easy as drinking hot liquid from a cup without ending up in a and e
