Ceramic vs Stainless Steel in coffee mugs

Stainless Steel

Most stainless steel travel mugs are double walled, but are NOT vacuum flasks

They usually have a screw on stainless steel base, or just a plain plastic base. Both of these stop thermal air losses, but are in no way as efficient as a true vacuum flask. It can't be anyway, due to the lid having a drinking hole in it

Lids with sliding covers are impossible to clean, and should be avoided. Just a simple double wall stainless steel mug, with a "reduced spill" style plastic lid and silicone gasket will last many years, be cleanable, and provide reasonable heat retention

Double Walled Ceramic

Double walled ceramic mugs are heavy, and while reasonable strong, generally have two fundamental flaws:

• They are very heavy due to having two ceramic layers, even though both layers are quite thin
• Because the layers are thin, most mugs do not have a handle, as they cannot support one without breaking

Their insulation qualities are fine and they can be-reheated in situ. The typical silicone lids they ship with are easy to wash which is a bonus

If you don't mind not having a handle they are fine, but heavy

I don't like drinking from silicone, it feels weird, and the hole is usually too small. Cutting a bigger hole always ends in disaster (maybe a hole punch would do it?). They also break much more easily than a normal ceramic mug if used while travelling

Metal travel mugs nowadays are made like thermos, so they'll keep an (almost) constant temperature, although not all of them have vacuum betweem their walls.

(Source: Wikipedia)

They'll keep the temperature longer if you fill 'em up; having air in a thermo eases the temperature dropping. It's easier drinking a full mug of tea than drinking it full of strong dark coffee, so it will suit you better.

If you enjoy the idea of not having temperature drops, make sure it's designed as an insulated vacuum flask, and not just having double walls. I personally don't like having my drink at an undrinkable 80 C (170 F) 1 hour after having prepared it. In this list of materials, you can see vacuum has the lowest termal conductivity. I don't know which of those materials is ceramic, or if it's not listed there.

Materials for the isolating walls other than stainless steel are also to be considered; glass insulates better, but breaks easylier. Aluminium will be lighter, but you might feel an unpleasant taste (I do).

Tip from Science: There isn't any doubt that vacuum is the best way to go. What could pass less heat from one side to the other than 'nothing' material. Air is good but not nearly as good as a vacuum. However, a true vacuum creates a lot of pressure on the mug walls because of 15lbs/sq inch of air pressing on the walls of the mug with no resistance from the vacuum inside. Vacuum provides no 'structure' so the walls have to be strong, hence the steel. It is highly unlikely you will find a vacuum double-walled mug that is not stainless for the reason above AND it needs to be manufacturable. Of course, anything is possible, even glass vacuum-insulated mugs but they would be too expensive to manufacture and hence not sell, thus are unavailable. SS is the best price/performance choice. If the mug is plastic inside, it is not a vacuum insulated mug by the way. Handles are often glued on in vacuum insulated SS mugs because screws would break the vacuum seal of the outer wall.

I prefer a travel coffee mug that has handles and an easy to clean lid that comes apart. Screw-on lids are a joke. I've had several and have found if you don't get them tight enough, they will leak and if you tighten them too much, they won't seal and will drip too. I had one that was ceramic for over 10 years but it broke one day when I accidentally dropped it onto a concrete floor. The lid popped-in...did not screw in and the lid came apart.

A lot of the above comments are correct. I have a SS double wall vacuum insulated tumbler that i use for hot or cold liquids. The vacuum insulated walls will keep may drink hot or cold all day if the lid is on. I've put coffee in it at 6am and at noon it was still too hot to drink without just sipping. I've left it full of coke with ice in it on my dresser over night and in the morning it was just as good as hours before. Still lots of ice, not watered down, and it doesn't sweat at all. The SS double wall vacuum insulated does, of course, cost more, but the added cost is more than worth it when you use it and see how well it really does perform. That's the only way to go. You'll never want anything else after using one of these quality items.