Q&A for How to Make a Thermos

The paper towels insulate the thermos which is what allows it to keep things hot or cold.

It depends if your thermos is made correctly and if there are no gaps in your insulation. If your thermos is made properly, then it should keep heat in well.

Because the silver-colored surface reflects escaping heat back into the bottle.

Electrical tape has insulating properties, making it the ideal tape to be used. You could use other, strong tapes (e.g. duct tape), but they wouldn't be as well as electrical tape.

Make sure you're not using an ordinary plastic bottle, otherwise it could melt and pour boiling water onto you. If you plan on putting hot liquids into it, make sure to use heatproof plastic or glass.

Yes. Insulation works both to keep cold things cold, as well as keeping hot things hot.

Wrapping the bottom will help with insulation, but it will make the bottle harder to stand safely. You can address this by making a 'stand' out of crumpled foil so that the bottle remains upright on a surface.

You may want to try using other insulators. Adding a layer or two more of electrical tape may be a good idea, but there may be other factors making your thermos ineffective.

The layers built into the thermos take the heat from the liquid it is holding and reflects it back onto the liquid to keep it warm.

Use it because it is a good conductor. Aluminum foil is used in this to keep heat from escaping by reflecting it back into the bottle.

Yes, because now there is a layer of air in between the two layers of the plastic bottle. The layer of air is a very good insulator and will contribute a lot more to keeping the cold inside your thermos.

Most likely, yes, if you wrap the foil and tape very tightly.

The advanced thermos will insulate drinks better because of its better construction.

Yes, I do believe that this will work with both warm and cold liquids. The foil and tape helps keep the warmth and cold in. I personally used duct tape, but I don't really think the tape matters.

No.

No. While aluminum foil is used on the outside, it wouldn't be the best insulator on the inside compared to plastic or glass, so I wouldn't use the cans in place of bottles.

While you don't absolutely need to use cotton, it is a good insulator to use. If the bottles are sealed correctly with lids and tape, no liquid should spill on the cotton.

No. Copper is a conductor, and in a conductor the electricity flows freely. Insulators (which include pure air, plastic, ceramics, and of course, glass) have the opposite effect. In short, you would be much better off with a glass bottle.

Styrofoam is definitely the right way to go with keeping hot and cold locked in! It's very good for insulation.

Electrical tape is a better insulator than other types of tape.

No, you cannot make a thermos with plastic wrap. It does not provide enough insulation.

Yes, though you might need more napkins than you'd use paper towels, unless the napkins are extra thick.

A paper towel. You use it to mop up spills like grape juice or something. When you're done, you throw it away. You can buy it at most drugstores.

Probably not, but both can function well. The bottles act like a Hydro flask, with a two-layer insulation.

Keep the cap on. You can put tinfoil around it as an extra insulating layer.

Most likely not, because a thermos usually traps heat.

You can use the same steps and just put cold liquid into the thermos. The insulation will keep it cold.

There is no substitute. Talk to your neighbor to see if you can have some.

It is difficult to say. It mainly depends on the temperature of the liquid and the temperature of the thermos' surroundings.

Yes, you could try duct tape. But since duct tape has wider strips, it could be difficult to make it air tight.