The candle is a relatively simple concept that has seen material refinements over the years.
At its simplest, a solid fuel source ( such as wax ) embedded with a wick ( usually of braided cotton ). When the wick is set on fire the fuel is consumed slowly, producing light and some heat. A few candles can be enough to give some worthwhile heat to a very small improvised shelter like a lean-to or a snow cave, or a partition of a room.
There are considerable differences in the quality of candles. If stockpiling candles for an emergency or for off-grid use, first obtain some samples and test to see if they a) burn cleanly, i.e. don't sputter and smoke and b) don't burn down too quickly.
It is not advisable to use scented candles. Even the most pleasant scent will grate after a few days.
To make a simple cheap candle try the following:
- empty tin can
- candle wick
- metal paper clip
- small stick of sorts ( like a straw, chopsticks, or fork )
- small pot or double boiler for melting wax
Cut a measure of wick to be slighly longer than the can is high. Bind the paperclip around one end of the wick to act as a bottom anchor. Deposit the paperclip end in the can centered. The other end of the wick is to be draped across the stick, set across the can to support it. Melt the pot of wax on a very low heat, and slowly pour the liquid wax in the can. Allow wax to set for a few hours. The wax will harden at a different rate from the outside and the center, so use a second pouring of wax hours later to just fill in the slight indent in the middle.
This produces a simple container candle. The the tin can may get hot when burning it for a while. This design is to accept the lowest quality resources, and to provide a template to improve on.
Please remember to treat hot wax with the same safety precautions as cooking oil, and a lit candle with the reverence due to a fire.