4. Why must tea lights and votives be burned in a container?
There are three general ways that candles burn. A taper, long and slim, melts a wax pool at the top of the candle and consumes the wax before it can run down the column. (Sometimes tapers will smoke or drip, but that is usually if they are affected by a draft or breeze.) A wide pillar should melt a wax pool almost out to the edge of the candle, and as the candle burns the wall should be squeezed in a bit so that it also melts into the wax pool. Tea lights and votives have a larger wick and produce a flame large enough to melt a wax pool larger than the candle itself, so the wax would run over the tabletop if it were not contained. However, if they are burned in a snug-fitting container they can burn away all of the wax before going out.
We have found that putting a few drops of water in the holders before putting in the tea lights makes it easy to remove unburned and leftover wax.