If you ever accidentally spilled water into your melting recipient, you probably know it already : water sinks immediately to the bottom of the pot and just stays there as big bubbles. If you needed a proof that water and paraffin are perfectly incompatible and that paraffin floats on water, there you are !
This characteristic is put to good use by floating candles, a long time favorite that allows for stunning and very romantic displays.
Because of its chemical composition, any slab of paraffin will float on water, but not all of them will do so even elegantly... If you need convincing, try taking a tealight candle out of its cup and placing it on the surface of a water-filled container : it floats, for sure, but one side tends to sink deeper than the other and it doesn't look like much.
The shape of a floating candle is essential for a good floating behavior. Most importantly, the bottom half of the candle that will be in contact with water should have a bulge shape, similar to the bottom of a boat. Ideally, the general shape of the candle (seen from above) should be as symmetrical as possible. It doesn't HAVE to be round though : a flower or star shape is perfectly acceptable, as long as there is some symmetry to it. It could even be oval- or triangular-shaped, that works too.
The picture above shows the classic shape most entry-level floating candles have. That shape offers the best performances but, by all means, do not feel like you have to stick to it; there are stunning floating candles shaped like a lotus flower and they float perfectly well.
Floating candles can be as sophisticated as you want them to be. From the simple, single-color half sphere to the floating rose flower with various shades of color, nothing is impossible. Of course, you should probably start with something simple and progressively raise the level of difficulty as you learn.
But appearances can be deceiving : the lotus candle pictured above is a lot easier to create than would appear at first sight. So do not hesitate to give floating candles a try, they are fun to make and really enjoyable to burn too.