Black candles are useful for burning away negativity. they are best used on a Saturday, working with Saturn, the lead planet. Saturn works in a non rushed way so he slows things down.
Black candles can also be used in protection rituals. Far from being sinister, their uses are actually quite benign - for most of the time anyway!
The photos show a black candle brining. Oils can be used to dress the candle and other items can be used with the candle also.
If rituals are done outside - ants love to run off with bits of herb, so this is helping the eco system too!