In the spiritual world omens are everywhere and there are no such thing as coincidences. You can use signs around you to guide your life and your workings if you only know how to interpret them. 7 day candles have long been used by hoodooists to read a specific working and determine its effectiveness, or warn of any problems or solutions. Just like reading tea leaves, the burnt candles can provide valuable insight.
SOOT
The soot on a candle is one of the most recognizable results of burning a candle. While in the mundane world one might say this was merely soot, in the spiritual we know there is a message to be interpreted in that soot.
Black soot is a sign of negativity and witchcraft.
White soot is another matter all together. This can indicate spiritual communication, purity, and exorcism. It could indicate that the spirits have heard your prayers and removed the negativity from the working. This is especially true in unhexing rituals. Again, look to the amount of soot to tell you if it is completed or not.
FLAME
The flame is by far the most important part of any candle working. The subtle actions of the flame can tell you a lot from the moment you light it, to the moment it goes out. Let start with lighting the flame.
GLASS
The glass retains the story of the working through the soot and preparation but the glass itself can tell you things about the spell.