Any candle will tunnel if it's not been burned properly (well, that is so long as it is a good quality candle). Every candle has a memory, so the next burn is only as good as the last. To ensure it melts all the way to the edges, follow the candle care guide which is popped inside every one of our candle boxes. On this candle care guide, you'll see we advise always burning the candle for a full 4 hours on the first burn and then up to 4 hours every burn, until the wax has melted all the way to the edges. This is known as a "full-melt pool".You'll find that as the candle burns down, it takes less time for the wax to melt to the edges. This is because the heat is retained further down the candle, assisting with the melting.