For example, at Cire Trudon, wax and fragrance are mixed in small batches before the perfumed wax is carefully poured into candle holders. This is less efficient than concocting a big vat of unscented wax, machine-pouring all the candles, then injecting each with a fragrance, as is customary at most candle factories. But the injection method results in an uneven distribution of fragrance throughout the wax, and often leaves the bottom half of the candle completely unscented.
— Read more at Up in flames: how expensive can a candle get? at The Australian Financial Review.