When your slow cooker can't keep up with your production anymore or if you specialize in very specific applications like dipping taper candles, you may have to explore what the specialized equipment, either professional or semi-professional, has to offer. This article gives a brief overview of what is available out there.
There is a very extended range of custom-made appliances for the professional candlemaker, from the high volume wax melter all the way to the fully-automated production line. As this site mainly targets the beginning and intermediate candlemaking hobbyist, the chances that you're looking at starting a full-scale factory are rather small, so I will only mention the two options that you may want to consider if your production takes off dramatically: the wax melters and the professional double boilers.
If you want to make a large number of candles in a single batch, it is crucial to have the required quantity of melted wax at your immediate disposal. There's nothing more frustrating than having to wait for another batch of wax to melt and reach the desired temperature, which by the way can take an excruciating amount of time in function of the quantity.
To alleviate this problem, you could invest in an electrical wax melter. This appliance is designed to take up that kind of challenge and is available in a very extended range of capacities: from 20 liters (4.3 Gallon) for the basic wax melter (that could perfectly be replaced by a sterilizer) up to more than 7400 liters (1957 Gallon, which equals about 15000 lb of wax) for the professional models.
Wax melters have many advantages: they are fast, available in pretty much any capacity, guarantee even heating, are energy efficient and offer precise digital control of the temperature. Choose the capacity in function of your needs and keep in mind that a wax melter can be pricey, ranging from a hundred bucks (for the 20 liters basic model) to more than 40.000$ (for the 1957 Gallon model).
To make container candles in large batches, you may want to consider a wax melter equipped with a pump and a filler noozle, which will save you the hassle of having to refill a pouring container every thirty seconds. Of course, that kind of setup comes at a price... For a basic wax melter / pump combo, expect to pay a minimum of 5.000$.
Professional double boilers are used mainly to allow the dipping of candles in waxes of different colors simultaneously, for example when making Cut and Carve candles. They are usually made of a stainless steel block with a heating element, are filled with water and can accomodate a variable number of dipping pots (8 pots for the model featured in the picture above).
Another application for high volume double boilers is the dipping of taper candles.
Professional workplaces are often fitted with huge dipping vats where large carousels are dipped, slowly giving shape to hundreds of taper candles at once, whether at a very large scale, as shown on the photo on the left, or more modest (photo on the right).