When you start increasing your production and the need arises to melt a bigger batch of wax than your double boiler can handle, you will probably look at the next level up, the slow cooker (or multi-cooker).
But it's good to know from the start that how you use it will mainly depend on where you reside.
In the United States? You're in luck Anywhere else? It's still possible but with some restrictions...
The big difference between the US's most popular multi-cooker, the Presto Pot, and pretty much every other brand or model haunting the kitchen countertops around the world is that the Presto Pot comes with a very precise temperature control system that makes it very attractive to candlemakers.
For that reason, I have divided this article into two distinct parts, one being more relevant than the other whether you reside in the States or elsewhere. You're of course welcome to read both sections, out of sheer curiosity.
Lucky you! You have easy access to the fantastic Presto Pot, a multi-cooker equipped with a thermostat unit that goes beyond low, medium and high. Available in a 5 quart (37.99$) and a 10 quart (69.99$) model, it will allow you to melt large batches of any wax you wish to work with .
The Presto Pot is so popular with the candlemaking community that it is often altered to add a spigot, extremely practical to easily transfer melted wax to your pouring containers.
Needless to say, doing so will void your warranty to smithereens but the advantage of an integrated spigot is tremendous. Youtube is full of videos explaining in details how you can modify your multi-cooker yourself. But if you feel that goes beyond your current set of skills, you can purchase an already modified Presto Pot from many different places, including etsy, ebay or even specialized websites.
A piece of advice though: some sellers are nothing more than cow-boys who couldn't do a clean weld if their life depended on it. Always check a seller's customer feedback before you proceed to purchase.
As I mentioned earlier in the introduction, we do have slow and multi-cookers in Europe, of course. But unfortunately, they all tend to come with the same fatal flaw: the lack of precision of their thermostat. Most of the models have three temperature settings: low, high and keep warm. You may have medium, if you're lucky. How this translates to degrees, Celsius or Fahrenheit, is one of the world's great mysteries. What we know for sure is that these basic settings do not meet the safety requirements for melting wax.
I can hear what you're thinking: "how about I order a Presto Pot from the United States?" I give you two reasons why that is not a good idea:
This means you would be the proud owner of a 300 EUR plus Presto Pot... For much less than that, you could purchase a semi-professional 27 liters wax melter or even 3 to 4 units of the appliance I am about to introduce you to
Fortunately, there is a very good alternative for the elusive Presto Pot or the unsatisfactory slow cooker: the sterilizer.
A sterilizer like the one pictured above is originally designed to sterilize canning jars but can also be used as a warm drink dispenser (great for coffee, tea, soup, mulled wine) or to keep stew-like dishes warm.
The model above has a maximum capacity of 27 liters and above all a thermostat that allows for precise temperature control in a range between 86°F and 212°F, which makes it a perfect candidate for us candlemakers. Furthermore, it comes equipped with a spigot that makes it extremely easy to transfer any amount of melted wax you want to your pouring pots (on that note, know that when you turn off your sterilizer, the wax left inside will harden and clog the spigot; no big deal, it will be functional again when you turn the appliance back on and enough heat has been generated).
As it comes with a rather attractive price tag (a model similar to the one pictured can be purchased for somewhere between 69 and 100 EUR), it could be a very good investment for the candlemaker looking to gear up his production.
Available from Amazon among others but not everywhere: the electric sterilizer seems to be a european thing.
As the sterilizer mentioned above can be difficult to find depending on where you reside, there is a third alternative that's easier to come by: the soup kettle.
With a capacity of 10 liters (about 10 quarts), its thermostat is not graduated in temperatures but it's precise enough to be used safely once you know what the graduations amount to, temperature wise. It can heat its contents to between 95°F and 203°F and "only" consumes 400W at its highest setting.
So all in all a good alternative if the Presto Pot and the sterilizer are not available to you, even though its capacity is less than half that of a sterilizer (but pretty much the same as the largest Presto Pot). Usually between 50 and 80 EUR (or around 85 USD).
Easy to find, one of the sources being Amazon.