Wax ThermometerDon't even think of making the smallest candle if you don't have an adequate wax thermometer!
I emphasize the word adequate because we're talking about a special thermometer here, actually a candy thermometer, like those used to make jam or candy.
A "classic" thermometer won't do: we need one that covers temperature ranges an everyday thermometer won't cover.
Ideally, you should be able to precisely measure temperatures up to the ignition point of paraffin (round 375°F - or 190°C). A candy thermometer, like the one we will use in our candlemaking projects, covers temperatures ranging from 100°F to 350°F (or 38°C to 177°C), which is sufficient because, believe me, you don't want to know what will happen if the temperature of your paraffin goes higher than that!!!
A good, adequate candlemaking thermometer can prove hard to find (I don't know many people who still make their own jam or candy nowadays) but don't give up! You'll find possible sources for such a thermometer in our supplies finder.
the different types of thermometers
Mercury or alcohol thermometers
The thermometer illustrated on the top picture is of the same model than the one I use. This kind of thermometer is ideal because it is mounted on a steel frame (this lets you use it as a "spoon" to mix dye and scent into the paraffin) and comes equipped with a clip to attach it securely to the side of the melting pot.
Another model is available (not illustrated), without steel frame, and looks like a large medical thermometer. I wouldn't recommend buying such a model mainly because it's impossible to attach it to the melting pot, it's made fragile by its very constitution and, to make things worst, the bulb containing mercury (or alcohol) will be in contact with the bottom of the pot (always hotter than the contents) and this could lead to incorrect temperature readings.
The second picture shows such a dial thermometer. This model also has a clip to attach it to your melting pot. A metal spike plunges into the paraffin (or candle gel) and the temperature can be read on the dial.
Today, candlemakers can also use digital thermometers (last picture). Digital thermometers allow for a simple, fast and precise reading of the wax temperature. They may be a little more expensive but their precision and ease of use make them an excellent choice.
Buy only a model that will display the temperature in Celsius (C) as well as Fahrenheit (F) degrees, unless you like endless twisted mental calculations...
A good thermometer can be expensive but if you do the right choice from the start, your purchase will last you for years (if you're a little careful).
Aside from safety considerations, keeping a constant eye on the temperature of your wax will definetly help you repeat a success and/or avoid repetitive failures. For instance, you want to be sure that, when you add fragrance oil to your wax, the temperature of the latter does not exceed the flash point of your fragrance oil (this would literally "burn" the scent, which cannot be the effect you're looking for)...