The water bath technique
One technique you really need to know about is the water bath technique. It will indeed prove very useful (if not essential) in a multitude of projects.
The main reason why you will use a water bath in your candlemaking projects is to speed up the cooling process of the paraffin contained in the mold you dip in the bath.
This technique is mainly used when making Hurricane shells, for two reasons: settle the shell inclusions faster to avoid that they would float to the surface of the wax and speed up the cooling process of the large volume of paraffine needed in a Hurricane shell (something that would take hours at room temperature).
Another advantage of the water bath technique is that, by speeding up the cooling process, it gives a shiny finish to the candle (more about this in the article titled "3 surface techniques"). This explains why Hurricane shells always have that shiny aspect.
What kind of container should you use?
Before you choose a container to act as a water bath, look at your collection of molds and pick the widest and the highest ones (it could be the same mold or two different ones).
The container you will use must:
be high enough (at least 10 centimeters higher than your highest mold).
have a large enough diameter (at least 20 centimeters larger than your widest mold as it must be able to accomodate the mold itself AND allow enough place for your two hands to move comfortably around it).
The first time I made a Hurricane shell using the water bath technique, I used the mold you can see on the picture on top of this page. As you may notice, the bucket is just large enough to let the mold through. Fine, so I fill the mold with 200°F paraffin, tap its sides scrupulously with a spoon to free any air bubble (giving the mold a great opportunity to become burning hot). Then, like a fool, I burn myself trying to lift it up bare handed. Second attempt, I pick it up by its base, that isn't too hot yet, and dip it in the bucket. Except that, at half height and before the mold reaches the water surface, my hands get stuck between the mold and the sides of the bucket and, eventually, the mold itself won't go any further. Logically, my hands are pushed against the hot mold again, burn them for the second time. That's when pain makes me drop the lot... and 5 kilos of hot wax end up in water!
To make a long story short, always use rather a container too large than too small...
How to handle a burning hot mold?
I strongly advice against using kitchen gloves to handle a mold full of hot wax. There is always a minimal amount of paraffin that will end up on the outside of the mold and make it too slippery to be handled with gloves.
A better idea is to make yourself a simple mold handler.
This unsophisticated device can be as simple as two lengths of electric wire (choose it thick enough, at least 5mm) bent and placed under the mold's base (see picture); it will let you easily move a burning hot mold around.
A word about water
Just because it is the purpose of the water bath to speed up the cooling process of hot wax doesn't mean the water in the bath must be ice cold. Actually, it's much better if the water is at room temperature; the latter is more than enough to "suck up" the heat of the mold without risking to crackle the surface or the candle or to ruin the mold and/or its weldings because of a sudden and important change of temperature.
By the way, did you know there's also such a thing as a warm water bath? Specific projects require that the candle would cool off as slowly as possible, like container candles or candles with a mottled surface effect. In this case, it is possible to dip the mold (or container) in a warm water bath and let the mold cool down slowly, together with the water in the bath.
While I'm talking about containers, remember you should never use the (cold) water bath technique when making container candles. Not only must a container candle cool down as slowly as possible to avoid contraction of the wax, but because most containers are made of glass, there's a risk that the thermal shock would make it burst.
How to make sure the mold won't float?
Paraffin floats ontop of water. In other words, your mold full of paraffin won't sink by itself to the bottom of the water bath: you will need some kind of ballast.
When you buy a mold weight from a candlemaking store, you get a long flexible lead cylinder you can wrap around the mold to increase its weight.
Two problems here: if you're not in the United States, it can be tricky to find; secondly, it's lead, people, not exactly the safest thing to have around!
Fortunately, the homemade alternative works just as fine and is much safer as well: just run to the nearest DIY (Do It Yourself) store and buy a 80 cm length of the heaviest chain they carry. At each end, attach a piece of rope, about 30cm long. Wrap the chain around your mold, just above its base, and use the ropes to fasten it in place (see picture). Easy as 1,2,3!
If your mold doesn't really have a base (only metal molds tend to have one), you'll need to find a heavy item and put it on top of the mold so that it won't tip.
How to find the right water level?
The most important variable in the water bath technique is probably the water level in the bucket: too high and water will flow into the mold, too low and a nasty line (called cold line) will be visible on your candle.
The ideal situation, and that's what we're reaching for, is when the water level in the bucket exactly matches (or is a few millimeters higher than) the wax level in the mold.
Obviously, to get there, you need to be sure about two things:
up to which level you're going to fill the mold,
how much water you'll have to pour in the bucket for the water level to match (or slightly surpass) the wax level in the mold.
The first condition is no real problem as it suffices that you decide once and for all that you'll fill your molds up to 1 centimeter from the top and no further (it is recommended, incidentally, not to fill a mold all the way to the top because of the risk of mixing water and wax).
Where the water level is concerned, some preparatory work is indispensable.
First, make sure your bucket is empty. Then, fill your mold to the maximum level you've decided upon in the previous step and put the mold weight in place (very important because the weight will displace some water as well and must be taken into consideration).
Now place the mold in the empty bucket and fill the bucket with water until the water level reaches the water level in the mold (it's a good idea to add 3 to 5 millimeters to be on the safe side).
Now, carefully take the mold out of the bucket. Allow a few seconds for the water to drip back from the mold into the bucket. The level of water in the bucket is the level you'll have to reproduce for that mold with that type of mold weight.
You should now clearly mark that level using a piece of waterproof electrical tape (be sure it won't go off even after it's been submerged in water - see picture) or draw a line with a waterproof, permanent marker.
As you probably have more than one mold, repeat this process with any other mold that might end up in a water bath some day. Do not forget to identify the marks in the bucket so that you can tell which mark belongs to which mold: use different colors of electrical tape or write a letter or number next to each mark.
The water bath technique has many applications, the main being to speed up the cooling process of paraffin