There are probably as many container wax formulas as there are candlemakers !
The ideal formula must have several qualities that we will review now. Unless you plan on using a commercial blend, be prepared to spend a lot of time and do a lot of testing before you find the key to YOUR ideal wax formula...
As we already know, because of its chemical composition, paraffin expands when it gets heated and takes on a liquid form and contracts when it cools off and returns to a solid state.
This is definitely a good thing when you're working on pillar candles, for example, or other types of molded candles, because it makes unmolding the candle so much easier.
But in the case of container candles, this expansion / contraction behavior is really an inconvenience because the last thing you want is having the wax pull back from the sides of the container and ending up with a shrunken block of paraffin rattling inside your jar !
In this case, only one thing to do:
To achieve this goal, there's only one solution:
Let us see what our options are:
Regular, drugstore-grade paraffin has an average melting point of 139°F The difference between the melting temperature and room temperature is rather large and will probably trigger a strong contraction of the wax (think of the shrink well that appears when you make a pillar candle).
Candle wax manufacturers offer a large range of waxes with different melting points for all sorts of applications (see for instance the pages about candlemaking waxes on the IGI Wax website) including a range of specially formulated container waxes with a relatively low melting point (usually between 122°F and 131°F)
You see where I'm heading here : a wax with a melting point of 124°F doesn't have to "come such a long way" when it returns to room temperature and will be less likely to develop a shrink well or pull off from the sides of the container.
If you have access to a low melting point paraffin, use it instead of classic paraffin, it will give you a head start.
Logically, the hotter the temperature when you pour, the larger the difference with the room temperature and the stronger the contraction will be.
This golden rule applies to all container wax formulas:
When you watch paraffin cool off in a pouring jug (I know, I have exciting hobbies !), you will notice that when the wax reaches its congealing point (the temperature at which it starts returning to a solid state), a thin skin starts to form at the surface, starting from the sides of the jug.
This is an indication that it won't take long before the wax returns to its solid state. And it is also the best time to pour the wax into the container.
A couple important points, though::
As your experience grows, you will know when the time has come to pour without the help of a thermometer..
The good news is you don't need a particle accelerator or a master degree in molecular chemistry !
However, a teaspoon of chemistry is needed to understand how it all works:
As explained in the article about paraffin waxes, paraffin is made mostly of long-chain saturated hydrocarbons that don't interact with one another. When paraffin is heated, the molecules start vibrating because of the thermal energy, causing an expansion. Following the same principle, when paraffin cools off, this energy is lost and a contraction occurs (picture this: a row of people standing side by side, arms against their bodies, shoulder against shoulder. Hot, they extend their arms horizontally, sideways and push each other away; cold, back to their initial position. This is exactly what happens in your candles).
On the other hand, vegetable oils are acids with a high molecular weight (fatty acids). They have carbon-carbon double-bonds as well as oxygen atoms that allow them to interact with one another thanks to an hydrogen bond. Because of this and in contrast to paraffin, these oils do not expand (or they almost do not) when heated.
Hydrogenated vegetable oils have some of their double-bonds saturated with hydrogen, which creates tristearines, hard and wax-like. To make a long story short, the more it's hydrogenated, the harder the consistency is.
As an example, soybean oil is not hydrogenated and is liquid. Vegetable shortening (Crisco) is partially hydrogenated and is a firmer semi-solid.
Hydrogenated vegetable oil - for example, vegetable shortening - is chemically compatible with paraffin but does not expand when it is heated. So by mixing hydrogenated vegetable oil and paraffin, you get a wax formula that is less likely to expand / contract than regular paraffin wax.
However, if the selected oil is not fully soluble in paraffin wax, the obtained candles run the risk of "bleeding" or "sweating" oil. In this case, you need to add a binding agent like Vybar or, to a lesser extent, stearic acid.
The expansion / contraction behavior is specific to paraffin but there are other waxes than paraffin that do not have this expansion drawback.
Beeswax, for example, has a chemical structure that is TOTALLY different from that of paraffin wax and won't budge when you heat it or when it cools off.
In other words, a wax formula with equal parts of beeswax and paraffin wax will tend to shrink less during the cooling process, especially if my previous piece of advice (a low pouring temperature) is applied.
Another important property of a good container wax blend is its ability to "stick" to the sides of the container. To achieve this goal, always add a small proportion of microcrystalline soft wax, which is a rather tacky wax, to your wax formula.
If you don't feel like making your own container blend from scratch (but hey ! where's the fun?), don't despair : commercial container blends are pretty much the only blends that are (relatively) easy to find in Europe. Looking for some? Take a look at our supplies finder.
Now that we've seen the different properties a good container wax blend should have, it's time we take a look at the formulas.
Please remember that the formulas I give here are nothing more than a starting point for your own experiments! Do not hesitate to try and modify the proportions, test with other additives, mix wax types...
And always write down the exact composition of the formulas you experiment with in your precious notebook. Don't forget to take note of the temperatures as well ! It would be a shame if you created the perfect container blend only to find yourself unable to reproduce it because you can't remember what you put in it...
The list that follows is certainly not exhaustive but presents the most popular Container blends available on the market. Please note that availability may vary depending on where you reside; I would recommend you also check our supplies finder
MP = Melt Point
Use these formulas as a jump-start, experiment! Have fun and don't forget to always write down what you're using and in which proportions.