So many factors go into making a candle that burns perfectly and smells strong. Each step in the candle making process is important, but adding the correct amount of fragrance oil (FO) is one little thing that makes a huge difference.
We often get questions about adding fragrance oil to wax—especially in relation to getting a strong scent throw. But because there are countless factors involved in making a candle turn out exactly the way you want, it’s challenging to provide a concrete, one-size-fits-all answer. However, we do have a few helpful guidelines that can point you in the right direction when adding FO to your candles. We hope these pointers help save you time while testing.
Understanding Fragrance Load
Before we get started, it’s important to understand how much fragrance oil you can safely and effectively mix with wax. As a beginner, you might assume that strong smelling candles simply use more fragrance oil. However, this isn’t necessarily the case. In fact, wax can only hold a certain amount of fragrance oil.
The amount of fragrance oil you add to your wax is known as the fragrance load. It is simply the ratio of wax to fragrance oil. The amount of fragrance oil a wax can hold depends on the type of wax you’re using. Generally, most wax blends can hold between 8 to 12% fragrance.
Even if your wax can hold up to a 12% fragrance load, you don’t necessarily need to add this much FO to make your candles smell strong. When testing, you may find that you achieve an optimal scent throw with as little as 6% fragrance load. Generally speaking, it’s a good idea to start with a smaller fragrance load and work your way up until you get the scent throw you’re looking for.
Testing to find the right fragrance load is time consuming, especially if you use numerous different scents for your candles. However, if you make a lot of candles, think about how much money you can save by not using an excessive amount of fragrance oil in each candle you pour!
Adding the Correct Amount of Fragrance
Now that we’ve covered fragrance loads, it’s important to know how to measure fragrance oil properly. The most important thing to keep in mind is that different fragrance oils have different densities. Therefore, the most accurate way to measure is by weight rather than volume. For example, say you want to make a candle with a 10% fragrance load. If you’re using 16 ounces (1 pound) of wax, that means you would use 1.6 ounces of FO (by weight) to achieve a 10% fragrance load. Using a sensitive digital scale is a great way to measure weights accurately.
When working with small quantities, there may not be much difference when you measure by weight versus volume. However, we still recommend measuring by weight for any size project. Plus, if you’re making a product for sale (or even for gifts that you’ll give to other people), using precise measurements is the only way to create a consistent product with the same results each time.
Tip: Liquid products like fragrance oils tend to be sold by volume (in fluid ounces) rather than by weight. Keep this in mind as you measure your oils.
Achieving a Strong Scent Throw
A burning candle is aesthetically pleasing, but most people also light candles to set the mood with a particular scent. Making a strong-smelling candle is the ultimate goal. After all, no one wants to spend money on fragrance oils only to end up with candles you can’t even tell are burning.
Adding a higher ratio of fragrance oil is one way to achieve a stronger scent throw. However, if you’re still not getting your candles to smell strong enough with a 12% fragrance load, you might be wondering what’s going wrong.
One explanation might simply be that the fragrance oil you’re using isn’t designed to smell super strong. Many FOs are intended to have a lighter, more subtle scent, while others are strong enough to fill your whole house with fragrance. Another explanation may be that you’re not getting your wax to the right temperature before you add your oils, which we’ll discuss more in the last section.
Do my candles smell weak because I ignored the flash point?
If your candles don’t smell as strong as you want them to, we want to stress that it has nothing to do with the fragrance oil’s flash point. Many candle makers don’t understand flash points, which means there’s a lot of misinformation out there.
A flash point is the temperature at which the vapor emitted from a liquid within an enclosed vessel may catch fire when exposed to a source of ignition, such as an open flame. Fragrance oil flash points commonly range from below 138° F to over 200° F.
When it comes to fragrance oils, it’s important to understand that “flash point” is used in a legal context. Simply put: liquids with a flash point below 140° F legally cannot be transported by airplane for safety reasons.
Adding fragrance oil to wax that is hotter than the fragrance oil’s flash point will not cause the scent to burn off. At the same time, fragrance oil won’t cause a candle to burst into flames when it’s lit. This is because the fragrance oil is too diluted with wax to ignite. Fragrance oil can, however, pose a fire hazard if you add too much of it to your wax in an effort to make your candles smell stronger.
In order to understand why, it helps to think of wax as a sponge. Just as a sponge can only hold so much water before it starts leaking out, wax can only hold so much FO until it the oil leaks out.
Here’s where flash points become somewhat relevant. When straight, undiluted fragrance oil begins to pool up in a container candle, the vapors from the oil may ignite if the temperature inside the container is greater than the fragrance oil’s flash point. That’s because your candle container is an enclosed vessel, and the fragrance oil held within the melt pool is exposed to the flame of the candle – a source of ignition.
For this reason, you should never add more fragrance oil than your wax can safely hold. Exceeding the recommended fragrance oil-to-wax ratio is never safe even if it’s the only solution you can think of for making your candles smell stronger.
It’s worth noting that a large volume of fragrance oil is normally needed in order for it to ignite at its flash point when exposed to a flame. The amount of fragrance oil that leaches into your melt pool may or may not be large enough to catch on fire. Either way, testing this theory would be unsafe.