Producing a safe, effective candle

What goes into testing a candle?
 
Candle making isn’t just melting some wax, adding fragrance, throwing some wicks in a jar, and hoping for the best. It actually involves a fair amount of chemistry and a LOT of testing. I think that’s why my science-minded brain loves it so much! We spent about 14 months testing before selling our first candle. I thought it would be fun to share a snapshot of the work that goes into making a great candle that’s safe for consumers.
 
Choosing Materials
The first step in candle making and testing is to choose the materials you’d like to use and stick with them. This includes container, wax type (soy, paraffin, apricot, coconut, beeswax, or a blend of any of these), and wick family (cotton, wood, zinc core, etc.). Settling on materials prior to testing allows for a more focused approach. In our case, we chose soy wax, ceramic containers, and cotton wicks.
 
Wicks
Settling on a wick size will be dependent on the type of wax used and the container size. Many candle suppliers have wonderful wick guides to provide a starting point, however, testing is still necessary. We tested 6 different wick sizes for our containers and settled on 3 sizes that work for us depending on which fragrance we’re using. Some fragrances will require a larger wick to burn, whereas others burn nicely with a smaller wick. We test each fragrance to find the appropriate wick size.
 
Melt Pool
Ideally, the melt pool (portion of the wax that is melted) should reach the edges of the container within 2-3 hours. The melt pool is what makes a candle fragrant. Achieving a proper melt pool involves choosing the correct wick size for the container. There are many styles of wicks to choose from, and each style comes in many sizes. Some wicks perform better with certain waxes, so choosing the right wick type initially is very important. Once we’ve settled on a wick type (in our case, we chose cotton wicks due to their excellent performance in soy wax), testing with various sizes is important to achieve desired results. A wick that’s too large will have a tall, flickering flame, may produce soot, and will cause the candle to melt too quickly. A wick that is too small won’t burn to the edges of the container and may be drowned by the melted wax. When testing our melt pool, we keep notes on burn time and how much of the top layer is melted. Usually at 1 hour, 50-60% is melted. At 2 hours, 90%, and at 3 hours we like to see a 100% melt pool. Ideal melt pool depth is ½” or less.
 
Jar Temperature
Jar temperature is an often-overlooked factor in candle testing. Our goal is for our jars to be warm, but not so hot that the jar can’t be touched while the candle is burning. We check jar temps throughout the burn cycle to ensure they don’t get too hot.
 
Scent Throw
Scent throw is possibly the most important aspect of a candle to consumers. What’s the point of burning a scented candle if it can’t be smelled? Good scent throw is achieved by using an appropriate amount of fragrance oil. For us, that’s anywhere from 8-10% depending on the fragrance. Fragrance oil must also be added to the wax at the correct temperature in order for the wax and fragrance to bind properly. Fragrance that is not fully bound to the wax can cause leaching which will negatively affect candle performance and aesthetics. Wick size is also a factor in scent throw. Wicks that are too small won’t produce a full melt pool or good scent throw, and wicks that are too large could cause the fragrance to burn off and the candle to smell like burnt wax.
 
Burn Time
It’s important to keep track of how long our test candles burn so we can give customers an accurate estimate of how long they can expect their candles to last. We write burn times on the side or lid of our candle jars to keep an accurate tally. Our candles burn from 40-50 hours depending on the length of each burn.
 
Flame Size and Soot
An ideal flame will be small and steady with minimal flickering. This can be achieved by choosing the proper wick size for the container. Although a small amount of soot is usually fine if all other factors are satisfactory, a large amount of soot can indicate improper wick size or improper binding of wax and fragrance oil. Soot should not be coating the inside of the container or collecting on any surfaces above or near the candle. 
 
Power Burn
Once we’ve got all other factors to our liking, the last step in testing is to perform a power burn. This can be anything over the recommended burn time of ~4 hours. We like to power burn our candles for 12-14 hours at a time. Power burns are important to test the resilience of our container and wicks. It also gives us peace of mind that our candles will be safe even if the customer doesn’t follow recommended guidelines. As a busines owner, it’s important to know how your product will perform under less than ideal conditions.
 
We hope this article has given you some insight into the steps it takes to produce a great candle. If you have any questions about our testing process, please contact us!