Burn Test Basics! How To Assess Your Candles For Quality & Performance

Choosing the right wick selection and size

Wick choice can make or break your candle. The wick’s size and type shape the flame’s height, the depth and width of the melt pool, and how evenly the candle burns. If the wick is too small, your candle may tunnel, leaving wax clinging to the sides and wasting those precious ingredients. Too large, and you’re likely to get an oversized flame—this can burn the wax too quickly and even cause your container to become dangerously hot.

Trimming matters just as much as the wick itself. Trim the wick to about 5 mm before each burn. Left too long, a wick produces black smoke, “mushrooming” at the tip, and a flickering flame that’s not just unsightly, but also a fire hazard. By diligently testing various wick sizes and styles as part of your burn test, you can find what works best for your chosen wax, scent, and vessel.

Understanding wax type and additives

Different waxes  bring different personalities to your candle. Soy, paraffin, coconut, and beeswax all have unique melting points and ways of holding scent. Soy wax, for example, may need a wider wick to generate an even melt pool, while paraffin tends to pair well with slimmer wicks due to its lower melting point.

Additives can shift burn behaviour, for better or worse. Glitter can clog the wick, creating a weak or sputtering flame. To avoid disappointing results or safety risks, stick to candle-safe additives and skip anything not intended for candle use.

How fragrance and dye impact your burn

Fragrance and colour are where your creativity shines, but they do need a careful hand. Too much  fragrance oil can smother the flame, clog the wick, and produce smoke, while too little means a faint scent. 

The same goes for dyes; heavy-handed use or unsuitable pigments can lead to uneven burning, mushrooming, or instability in the flame.

What's A Power-Burn?

Let the candle burn until all the wax is used up and the wick goes out by itself. You need to do this to test how well the candle vessel handles the heat from the flame - you don't want your jar shattering due to the heat of the candle's final flame! 

This is known as a power-burn and should be conducted in a sink or somewhere that can catch the glass if it cracks. A power-burn is when you push a candle to its absolute limit to test its safety parameters – customers should not be doing this! It’s always advised to leave 1cm of wax remaining once a candle is done.

Evaluating your candle's overall performance

Now, step back and look at your results from all burn cycles as a whole. Did your candle produce a full melt pool at the right time? Was the flame steady and free from soot? Did the container stay cool enough to touch, and was the scent noticeable in the room as you intended?

If you can say yes to all of these, you’ve got a candle that’s up to scratch! If not, use your findings to guide your next round of recipe adjustments. 

Achieving a reliable burn not only makes your candles more enjoyable and safe, but also helps strengthen trust in your own creative work—and in NI Candle Supplies as your go-to source for quality materials.

Burn Testing Made Easy!

We know that staying organised is key when burn testing your candles, so we’ve put together a downloadable burn test sheet just for you. 

This practical worksheet helps you keep track of every detail, from wick type and wax blend to melt pool depth and fragrance strength. 

Use it to simplify your quality checks and make it easy to compare results between batches. Download your copy and keep your candle testing process smooth and consistent!