Most candlemakers ship their products with care cards or other such informational material that tell customers not to burn candles for more than 4 hours at a time, not to leave candles unattended, etc. Still, stories of cracked (or worse, exploding) jars abound. A chandler’s worst nightmare is hearing from a customer that their candle caused a fire.
Is there any way to protect against that? Proper wicking, of course… but most candles are tested under ideal conditions and following burn recommendations. And sometimes that slightly-larger wick is a bit too much for a vessel, but also throws amazingly and fills the room in an instant.
Less fragile materials (such as tin and concrete) are also popular. These materials have less of a tendency to crack or explode under extreme changes in heat, but they also just don’t have the same look that a glass jar does.
To help candlemakers decide if a vessel is safe or not, I abuse my vessels with over-wicked power burns and check to see how they hold up under intentional stresses beyond what a reasonable candlemaker would do. Here’s my latest power burn in the Marilyn vessel.
Notice how deep the melt pool is (1.5 inches–I measured). The outside of the thick vessel “only” reads 160F even though the inside is over 200F. The thickness of the vessel means that even under extreme burn conditions, this vessel will hold in all that hot wax and flame. Perfect if your customers like to burn their candles way beyond what their care cards say!