Before placing a product on the market, a manufacturer must ensure that their product is safe, so candles must be tested before putting them on sale.
Candles are typically tested by burning in 4-hour cycles. After each cycle, the candles can be weighed and the burn rates calculated. The flame height and aftersmoke should also be recorded. The candles should also be assessed for sooting. A visual test would identify excessive sooting, but sooting behaviour can`t be formally measured by a visual check. Formal soot measurement can be performed using specialised apparatus. Candle Shack provides this service.