Percentage Load vs Content

As its name suggests, percent is so much per hundred or a specified amount per hundred.  This blog discusses percentages and not ratios.

Traditionally candle makers use percent load. For example if they wanted to add 8% load they would add 8g of oil to 100g of wax (100x8%)

The percentages that you see in CLP and IFRA documents is percent weight / weight ie both the wax and the fragrance oil are measured in units of weight. As bases and fragrance oils have different densities, you need to weigh each 'ingredient'. 50ml of one fragrance oil will be a different weight to 50ml of another oil. Due to the different densities of fragrance oils and variances in  temperature,  you cannot measure your ingredients by volume.

CLP and IFRA do not use percentage load. The maximum amount of fragrance oil allowed in 10% CLP is 10g oil added to 90g wax so in every 100g of finished product there is 10g of oil. People often refer to this calculation as content. 

10% load, the traditional candle makers way, is 10g added to 100g which gives a total of 110g of product. To calculate this as a straight percentage (as per CLP);  10g divided by 110g then multiplied by 100 which gives 9.09% so 10% load is 9.09% w/w as per CLP.

Not all wax can hold as much as 10% fragrance oil without the fragrance oil sweating out at some point. Look at the TDS (technical data sheet) for your wax from your wax supplier. Some wax can hold more than 10% and fragrance oil is rarely restricted on the IFRA document in category 12. If you use more than 10% fragrance oil in your wax melts or candles you do not need to have the SDS or CLP recalculated, simply use the ‘up to’ 25% CLP in non hazardous base that most fragrance oil suppliers provide. With a good fragrance oil you shouldn’t need more than 10% fragrance oil in your wax melts. 10% is often far too much for candles as the oil can block the wick and you get cold throw but no hot throw.