Botanical Ingredient Spotlight: Benzoin Resin

One of our favorite natural aromatic ingredients for our Aquarian Bath shampoo bars and soaps is Benzoin resin. Benzoin has been important as an incense and medicinally since ancient times. It a botanical resin from the trees Styrax benzoin (Sumatra) or Styrax tonkinensis (Siam). Styrax trees grow in Thailand, Loas, Cambodia, Vietnam, Sumatra and Java. The dark sap of the tree is harvested starting when the tree is 3 years old and is harvested once a year over the next 7-9 years. Trees produce around 1 pound of resin per year. We are currently using Benzoin resin from Loas. When I list this ingredient in our soaps and shampoo bars on our website, I call it Benzoin Botanical resin so that it is not confused with Benzoin, which is a completely unrelated chemical compound. Benzoin resin has a sweet vanilla like aroma due to its unique composition of benzoic acid, cinnaminic acid, and smaller percentages of vanillin, styrol, styracin, phyenyl-prophyl, cinnamate and benzaldehyde. Cinnaminic acid is also found in shea butter and has a honey-like aroma. Benzaldehyde gives bitter almond it's characteristic almondy aroma. Different researchers have found varying chemistries between these two Styrax species, with some finding no cinnaminic acid in Siam varieties. The difference may be due to innate differences between the species, different extraction methods, different growing conditions, or the time of harvest of the resin.

This is our Lavender Vanilla Shampoo Bar. The dark color is from Benzoin resin.  We also make Lemon Vanilla Aloe Shampoo bars. Despite the sticky nature of Benzoin resin, the ingredient leaves no awkward build up in the hair or on the skin, even with hard water. It may provide a slightly volumizing effect for hair, but we need more customer feedback on that point to say with confidence.

Whenever you see an Aquarian Bath shampoo bar or soap listed with the name "Vanilla," we are using Benzoin resin as a substitute. The reason that we prefer Benzoin resin over Vanilla Oleoresin is because Benzoin resin has other very special properties. For many years Benzoin resin has been used an antioxidant for preserving fats and oils. What this means for soap and shampoo bars is that our "Vanilla" soaps and shampoo bars made with a high concentration of Benzoin resin have an extremely long shelf life. I have never seen one of our Vanilla soaps or shampoo bars become rancid, even those tested for years on the shelf. This makes the Vanilla bars very good candidates for ultra-prepared customers who like to buy in quantity. But why would anyone want to have old bars of soap hanging around? Actually, the soaps that have cured the longest, tend to stay harder and last longer in the shower. This is because more water has evaporated from the bar. Some people like to cure their soaps for a longer period of time after receiving them. You can do that very easily by storing your soaps naked in a dry well ventilated place that does not get too warm. Because of its great antioxidant qualities, we also use Benzoin resin in smaller amounts in many of our other soaps and shampoo bars to help extend the shelf life. We have even started adding a very small amount of Benzoin resin to our unscented Castile soaps to extend their shelf life. Benzoin is one of the top ingredients that I have suggested to soap makers in countries where there is high humidity and no air conditioning available. A testament to its ability to endure, the resin has been identified from a more than 200 year old shipwreck.

Vanilla Chai soaps are scented with Benzoin Resin, Clove bud and Cinnamon essential oils

Benzoin resin also acts as a fixative in natural perfumery. We use it in this capacity in our soaps and shampoos to better anchor lighter and more volatile essential oils. A few examples of these bars are Tea Tree, Key Lime Salt Soap and Root Beer Soap. Styrax tonkinensis is the species used most often in perfumery.  You can also find powdered benzoin listed as an ingredient for potpouri or incense formulas.

Thanks for reading our Benzoin resin ingredient spotlight. Hope you enjoyed it and be sure to check out one of our soaps or shampoo bars made with this ingredient by shopping at Aquarian Bath. Please feel welcome to leave a comment.