Home Cosmetic Science Talk Formulating Fragrance problem in Soap

  • Syl

    July 23, 2022 at 5:25 pm

    In my experience all fragrances fade overtime, some faster than others. One cause of lost of fragrance is oxidation, avoid light exposure, store all soaps and soap noodles in a dark container.
    Rancidity will also affect scent, but when this happens the soap will develop a brown color.
    Some people recommend adding arrow root powder to the fragrance before adding it to the soap, I personally did not notice a significant difference.

    Some fragrances just perform better than others in soaps.

  • ozgirl

    July 26, 2022 at 12:28 am

    You could try a fragrance fixative but it is probably easier to use a different fragrance. Avoid fragrances with lots of easily evaporating top notes.

  • ketchito

    July 26, 2022 at 11:17 am

    @Mohandoifode Does your soap contain a chelating agent and an antioxidant?

  • luttie

    August 2, 2022 at 8:48 pm

    How are you adding the fragrance?
    I can second @Syl : I’ve heard about mixing the fragrance with a powder (starch) to make it stay longer. Also, if I’m not getting it wrong, there are some fragrances that are supposed to support the hot environment of soap better (you can check with your supplier) and I’ve seen some soap formulas using up to 5% of fragrance [1] [2]
    The references I could find are not the most relliable one but I’ve heard this multiple times.

    How much are you heating the noodles (temperature)? For how long (time)? Are you adding the fragrance at top temperature or when it’s almost solid?
    Another point: are you mixing directly the fragrance into the soap? Try using a little CAPB or carrier oil (so it is easier to mix it uniformly).

    Most of ULProspectos formulas use <0.5% of fragrance, but if your fragrance is better you can use less… There’s no way to now, really. If your fragrance is more dilluted you’ll need to use more and that’s it. Just be sure to stay within the safety limits.

    My english is quite *meh* but I hope you can understand.

  • CoaJuniorFormulator

    August 4, 2022 at 8:37 am

    Saponification has a habit of eating through fragrance long after you think it should have finished.  As Syl has mentioned good storage is half the battle, though soap benefits from the ability to ‘breath’ a little - keep it airtight at your peril.

    In the UK we are permitted to add up to 3% fragrance IFRA allowing (It’s a bit more complicated than that but as you are technically re-batching I suppose that would be the cleanest description), maybe some additional fragrance from off the bat would help.  Also watch the flash point of your fragrances - let the soap cool as much as you dare before adding.

    Florals hold better than citrus as a rule in soap - May-Chang and Lemongrass hold best if you do need a citrus and essential oils fade faster than fragrance oils.  

    Adding your fragrance to some clay first generally helps a little- I think because clay will initially absorb the oil but would rather absorb the water in the soap and so naturally releases the fragrance slowly as it picks up water instead. It’s not the miracle worker people hope it will be though. 

    Best of luck!  

  • chemicalmatt

    August 5, 2022 at 2:48 pm

    Triethyl citrate…all day long.

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