Liquid toner has turned into a gel!

DoreenDoreen Member
edited April 2019 in Formulating
Yesterday I made my exfoliating toner with 2% salicylic acid (pH 3.74).
Later on I checked the toner and to my surprise it has turned into a gel! ?

I change the formula now and then a bit, this time I lowered the amount of pentylene glycol because I also use betaine (trimethylglycine) as solubilizing aid for the SA. I also like to use extracts, which vary from time to time, depending on what I have in stock that can be used in this formulation.

I always use dipotassium glycyrrhizate (0.5%) in this toner and I know this licorice salt can form a gel at a low pH in the presence of inorganic acids.
But I don't use inorganic acids.
Or so I thought?

Could it be that it has reacted with the hibiscus extract (2% Prodhy-Extract Hibiscus (Aqua (and) Propylene Glycol (and) Hibiscus Sabdariffa Flower Extract) that I used this time?
I know hibiscus is quite acidic, but I don't know if it contains inorganic/mineral acids by nature?

The LOI of my toner:
(Aqua, Propanediol, Betaine, Pentylene Glycol, Salicylic Acid, Glycerin, Propylene Glycol (from the extracts), Dipotassium Glycyrrhizate, Sodium Hydroxide, Hibiscus Sabdariffa Flower Extract, Calendula Officinalis Flower Extract, Anthemis Nobilis Flower Extract, Tilia Cordata Flower Extract, Centaurea Cyanus Flower Extract, Chamomilla Recutita (Matricaria) Flower Extract, Hypericum Perforatum Flower Extract, Allantoin, Phenoxyethanol, Ethylhexylglycerin, Dinatrium EDTA.)

pH: 3.74

Contains Euxyl PE 9010: 0.3% (it might not even be necessary, but just to be on the safe side).

Comments

  • Bill_TogeBill_Toge Member, Professional Chemist
    the most likely culprit is the potassium glycyrrhizate/salicylic acid combination: I should think any form of acid would turn it into a gel, not just an inorganic one (the laws of thermodynamics are not picky)
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • DoreenDoreen Member
    edited April 2019
    @Bill_Toge
    The strange thing is that I always use dipotassium glycyrrhizate in this toner, with 2% salicylic acid, this is the first time that it has happened. It's the first time that I use hibiscus extract though (the other extracts that are mentioned in the LOI come from Prodhyactif Softening, what I've used several times before in this toner). I've been making it for around 2 years now like this without problems. Weird, right?
    Paula's Choice also has this particular licorice salt in one of her 2% SA toners by the way (pH 3.2!).

    Edit: I checked again today, the pH was still 3.74. I put some high shear on the gel to see what would happen and the appearance became milky, like an emulsion. I put it aside for a while, later I checked again and some of the substances (maybe SA or allantoin, or both) had precipitated and formed a cloudy layer on the rest of the liquid which was clear.
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