Troubleshooting aerosol stability discolouration separation damage to cans
I have recently moved to a company that manufacture aerosols, which as a cosmetic chemist, is not something I am knowledgeable about at all.
The product in question is a multi surface polish and the formulation before my arrival (current) is:
Fragrance 0.4% Benzalkonium chloride 0.2% Ethanol 10.0% Carnuba Wax 1.0% Sodium Nitrite 0.1% Sodium
0.4% Water 87.9%
Problems - unstable emulsion, visible splitting, sprays white and turns brown within 24 hours (sometimes staining the surface it is sprayed on to, rusting the can and splitting the can across the middle almost like a tide mark (this is seen after 12 months at 20’c).
My proposed new formulation is:
Water 43.95 Sodium Benzoate (Premix 1) 0.4 Water (Premix 1) 1 Sodium Nitrite
0.4 Water (Premix 2) 1 Benzalkonium Chloride 0.2 Carnuba Wax 1 Fragrance (Premix 3) 0.4 Uvinul A Plus
B (Premix 3)
0.4 Ethanol 10 Sorbitan Oleate (S80) 0.75 Water 41.95
My thoughts were - sorbitan oleate would help emulsification, Uvinul would help solubilise fragrance (if fragrance is potentially causing discolouration although it happens across a variety of fragrances). This formulation was a homogenous, white liquid. I gassed it in a can, sprayed and it was orange coming out of the can.
I know the sensible next steps are to formulate and remove one material at a time to see if there are any reactions I am not thinking of.
I wanted to come here to see if anybody had any thoughts/ideas/solutions or something obvious that I am missing. Surfactants are my jam and I feel a little out out of my depth here. Is anybody able to offer some advice please?