White Precipitate in Hair Growth Spray Formulation

Question

I have formulated a 50ml hair growth spray with the following ingredients:

Slim Coffee 2.5g
Biotin Express 1g
Niacinamide 2g
Rice Vitamin 1g
Melatonin Forte 0.5g
1,2-Hexanediol 1.5g
Oryzanol 0.25g
Ethoxydiglycol 2g
Flora Solve Clear 2g
Protec UV 0.5g
Distilled Water q.s. to 50ml
Disodium EDTA 0.1g

The mixing procedure used was:

Combine ingredients 1, 2, 3, 4, 5, 6, 11, and 12 and blend together as the water phase.
Heat ingredients 7, 8, 9, and 10 until dissolved.
Add the heated oil phase (7, 8, 9, 10) to the water phase (1, 2, 3, 4, 5, 6, 11, 12) and blend again until a cloudy white spray is obtained.

After refrigerating the spray overnight, a white precipitate formed at the bottom of the bottle, which is quite difficult to redissolve by shaking.

Could you please advise if I made a mistake in the mixing procedure or used incorrect ingredients/concentrations?

MySkinRecipes Expert · Accepted Answer

Formulation Issue: White Precipitate in Hair Spray

It appears you've created a hair growth spray formulation, but you're encountering a white precipitate after refrigerating the product, which is difficult to redissolve. This suggests that some ingredients are coming out of solution at lower temperatures.

Based on your ingredients and process, the most likely causes for this precipitation are:

High concentration of Protec UV: You are using 0.5g of Protec UV in a 50ml formula, which is approximately 1%. The recommended maximum usage rate for Protec UV (Benzotriazolyl Dodecyl p-Cresol) is 0.1%. Using it at a concentration 10 times higher than recommended is the most probable reason for it precipitating out, especially at cold temperatures, as it is an oil-soluble ingredient.
Solubility of Oryzanol at low temperatures: Pure-Oryzanol™ (gamma Oryzanol) is soluble in the oil phase. While it may dissolve when heated with Ethoxydiglycol and Flora Solve Clear, its solubility in this specific solvent mixture might be limited at refrigeration temperatures, leading to precipitation upon cooling.

Recommendations to fix the issue:

Reduce Protec UV concentration: The most critical step is to significantly reduce the amount of Protec UV in your formula. Use no more than 0.05g in your 50ml batch (0.1% usage rate). This should greatly reduce or eliminate the precipitation caused by this ingredient.
Ensure Oryzanol is fully dissolved: Make sure the Oryzanol is completely dissolved in the heated oil phase (Ethoxydiglycol, Flora Solve Clear, and the reduced amount of Protec UV) before combining it with the water phase. While heating helps, the stability of the solution upon cooling depends on the solvent system's capacity. Pure-Oryzanol™ is best dissolved in oil, and sometimes specific solvents like LipidSoft™ Solve are recommended for better stability.
Review mixing of oil and water phases: Ensure that you are correctly using Flora Solve Clear to solubilize the oil phase into the water phase. Mix Flora Solve Clear with the oil phase ingredients first, then gradually add this mixture to the water phase while stirring or blending until clear.

By reducing the Protec UV to the recommended level, you should see a significant improvement in the stability of your spray at low temperatures. If minor precipitation still occurs, it might be related to the Oryzanol's solubility, and you could explore optimizing the solvent system for the oil phase or slightly reducing the Oryzanol concentration if necessary, while staying within the effective range.