Sunscreen Formulation, Emulsifier Texture & Ingredient Classification

Question

I have several questions regarding formulation and ingredients:

What is the typical texture provided by Glyceryl Stearate Citrate? Is it thick, medium, or liquid? I need this information before ordering.
Regarding chemical sunscreens like Tinosorb S, DHHB, and Ethylhexyl Triazone, how can they be dissolved, particularly using the LipidSoft™ range and PPG-3 Myristyl Ether? What are the dissolution percentages for BEMT (Tinosorb S), DHHB, and Ethylhexyl Triazone with the general LipidSoft™ type, and what other LipidSoft™ types are noted for dissolving sunscreens (LipidSoft™ SPF, LipidSoft™ B, LipidSoft™ DS, LipidSoft™ DA, LipidSoft™ Solve, LipidSoft™ C1215, LipidSoft™ CC)? To achieve high SPF/PA values like SPF50+ PA++++ or PPD16+, is a combination of sunscreens and appropriate solvents needed?
Are the following ingredients considered preservatives according to the FDA for making a "preservative-free" claim: Hydroxyacetophenone, BHT, Sodium Metabisulfite, Disodium EDTA, Protec™ OX, Protec™ UV, Protec™ SQ? If not, what are their functions?
Is DHHB (Diethylamino Hydroxybenzoyl Hexyl Benzoate) currently available for purchase?

Answer 1

Dissolving Chemical Sunscreens with LipidSoft™ and PPG-3 Myristyl Ether

Regarding dissolving chemical sunscreens like Tinosorb S, DHHB, and Ethylhexyl Triazone, particularly within the LipidSoft™ range and using PPG-3 Myristyl Ether:

PPG-3 Myristyl Ether is known for its high dissolving efficiency for oil-soluble ingredients, including sunscreens. It can dissolve Ethylhexyl Triazone up to 13%.
Within the LipidSoft™ range, the general type can dissolve BEMT (Tinosorb S) up to 12%, DHHB up to 23%, and Ethylhexyl Triazone up to 4.4%. Other LipidSoft™ types specifically noted for their ability to dissolve sunscreens include:
- LipidSoft™ SPF
- LipidSoft™ B
- LipidSoft™ DS
- LipidSoft™ DA
- LipidSoft™ Solve (noted for dissolving Avobenzone up to 26%, but specific percentages for Tinosorb S, DHHB, or EHT are not provided)
- LipidSoft™ C1215 (noted for dissolving chemical sunscreens like Avobenzone)
- LipidSoft™ CC (noted for dissolving chemical sunscreens like Avobenzone)

To achieve high SPF/PA values like SPF50+ PA++++ or PPD16+, you will likely need a combination of sunscreens and appropriate solvents at sufficient concentrations. The exact percentages required to reach a specific SPF/PA level depend on the specific formula and would ideally require testing.

Ingredients and Preservative Claims

Regarding the list of ingredients (Hydroxyacetophenone, BHT, Sodium Metabisulfite, Disodium EDTA, Protec™ OX, Protec™ UV, Protec™ SQ) and whether they are considered preservatives:

None of these ingredients are classified as preservatives by the FDA for the purpose of making a "preservative-free" claim in cosmetic products. They serve other functions such as antioxidants (Hydroxyacetophenone, BHT, Sodium Metabisulfite, Protec™ OX, Protec™ SQ) or chelating agents (Disodium EDTA, Protec™ UV).

Glyceryl Stearate Citrate Texture

Glyceryl Stearate Citrate, when used as an emulsifier on its own, tends to result in a relatively liquid texture. To achieve a thicker or more viscous cream consistency, it is necessary to incorporate thickeners or gelling agents, such as Xanthan Gum, into the formulation.

DHHB Availability

DHHB (Diethylamino Hydroxybenzoyl Hexyl Benzoate) is currently out of stock globally and has been temporarily removed from the website. The company is working to restock it but does not have a confirmed timeline yet.