Using OMC Ultra-Pure™ (Octinoxate) at a concentration of 20% would theoretically provide an SPF value of approximately 30 to 40. Generally, 1% of OMC contributes about 1.5 to 2.0 SPF units.

However, there are several critical factors you should consider:

1. Regulatory Limits

In Thailand, Europe, and Australia, the maximum legally permitted concentration for OMC Ultra-Pure™ in cosmetic formulations is 10%. Using it at 20% would exceed the safety standards set by the Thai FDA. In Japan, the limit is 20%, while in the USA, it is only 7.5%.

2. UV Protection Range

OMC is a UVB filter (protecting against sunburn). It does not provide effective protection against UVA (which causes aging and long-term skin damage). To achieve "Broad Spectrum" protection, you should combine it with UVA filters.

3. Stability and Incompatibility

• Do not use with Avobenzone: OMC makes Avobenzone unstable, causing the sunscreen to lose its effectiveness quickly when exposed to sunlight.
• Add Antioxidants: It is highly recommended to add an antioxidant like Vitamin E Acetate (at around 0.1%) to the formula to help stabilize the OMC.

4. Cosmetic Feel

Using a high concentration of OMC (such as 10% or more) can make the final product feel greasy and look very shiny on the skin due to its high refractive index.

Recommendation:
If you need a higher SPF while staying within the legal limit of 10% OMC, it is better to combine it with other sunscreen agents (such as Zinc Oxide or Titanium Dioxide) to increase the SPF and provide UVA protection simultaneously.

You can use the BASF Sunscreen Simulator for a more precise estimation based on your specific formula.