The benefits of soft focus technology are a key part of anti-aging skin care. Soft focus (EU) is the optical blurring of skin wrinkles caused by manipulating the transmission and scattering of light from and into skin.
This technology is useful in anti-aging skin care products (EU) to provide an immediate perception of improved texture and fine line reduction. Skin imperfections are seen because of high contrast. Soft focus particles have the ability to optically reduce the contrast and hide the imperfections of the skin surface. The concept can easily be demonstrated on black textured leather, as seen in the image below, right.
Properties of a good soft focus material:
- An optimum material has a high diffuse transmission (>50% of total transmission): the reflected light is evenly distributed and skin appears even. Imperfections appear less clearly.
- A very high diffuse reflection (>80%) is a sign of shine reduction.
- The diffuser particle needs to have minimal light absorption.
- The diffuser particle needs to have high total transmission to provide a natural appearance.
- Most of the light transmission needs to be diffuse in order to provide an even reflection of light from the skin.
Particle parameters affecting soft focus:
- Refractive index (RI) of the particle.
- Difference between the particle RI and that of the vehicle it is in.
- Solid versus hollow
- Particle morphology
- Dow Corning 9701 (EU) (Dimethicone/Vinyl Dimethicone Crosspolymer, silica- Dow Corning (EU)) has a particle size of 1-10 microns, also absorbs sebum, and has an excellent skin feel.
- EP-9293 Al (Dimethicone/Vinyl Dimethicone Crosspolymer, Alumina- Dow Corning) is a 3-5 micron particle.
- SpectrAl PC 401 (Cabot) is a fumed aluminum oxide that has excellent soft focus effects. It has a particle size of 10-30 microns, RI of 1.77, and high diffuse reflection (87% of total reflected) and diffuse transmission (60% of total transmitted).
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