Sunscreen Lotions: Chemical and Physical Filters

Sunscreen Lotions

• Sunscreen protects from UV radiation, preventing sunburn, premature aging, and skin cancer
• Sunscreen's chemistry involves active plus supportive compounds that absorb or reflect UV radiation

Active Ingredients in Sunscreen

• Sunscreens contain chemical and physical active ingredients

Chemical (Organic) Filters

• Organic compounds absorb UV radiation and turn it into heat
• Effective against UVA/UVB radiation
• Avobenzone absorbs UVA
• Octinoxate (Ethylhexyl methoxycinnamate) absorbs UVB
• Oxybenzone absorbs both UVA and UVB
• Homosalate absorbs UVB
• Octocrylene absorbs UVB and stabilizes other ingredients
• Tinosorb S and Tinosorb M provide broad-spectrum protection for both UVA and UVB
• These ingredients function by absorbing UV ray energy and converting it to a less harmful form

Physical (Mineral) Filters

• Inorganic compounds scatter or reflect UV radiation
• Zinc Oxide (ZnO) acts as a physical filter
• Titanium Dioxide (TiO₂) acts as a physical filter
• Physical filters create a barrier to prevent UV radiation from reaching the skin
• Broad-spectrum protection is provided against UVA and UVB radiation. Suitable for sensitive skin.

Broad-Spectrum Protection

• Broad-spectrum sunscreens protect against UVA and UVB radiation
• UVA rays (320-400 nm) penetrate deeply, causing aging, long-term skin damage, and increasing skin cancer risk
• UVB rays (280-320 nm) are more intense, causing sunburn and direct DNA damage
• Sunscreens combine chemical and physical filters to protect against wavelengths

SPF (Sun Protection Factor)

• SPF measures sunscreen's effectiveness against UVB radiation, which is responsible for sunburn
• Higher SPF correlates to greater protection levels
• SPF 15 blocks 93% of UVB rays
• SPF 30 blocks 97% of UVB rays
• SPF 50 blocks 98% of UVB rays
• No sunscreen blocks 100% of UV rays, reapplying and other measures is still important

Formulation Ingredients

• Sunscreen lotions include ingredients to improve efficacy, texture, stability, and sensory properties
• Emollients hydrate skin and provide smooth application
• Common Emollients are: glycerin, squalane, and dimethicone
• Stabilizers prevent UV filter degradation from sun exposure, stabilizing chemical ones like avobenzone
• Octocrylene is an example of a stabilizer
• Thickening agents and emulsifiers maintain lotion consistency
• Cetyl alcohol and stearyl alcohol are examples of thickening ingredients
• Preservatives prevent microbial contamination and extend shelf life
• Phenoxyethanol and ethylhexylglycerin are common preservatives

Additional Considerations for Sunscreen

• Water-resistant sunscreens remain effective after water or sweat exposure
• Ensuring its usefulness for outdoor activities like swimming and sports
• pH balanced sunscreens (pH 5-7) align with skin's natural pH, reducing irritation
• Antioxidants neutralize UV radiation-generated free radicals
• Some sunscreens utilize Vitamins C and E, and green tea extract, to reduce oxidative stress

How Sunscreen Works

• Chemical filters absorb UV radiation and convert the energy to heat
• Physical filters reflect or scatter UV radiation, preventing skin penetration

Lipstick Base Components

• Typical lipstick consists of pigments, emollients, waxes, oils, and other additives providing texture, color and stability
• The base includes waxes and oils for structure, texture, and spreadability

Waxes in Lipstick

• Waxes provide structural integrity for lipstick
• It allows it to hold its shape while maintaining smoothness during application
• Beeswax is a natural wax from bees that thickens lipstick for smooth application
• Candelilla wax is a plant-derived wax that hardens lipstick and improves shine
• Carnauba wax is a hard, glossy wax adding a glossy finish
• Microcrystalline wax is a synthetic wax that increases flexibility
• Rice bran wax is a soft wax from rice bran oil that moisturizes and provides a creamy texture

Oils and Emollients in Lipstick

• Oils and emollients make lipstick smooth, spreadable, and hydrating
• Castor oil provides smooth application and enhances emollient properties
• Mineral oil moisturizes to prevent lips from drying out
• Jojoba oil improves texture and moisturizes
• Shea butter softens and hydrates the lips
• Coconut oil is a popular emollient for moisturizing and softening

Butters in Lipstick

• Shea butter and mango butter nourish and moisturize lips, preventing dryness

Lipstick Colorants

• Pigments provide many hues for attractive products
• Iron oxides produce shades of red, brown, and orange
• Titanium dioxide is a white pigment that lightens or modifies color
• Lake dyes are pigments created by absorbing a dye onto a substrate, making them more stable

Dyes in Lipstick

• Dyes provide vibrant and intense colors
• Unlike pigments, dyes are water-soluble
• Carmine (CI 75470) is a natural red pigment from crushed cochineal insects for deep red shades
• Red 6 (CI 15850) is a synthetic red dye
• Yellow 5 (CI 19140) and Yellow 6 (CI 15985) are synthetic dyes for yellow and orange hues

Additional Lipstick Ingredients

• Lipsticks are modified with ingredients to improve texture, stability, and sensory experience
• Emulsifiers are used to blend ingredients and prevent separation
• Lecithin is a natural emulsifier from soybeans or sunflower seeds that bind oils and water
• Polysorbates are synthetic emulsifiers to stabilize the formula
• Preservatives prevent contamination and extend shelf life
• Phenoxyethanol preserves to prevent microbial contamination
• Ethylhexylglycerin preserves, and acts as a skin conditioning agent

Silicones in Lipstick

• Silicones improve the texture, spreadability, and wear time
• They also give a silky finish, prevent smudging, and increase longevity

Fragrances and Flavorants in Lipstick

• Fragrances and flavorants enhance the sensory experience
• Vanillin gives a sweet scent or taste
• Peppermint oil is used for a cooling sensation and pleasant fragrance

Antioxidants in Lipstick

• Antioxidants prevent degradation of oils and fats, preserving texture and color
• Vitamin E (Tocopherol) prevents oxidation of oils and moisturizes
• Ascorbic acid (Vitamin C) stabilizes formulations and provides skin benefits

Lipstick Formulation Considerations

• Color results from the balance and combination of pigments and dyes
• Texture results from the ratio of waxes, oils, and butters
• Finish is influenced by the types and ratios of oils, waxes, and silicones, this can range from a matte, glossy, satin, or cream
• Longevity results from higher amounts of film-forming agents
• Hydration results from emollients such as shea butter or glycerin, to keep the lips soft and moisturized