What's the Meaning of SPF?

It’s not surprising that many people, including estheticians have questions about sun products. “How do I choose the right one? What is an SPF? Is sunscreen safe for my children? Should I use a waterproof sunscreen?”

First, let’s take a look at the meaning of SPF?
The Sun Protection Factor (SPF) displayed on the sunscreen label ranges from 2 to as high as 50 and refers to the product's ability to screen or block out the sun's harmful rays. For example, if you use a sunscreen with an SPF 15, you can be in the sun 15 times longer that you can without sunscreen before burning. - American Melanoma Foundation

Waterproof products are oil-based, and are highly comedogenic! This means that the pores will be clogged, forming blackheads, comedones, and milia. Imagine all the damage this can cause to an acne client! These sunscreen lotions usually contain very high amounts of chemicals, propylene glycol, mineral oil, and parabens – some of the worst ingredients you can apply to your (or your children’s) skin. The best way to go is definitely with a water-based physical block (Titanium Dioxide, Zinc Oxide) and re-apply every 2-3 hours. Remember, we sweat throughout the day, and waterproof sunscreen just blocks all pore secretions, causing breakouts. It’s much better to choose a light, water-based  sunscreen. Always read the ingredients on the back of the container, and don't go overboard with a high SPF - it is better to choose a mid-range (physical block) SPF and re-apply often!