Catherine’s Concerned About Sunscreen Efficacy: I’ve heard that when sunscreen/sunblock separates, it`s no longer good. That shaking it up to remix it is basically wasted effort and applying it will do no good at all. Is this true? Can sunscreen go bad?
The Left Brain Concurs:
Sunscreen formulations are very sensitive creatures. Most UV absorbers are oil soluble, which means they have to be carefully emulsified to form stable mixtures with water. If the oil and water in the formula are not properly coupled together, the whole formula can go to hell pretty quickly. Here are 3 warning signs that your sunscreen has gone sour:
1. Weird consistency
The consistency of the product has changed over time and now it’s too thick or too thin to spread properly. The spreadability of sunscreens is crucial to proper application and coverage. If it doesn’t spread right, it won’t work right.
The active ingredient has crystallized out, making the lotion feel gritty. When this happens the product is completely worthless. You can’t fix that by shaking.
The product has separated into two different layers. Also not good. At worst, the active ingredient will partition into the oil phase and shaking it may or may not re-suspend it properly. At best, the water-resistance of the product may be compromised and it will wash off too easily. Either way, it`s really not worth using. Go buy a fresh bottle.
The Beauty Brains Bottom Line:
Given the importance of good UV protection, don’t take chances with a bottle of sunscreen that you think may be bad. Most manufacturers of sunscreen products like Coppertone, Himaya, Ocean Potion, and even Jack Black, should gladly refund your money or offer you a replacement if you have a problem.