We’ve blogged before about nail polishes so we thought you might be interested in this video from Joanne the Science Goddess that shows the differences between quick drying and long lasting nail polishes.

It’s always fun to watch cosmetics catch on fire!

Today’s post is a shout out for anyone looking for a good Valentines Day present for their beauty-obsessed, science-geeky gal pals.

Flowers and candy are always nice on Valentines Day, but, being chemists, the Beauty Brains also like presents that combine two of our favorite hobbies (beauty science and kissing.) Like this “Make Your Own Lip Balm Kit!”

It’s got everything you need to build your own lip lock laboratory of love – including skin-softening emollients, yummy flavors, and other ingredients that we talked about in our post on how lip gloss works.

Have you tried any DIY cosmetic kits? Leave a comment and share with the rest of the Beauty Brains community.

Kelly’s question…I wanted to see if you might have an answer for me about sunscreen and how to apply it. Forever, I have been told that you apply your products first – eye cream, serums, moisturizer and then your sunscreen is the last step before your makeup. Yesterday, on another well respected blog, Dr. Schultz from Derm TV, suggested that your sunscreen should go on first so it is closest to the skin and can be effective. He suggests that you skip serums in the morning, as they aren’t likely to work as intended. He also suggested that you apply products from the thinnest to the heaviest. Protecting my skin from the sun is my primary concern and if I am not using the products correctly or making them ineffective, I want to know the right way!

The Left Brain’s response:

You raise some interesting questions and the truth is this question is one for which science hasn’t determined an answer. Good arguments could be made for both methods of application. Until there is a definitive study, there is no known “right” answer. But take heart, there is not really a “wrong” answer either.  Here is what the Brains conclude (with all due respect to the doctor) about these issues.

Sunscreen savvy

For physical blocking sunscreens (minerals) like Titanium Dioxide or Zinc Oxide, it doesn’t matter. They’ll work just the same whether it’s put on first or last. In this case, we recommend putting it on after your moisturizer just so the sunscreen doesn’t inhibit the penetrating ability of the moisturizer (or other treatment).

Chemical sunscreens (e.g. Oxycinnamate) are a bit different because the raw materials in the formulas can have an impact on the final SPF rating. That means if you use apply it after your moisturizer, you may reduce the SPF efficacy. So, Zinc & Titanium on last, all other sunscreens on first. Of course, you could actually solve the entire problem by using a moisturizer that contains sunscreen.

Serum uncertainty

As for the question about the serums… again, the science hasn’t been done but there is a good rationale for using them at night rather than in the morning. Many of the active ingredients are UV sensitive so they will most likely be less effective if exposed to the sun. Wearing eye products at night prevents this problem.

What’s your face cream routine? Leave a comment and share your thoughts with the rest of the Beauty Brains community.

After our post on the Top 5 Bath Bombs, we had a follow up question about how many bath bombs would it take to make you float in your tub. Since then we’ve had several emails asking how you can make your own bath bombs.  There’s a ton of info on the web, so to save you the trouble of Googling yourself (that sounds dirty, but it’s not) we thought we’d list our favorite sources for Bath Bomb DIY info.

Build your own bath bombs

1. Teach Soap has a nice description of the ingredients and how to mix them but they’re a bit sketchy on details for the molding process.
2. Better Homes and Garden’s version is good, but not great, mainly because it lacks pictures.
3. CSIRO has a nice, simple version for kids that also provides some basic science background.
4. Not Martha is by far the best with an incredible, step by step description and great pictures.
5. Finally, here are some cool Google videos to show you how the process works.

Have you ever tried to make your own bath bombs? What about other cosmetics? Leave a comment and share your DIY daring with the rest of the Beauty Brains community.

Tammy’s request…It seems I have to change my shampoo all the time because my hair gets used to it. Why is this?

The Right Brain Responds:
A lot of people complain that their shampoo “stops working” or that their hair “gets immune” to it and they have to change. Hair care researchers have looked into this question but have never been able to find any solid scientific reason that this should happen. But, as usual, we have a theory:

Shampoo burnout?

Many shampoos contain some level of condtioning agents. Back in the day, unless your shampoo was a “2-in-1″, it was not generally capable of depositing any conditioning ingredients on your hair. But today, that the 2 in 1 (shampoo plus conditioner) technology has found its way into moisturizing shampoos, color care shampoos, and even some volumizing shampoos. You might find ingredients like silicones, cationic guar gum, and conditioning polymers in almost any shampoo today.

So, although you may not realize it, you may be using a shampoo that provides as much, or almost as much, conditioning as a 2 in 1. Let’s say that you use this kind of shampoo for a while. You might feel that your hair gets over conditioned after a while. So, you decide to change shampoos.

Maybe you start to use a clarifying or deep cleansing shampoo. For a while everything is fine – your hair feels nice and clean again. All the ingredients that built up on your hair from the 2 in 1 shampoos get removed. But then, after using that stripping shampoo for a while, your hair starts to feel dry like straw.

So, you feel the need to switch shampoos again. You pick up a “balancing” shampoo that contains some conditioning ingredients. And after using this one for a while you start to feel buildup and the whole cycle starts all over again.

This kind of process could be the cause of “shampoo burnout.” Of course, this is only a theory, but it is a theory that makes sense when you consider how modern shampoo formulations work.

Kerastase concern

The good people at Kerastase have a different theory, however. We quote:

No, it isn’t true that shampoos don’t work after some time, Karen Ong, brand manager for Kerastase and Redken, says. Like skin, hair and scalp conditions change due to internal and external aggressions such as hormonal levels, diet, sleep and pollution, and need different solutions. That`s why it feels like the shampoo doesn’t work anymore because your needs have changed.

We seriously doubt that diet, sleep or pollution significantly impact shampoo performance. But hey, they’re entitled to their theories too. Of course another possibility is that the perception of needing to change shampoo is just psychological.

What do YOU think? Do you have to change shampoos because they burn out? Leave a comment and share your thoughts with the rest of the Beauty Brains community.