The DIY movement is amazing for many reasons. Making something with your own hands feels good and gives you an appreciation for the craftsmanship involved in making other products. In the best cases, when you create a genius product that all your friends want (we’ve mixed up a few great DIY skin recipes here) it’s a path to financial freedom.But in the worst cases, it’s a path to cystic acne. There are a couple of misguided (though well-meaning) DIY tips being shared on social media sites that, for the sake of our skin, should not follow us into 2014, and here they are:1. Do Not Make Your Own Cleansing OilI had a very enlightening conversation with a dermatologist friend who brought this topic to my attention. She was mortified by the number of patients with deep cystic acne from using DIY Cleansing Oils. Even people with no history of acne have experienced eruptions from this DIY project. I admit that there are many DIYers who swear by homemade cleansing oils and are probably up in arms right now, but this is not a method that works for everyone.DIY cleansing oils don’t clean the skin: Nine out of 10 commercial cleansing oils contain surfactants to help whisk the dirt away during rinsing. DIY cleansing oils don’t. From the chemical perspective, this keeps the oil from cleaning pore-clogging debris off the skin. Here’s why: A surfactant has an oil-loving tail connected to a water-loving head (hydrophilic). The tails of the surfactants are instantly attracted to dirt, dead skin and sebum, surrounding it and creating a “micelle” (picture a beach ball with peach fuzz). The tails form a circle around the dirt, dead skin and sebum, leaving the water-loving heads on the outside. Being true to their hydrophilic nature, the heads connect with the water during rinsing (that’s when the cleansing oil turns white) and are swept away down the drain dragging the tails and pore-clogging materials along with them.DIY cleansing oils cannot simply be rinsed away: As most of us learned in elementary school, oil and water don’t mix. Wiping your face with a warm towel is more effective than rinsing alone, but only the surface oil is being removed—nothing is binding with the dirt and debris in the pores to get them clean. The proper method involves placing a very hot towel on the face until it cools down, gently wiping the face with the towel, and then repeating (several times if necessary). Though many people can tolerate this treatment, there are many with problem skin that cannot.  Do yourself a favor and consult with your dermatologist before delving into this DIY trend.2. Do Not Make Your Own SunscreenThis is a big no-no! There is more to creating a natural sunscreen than simply mixing zinc oxide and/or titanium dioxide with oil. What’s wrong with this method? Let me break it down for you.Zinc oxide and titanium dioxide are particles that stick together: The only way to break them apart is to use very high shear mixing (sorry, your blender won’t cut it). This makes the sizes uniform and helps with an even application, which is very important for these sunscreens since they work by scattering the UV rays. We are dealing with microscopic sizes so merely looking at it (even with a magnifying glass) or rubbing it on your skin to check for evenness is not going to tell you if you have small, uniform particles. When you mix these without the high shear, you are leaving gaps for the UV rays to get through and have access to your skin.Necessary suspension: Another key element in creating effective zinc oxide and titanium dioxide based sunscreens are using oils that help the particles stay uniform. Some ingredients are compatible with the sunscreens and help the particles stay apart, while some are not and actually force the particles together. Yes, some natural oils have been tested in-vitro (with a machine, not on human skin) and have calculated SPF values but:

  1. The SPF of materials change when mixed with other ingredients.
  2. The final SPF does not add up to the sum of its parts, meaning an oil with an SPF of 4 mixed with a sunscreen with an SPF of 16 does not make the final SPF 20.
  3. How the sunscreen is made influences the SPF just as much as the ingredients.

Now that it’s on your skin, who says that it’s going to stay there? Not only is it important for the particles to stay separated before applying the sunscreen, it’s just as important for them to stay put once you apply them. Without a proper film former, the particles will move around, leaving your skin vulnerable. A thick product does not mean that it will stay put—heat melts waxes so they are not the best ingredients to rely on for keeping the sunscreen in place.I can appreciate a desire to use nothing but the purest ingredients straight from nature to create a sunscreen, but unfortunately, certain ingredients are necessary to make an effective sunscreen that feels good enough for people to want to use it.