Raymond forwarded me this link on Instructables - Homemade Sunscreen - and I have to rant about it!
Please don't think me bitter or mean! Someone eager to make lotion will try this and be disappointed and never try it again, and they've lost out on the joys we have found! Or they'll get a horrible sunburn. Or get covered in some kind of hideous bacteria growing in the mixture. I am very passionate about this topic - it's easy to find good instructions for making products, so why pass along misinformation?
I've tinkered with the idea of making my own sunscreen - I have all the ingredients and Raymond has vitiligo, so it would save us a fortune every summer - but there's no way I would know if it were effective, and who wants to be the test subject when the possibility of agonizing sunburn-y pain could be the result?
But I'm going to put that aside for now and move on to the other bits that are bothering me.
The recipe suggests using 8 ounces (240 grams) of carrier oil, 1 oz (30 grams) e-wax, and just under an ounce of titanium dioxide (30 grams). So we have 10 ounces with 10% being e-wax. There is no water in this recipe. So why the e-wax? And why so much? The explanation is that it makes it thicker...so why not use a butter? E-wax is really not relevant in a non-water based product, unless it's something like an anhydrous sugar scrub or body bar you want to turn into a lotion when you're in the shower.
If you really wanted to make this product - which I do not suggest, and note that you do it at your own peril - then why not a lotion bar? Or what about some nice oils with a little butter and maybe a little wax thrown in to make it thicker? Or a whipped butter? There are many ways to thicken an oil with waxes and butters: E-wax would be one of my last choices!
And please do not use citrus based essential oils in products meant to be worn in the sun. They will make you photo sensitive, leading to pain, misery, and a lot of "oh why did I go in the sun today" kind of moaning! If you must have a citrus based fragrance in your products, consider using a fragrance oil that won't make you sun sensitive. Lavender is supposed to be soothing for apres sun exposure.
Then this poster links to a site on how to make your lotions last more than 3 months. You cannot make lotions in 15 minutes - the heat and hold process takes at least 20 minutes, and you need to take time to get the ingredients up to temperature - and preservatives are necessary. (You can get away without preservatives in an anhydrous recipe, but I always suggest using Vitamin E to retard rancidity). She notes you don't have to follow "complicated industry guidelines of manufacturing" to increase the shelf life of your products. Those guidelines are there for a reason. Few of us can afford to sterilize our equipment, but taking the time to heat and hold, using distilled water, and preserving well isn't a luxury; it's a necessity so we know our products are safe!
Making lotion isn't rocket science (it's cosmetic science!) and you don't need a complicated recipe to make one. (Click to see my post on Lotions: Is it a good recipe?) The advice against making your own sunscreen is about efficacy, and we have no way to test that at home. The advice for good manufacturing practices is about keeping ourselves, our loved ones, and possibly customers safe and not infected with icky things that can grow in unpreserved lotions.
If you want to try a zinc oxide cream - very nice if you've had a little too much fun in the sun - may I suggest this recipe from Voyageur? (Scroll down to see the recipe.) I've used it for soothing various problems and I like it! I did tweak mine to include 10% aloe vera - good for post sun exposure - and more hydrolyzed protein (2% instead of 0.6%). I also included 2% panthenol - again, good for damaged skin. Feel free to switch the stearic acid for cetyl alcohol for a slightly less thick but more glide-y product.
And invest in some good sunscreen. Yeah, it's going to cost you money, but better money out of pocket today than sunburn pain tomorrow or skin cancer in the future.
Thus endeth the rant...