At this point, making lipstick out of crayons is a bonafide DIY sensation, with hundreds of tutorials littering the internet.
|Image Source: https://www.youtube.com/watch?v=QloxsO9Jy0E|
The most commonly cited reason for using crayons to create lipstick is that lipsticks contain trace amounts of lead. I can wax poetic about how low levels of lead in lipstick isn't a reason to hide in your panic room, but the easiest way to show the silliness of this claim is to write about lead levels in crayons.
According to the Consumer Product Safety Commission (CPSC), crayons contain between 2 and 5 ppm of lead. The CPSC caps lead levels in children's art materials at 100 ppm. This isn't a concern, because children are not eating huge boxes of crayons and because companies are actually staying well below the legal limit… but it's still higher than what you would find in lipstick. According to the FDA, lipsticks average closer 1.11 ppm. So, there's no real benefit to picking crayons as your lipstick of choice.
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There are, however, some noteworthy downsides. Crayons are typically comprised of paraffin wax, which is used in low levels to add a little bit of gloss to lipstick. Unfortunately, because the texture is stiff and brittle, and because it doesn't play nicely with other cosmetics ingredients, you'd be hard-pressed to find a lipstick that is comprised of large amounts of paraffin wax. It's unlikely, then, that crayon-based lipstick will create a lipstick with the texture and color-payoff of a commercially available lipstick.
In addition to paraffin wax, crayons contain pigments. Reasonably, companies like Crayola do not release information about the pigments they use. Unfortunately for crayon-lipstick-makers, that means there is no way to know whether or not the pigments in any given crayon are lip-safe. On their website, Crayola cautions not to use their products on food, such as eggshells (I apparently did Easter wrong as a child… oops…). Although Crayola likely understands that an occasional hunk of crayon will get chewed on, this is still an indication that they are not formulating their product for consistent lip-adjecency. (And why would they?)
Proponents of DIY makeup like crayon lipstick often suggest that creating your own lipstick means you know exactly what is in it, while commercially produced cosmetics are a mystery concoction. In reality, it's the opposite. Crayon lipstick is what you put in it + secret Crayola proprietary ingredients that may or may not be lip-safe, whereas traditional lipsticks have a wonderful, convenient ingredient list.