How Does It Work? Black Spotted by Opi
We’ve already talked a little bit about a proposed mechanism for crackle nail polish. This effect is similar, but less ubiquitous and more interesting.
Opi’s Black Spotted is a special effects nail polish that enjoyed a limited release in Sephora stores in France. Like crackle nail polish, it has its effect by selectively revealing the color underneath. But, instead of cracking, Black Spotted creates a bubble-like effect that almost reminds me of a disease.
Because of its unique appearance and limited release, people went ballistic, eager to get their hands on this fancy new polish. Ebay sellers who could get their hands on a bottle were retailing it for up to $100. (That’s more expensive per ounce than printer ink!) At the time of this posting, there are still a few ebay sellers trying to charge $60-$70 for 0.5oz of this stuff.
|There are lots of beautiful pictures of Black Spotted manicures, but I especially like this one by Nailderella.
You can read her full post here: http://nailderellanails.blogspot.com/2012/06/opi-black-spotted.html
I decided to investigate the mechanism of this fabulous effect. Unfortunately, there are very few resources that help give insight.
Luckily, a blogger called Peek-a-Polish thought to upload the picture of the ingredients.
Ingredients: Ethyl Acetate, Butyl Acetate, Heptane, Nitrocellulose, Water, Adipic Acid, Acetyl Tributyl Citrate, Isopropyl alcohol, benzophenone-3, Styrene, Sodium Magnesium Silicate, Phenoxyethanol, Methylparaben, Ethylparaben, Butylparaben, Isobutylparaben, Propylparaben.
Ethyl acetate and butyl acetate are common solvents in nail polish. But heptane? Heptane? That’s the third ingredient? That’s very unconventional and almost certainly not coincidental.
Heptane is a straight-chain alkane with seven carbon molecules. An alkane is a type of hydorcarbon (meaning it contains only carbon and hydrogen) that is fully saturated (meaning that there are only single bonds– every carbon atom is bound to four other atoms). Heptane (along with all alkanes) is non-polar.
The other odd thing that I saw on the ingredients list was water. Water is not commonly found in nail polish. Water molecules, with their two shared electron pairs, is in a bent formation and, thus, is polar.
In chemistry, a good rule of thumb is that “like dissolves like”. This means, of course, that two unlike substances will not mix. A nonpolar substance, like heptane, and a polar substance, like water, will repel each other, leaving you with puddles of water left on your nail, which creates the effect you find in Opi’s Black Spotted.
Putting It To the Test
To confirm my hypothesis, I decided to see if I could recreate the effect of Opi’s Black Spotted. You should NOT try this at home for personal safety reasons.
However, on the off chance that you are bad at following directions and do attempt this, please remember that heptane is not good for you. Be careful and smart so you don’t hurt yourself. Also, since you are not adding additional preservatives, be sure to trash your creation once you make it, lest it start festering with weird, unpleasant bacteria. Also don’t do it at all. But if you do try it, at least do that.
|“Heptane, flammable, harmful”|
I took a jug of n-heptane and some anonymous Halloween-themed drugstore nail polish as my sacrificial victim. I also took a bowl of water.
Next, I started my very un-methodological task of figuring out the correct ratio of polish to water to heptane.
Too much heptane gave me weird, unusable clumps.
Too much water gave me very little bubbles.
Unfortunately, those little bubbles didn’t translate into an effect on the nail. It just looked lumpy.
As Goldilocks would say, “Just right”. Well… kind of.
The end result was clumpy, ugly and inelegant. It seems the proportion of traditional nail polish ingredients is also important in creating a usable product. However, the effect of bubbles was definitely created, indicating that my proposed mechanism successfully accounted for the appearance of this special effect polish.
|Over Sinful Colors Fusion Neon|
Sadly, it seems that starting with an already-made polish will not create the gorgeous special effects Black Spotted- coveters crave. Still, it gave insight on the mechanism, which is fantastic enough on its own!