MEK testing your nail polish glitter... Why is it important?
It seems that not all nail polish glitters are created equal. When we first started out sourcing glitter and glitter shapes we would get excited when we came across a cute fuchsia dot or square. We would be gung ho and put it in our indie polish only to find that after a day or a week our beautiful white jelly polish had changed to a washed out shade of pink. Not good for the reputation and more importantly not for customers polishes.
Now older and wiser we religiously MEK test all/any glitter we intend to use. Methyl ethyl ketone (MEK) is an industrial strength solvent usually stronger than any nail polish suspension base. That’s why it is ideal for evaluating the long term solvent resistant qualities of any glitter you might be thinking of using.
The accepted wisdom is that if your coloured glitter can sit submerged in MEK for around 5 minutes and not bleed any colour into the MEK then it has passed the test and we can trust it in our Indie polish. We also need to be concerned about our larger glitters curling but that’s another test. For the test we did the above… below you can see the results.
To be fair we should have left the glitters in the MEK for the requisite 5min. But after that time, samples A ,B and C had shown no signs of discolouration. We were confused..WHY? because we had rejected A and C due to them NOT passing the test a month ago. Leaving the glitters submerged for an extra 5 minutes showed that we were right in not selecting them for sale. Slowly the MEK began to turn pink and purple respectively. It was a shame as we really liked those glitters and wanted to stock them. The emerald green glitter was the only one that passed with the surrounding MEK remaining clear as crystal. Even with one of us shaking the hell out of it.
Officially according to the 5 minute rule, all the glitters except Sample D would have passed and been deemed solvent resistant. Though we wonder about the long term reaction between the glitter and the solvent based nail suspending base if those glitters were used in an indie polish. Perhaps someone could purchase an Indie nail polish and not use it for 3 months giving the glitters enough time to bleed. But maybe that’s us being a little too anal..