Thursday, April 17, 2014
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Makeup Microbiology, or “Why dirty Makeup Brushes are disgusting”

​This article was originally published on the 1st of June, 2012.

Editors note: We’ve all done it – used a dirty foundation brush, even if only once in a while. I know I’ll occasionally say to myself “what harm can it do?” and I’ll have a skin breakout a few days later….

When Lizzi first pitched this article to me, I couldn’t be more excited. With her background in Microbiology she was the perfect person to investigate if it really is important to clean your foundation brushes. A big thank-you to Lizzi and her lab for running this experiment for the Makeup Utopia community!


Warning: This article is ‘graphic’ if you don’t want to be shocked into changing your actions, I recommend you stop reading now.

I’m a bit of a germophobe when it comes to makeup brushes, I keep them covered, I wash them often, I won’t use a brush for more than one application before washing it. (Why yes, I do have a GIGANTIC makeup brush collection to allow me this luxury)  I have all my ‘clean’ brushes under zip lock bags and I have a special holder for my ‘dirty’ ones.  When people tell me they don’t wash their brushes, it makes me feel kind on nauseated…Never? Not even your foundation brush? Blergh…

With that, I decided to try and show why I know cleaning my brushes often is actually the best policy.

Enter: scientist Lizzi…

I took 3 identical makeup brushes (no seriously, 3 of the same type, colour, size and everything)

Brush 1: Dirty. Taken from my foundation brush jar, used to apply foundation on Friday morning, left upright, uncovered in a cup on my bathroom bench until Monday morning.

Brush 2: Clean. Taken from my foundation brush jar on the Monday morning.

Brush 3: Clean. Taken from the zipped case on the Monday morning.

All brushes were cleaned in the same way* prior to use.

For interest’s sake, the jar I speak of is actually a straw dispenser:

VLUU L100, M100  / Samsung L100, M100

I will admit I have never sanitized this holder, but being hard plastic, it would be incredibly easy to do.

Into the lab I went, I’ll try not to get to technical but basically I smeared each brush over 2 plates each, for reliability reasons I included a blank (a plate of nutritious agar with nothing on it to show they agar was sterile prior to me brushing it up!)

VLUU L100, M100  / Samsung L100, M100

The brushes, you can see the left is the ‘dirty’ brush, the middle is the one from the jar, both brushes were placed in brand new (an because its designed for use with food, I assume sterile) zip lock bag for transport.  The right hand brush is in its nifty zip up case.

VLUU L100, M100  / Samsung L100, M100

As you can see, on the far left is my blank, then the ‘dirty’ brush and its plates, the ‘jar’ brush and its plates and the ‘case’ and its plates.

VLUU L100, M100  / Samsung L100, M100

All the plates are then stacked and wrapped in glad wrap ready for incubation.

VLUU L100, M100  / Samsung L100, M100

This is the bundle of plates prior to going in the incubator, the 26 is the date they were to come out of the incubator and of course my name is all over it so if for some reason I forgot them, the awesome micro techs could call and remind me- They didn’t have to, but they are still awesome.

The Results

This is where it gets gross.

First, the blank:

Makeup Microbiology 6

Clear plate, nothing has grown, this means that I can assume there was no contamination of the media (the stuff I’m growing the germs on) either by human error (me sticking my finger in it) or through environmental contamination (the plate, and/or air surrounding the pouring of the media was dirty)

Next the ‘case’ brush:

Makeup Microbiology 7

At the end of the arrow you can see 1 growth, on one plate, none on the other.

Next the ‘jar’ brush:

Makeup Microbiology 8

You can probably try to count these and you will find 8 on one plate and 10 on the other, I expected this (or rather the micro supervisor had told me, I should expect a rude shock), and it’s a good warning that I should sanitize that jar.

In true tradition, I have of course saved the best for last.

The ‘dirty’ brushes:

Makeup Microbiology 9

Yeah, that’s truly gross, that big growth is what is known as a spreader…. yummo, now imagine forcing all that into your face by way of a dirty brush.  I will admit, this is not what is on your brush, this is an accelerated growth of what is on your brush, but all growths have come from the bacteria present.  This was 1 use, and 3 days standing in a bathroom, now think if it was every day use and thrown into a makeup bag, how much worse this could be.

Just for funsies, here are some other shots of those really lovely plates…I put these on the colony counter (a back lit box to allow easy viewing to could the number of growths)

Dirty Brush:

Makeup Microbiology 10

Makeup Microbiology 11

And some really lovely close ups of those brush germs…

Makeup Microbiology 12
Makeup Microbiology 13
Makeup Microbiology 14

So, hands up who’s going home to wash their brushes? And who is never using a brush again???

*I personally wash my brushes with anti-bacterial washing up liquid and then spray with alcohol.  I also tend to rub my foundation brushes with an alcohol wipe-like the ones they use in the doctors, prior to an injection- before using them, I don’t have sensitive skin, so this has never causes a problem, I also find the slight moisture left on the brush aids in the application of foundation, but hey, that’s just me.

Editors note: If you’re all freaked out and want to know how to clean your brushes, check out Lizzi’s great follow up article HERE.

About Lizzi

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