College Life, Science

Science at Home

Science is fun! As I am learning in class, I decided to do a few experiments at home on my own. I am a nerd after all.

Have you ever wondered just how clean your sink is? What about the sponge? Does it really get cleaned in the dishwasher? How many germs are on a fingerprint? How gross and contaminated does makeup get?

Let’s find out!

*Be sure to check back and refresh this page overtime, as I will continue to add more photos and data. I will also inspect the colonies under the microscope to see what type of bacteria has grown.

Teenagers’ finger prints in 24 hours:
One teenager was fresh out of the shower but with touching their phones and face, this is the result of a surprise fingerprint culture. Keep in mind, people don’t usually clean their phones or video game controller. I have seen various statistics ranging from 16-23 times per hour that we touch our face. You can see in the first 24 hours there is a little growth for each teenager. After 48 hours, it’s pretty surprising just how dirty a fingerprint is.

24 Hours
48 Hours
Day 4

24 hours later: Who has a dirtier mouth? Cat, dog, or human?

In the first 24 hours:

1) Dog has the dirtiest mouth
2) Then the human
3) Surprisingly, the cat has no growth

The human sample has smaller, tiny speckles. The cat has no growth on day one. In 48 hours, growths pick up a little and the cat starts to have small growths, but very minuscule. The dog, did he drink out of the toilet!? Ew. On day 4, the cat’s sample has shown growth.

24 Hours
48 Hours
Day 4

Dishwasher Sponge vs. Dirty Sponge:

24 hours later: the dirty sponge is clearly growing but surprisingly, the freshly cleaned sponge from the dishwasher also does have some growth, though minimal. Please ignore the condensation in this plate.

After 48 hours, the dishwasher cleaned sponge is clearly not very clean.

24 hours
48 hours
Day 4


The top right are colonies from inside the toilet, right near the water in the toilet. The bottom sample is taken from multiple areas of the bathroom countertop/sink area, which is next to the toilet. The toothbrush sample (top left) is fortunately not growing. This is why you should clean your sink and countertop regularly (and toilet).

Luckily after 48 hours the toothbrush is still not showing growth. However, the sink surface, which gets wiped down a couple times per week, is clearly growing bacteria. This is where some people place their phone, makeup, wallet, and other toiletries.

24 Hours
48 Hours
Day 4

Used Makeup (6 months old)

Samples from two different mascaras, one matte liquid lipstick, and a shimmery tinted lip balm. For the first 24 hours, there was no growth. On day two, small growths appeared.

48 Hours: Mascara
Day 4: Mascara
48 Hours: Lips
Just one small growth on the lip balm (right) but not lipstick.
Day 4: Lipstick & Lipbalm

Vacuum Dirt

My previous vacuum broke so I bought a new one. I used my new vacuum once after doing a routine clean. I have terrazzo floors, which mean frequent moping and daily sweeping. I can’t stand the feeling of dirt on the floor and can be obsessive. I was curious after dumping out the dirt: how gross is this? I grabbed a sterile inoculation loop and swabbed the inside residue of the vacuum.

I am beyond disturbed about how gross household dirt is!

24 Hours
48 Hours
Day 3

Gas Station Pump, Car Keys, and a Grocery Store Conveyer Belt

I am THAT weirdo who swabbed the gas station pump handle. I already got gas earlier but didn’t have my supplies. On my way to run an errand I pulled in to a very busy and popular gas station. I did not touch the handle but simply hopped out of my vehicle and swabbed it, then I left.

I swabbed my own keys, mostly covering my car and house key they are frequently touched.

At the grocery store, I saw some wetness on the conveyer belt and it ran through. I did not put my groceries down yet and assume this was from something cold. I got a good sample swab of the moist areas and the dry areas to make sure I had variety. Once again, I am a weirdo.

In 24 hours, the only growth came from the gas station pump. In 48 hours, two different colonies (also from the pump handle) grew. Surprisingly the keys and grocery conveyer belt seem clean!

48 Hours
72 Hours
72 Hours (Close Up)
Day 4

Sneezing with or without a mask

The sneezes where on different days due to the difficulty of timing a sneeze. It is much harder to sneeze on demand. The sneezes both came from me. The mask was with a homemade cloth mask. It was very loose fitting in the chin area so I imagine the droplets came from there, not having a snug fit. The sneezes were both approximately 2 feet from the dish. It was pretty interesting to see at least three various types of colonies produced from the direct sneeze. The masked sneeze did minimize exposure but there was still some. I imagine these result would vary with different types of masks.

No Mask Sneeze – Day 3
With Mask: Day 3
Close up of non-masked sneeze colony

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