Does Oobleck Go Bad

In this brief article, we will answer the question, “does oobleck go bad?”, and will address some more facts about this playtime exclusive, such as does oobleck rot, does it dry out, how you should store it, and how to make a batch. 

Does Oobleck Go Bad?

Yes, oobleck can go bad, dry out, and even rot, and usually remain its best for just about a day. However, this will depend on its storage conditions.

Does Oobleck Expire?

Yes. Even if it is stored under appropriate conditions, oobleck is a food product and will therefore expire after some time. Oobleck is a dough with a high water activity. This allows the growth of bacteria (1).

After the recommended period, it is strictly recommended that you dispose of the oobleck to make sure that children (especially toddlers) do not play with it or accidentally ingest it.

Is It Dangerous to Consume Expired Oobleck?

Even though it is not life-threatening to consume expired or ‘bad’ oobleck,  it can result in stomach discomfort and intestinal pain. That is because it can contain microorganisms or toxins produced by microorganisms (1). However, these symptoms generally subside on their own after a few hours. If color paint was added to the oobleck, it can cause intoxication due to the presence of heavy metals. Symptoms can include hives, itching, flushing, swelling, sneezing, runny nose, cough, wheezing, shortness of breath, chest tightness, nausea, dizziness, or lightheadedness (2).

To keep track of the longevity of oobleck, it is highly recommended that you either mention the date of when the oobleck was made on its container, or you record the date in a notebook and keep it somewhere near the stored oobleck.

Can Oobleck Grow Mold?

Yes. Since oobleck is a food product, it can grow mold. Especially if stored under unsuitable conditions, the oobleck will begin to grow mold three to four days after being made. When the surface of the oobleck starts to dry out, it becomes conducive to mold growth (1).

During these days, the oobleck may not appear bad or spoiled, but it may be growing spores within it that cannot be seen by the naked eye. If ingested, these spores can be extremely dangerous to health. The foodborne bacteria Bacillus subtilis spores may naturally contaminate cornstarch and subsequently germinate and grow during storage (1).

When stored properly, the process of developing mold slows down and the oobleck can be safely played with for a longer time. However, even if it is stored properly, oobleck can start growing mold if it is kept for too long, the reason being that it is ultimately a food product and all food products eventually grow mold after some period. Even if stored properly, the surface will start to dry and mold will grow on the surface. Besides, bacteria may grow inside the dough (1).

Can Oobleck Dry Out?

Yes, oobleck will eventually dry out if left in the air for a couple of hours. To prevent this from happening, keep adding water to it and make sure the oobleck remains hydrated. Moreover, it needs to be stored properly to prevent it from becoming brittle or rotting, but more on that later. 

Oobleck is a cornstarch dough. After being hydrated, the starch is partially gellified and may undergo retrogradation. Starch retrogradation refers to the reassociation or the recrystallization of the polysaccharides in gelatinized starch, ie, amylase and amylopectin. It occurs when the starch-based systems or foods are exposed to freeze/thaw cycles, or when moisture migration occurs in starchy foods, impacting their textural attributes (3).

However, drying out is one of the advantages of this product, since drying makes it extremely easy to clean up after the kids are done playing with it. Dried oobleck turns into corn starch, which can easily be vacuumed or swept off surfaces like marble or carpets.

DO NOT reuse the dried corn starch already used to make oobleck for any other purpose, since the corn starch could be thriving with germs accumulated from previous play sessions.

How Should You Store Oobleck?

Oobleck must be stored in an airtight, tightly sealed container and ideally placed in the fridge. It is preferred that you put the container of oobleck on the top shelf since this is the coldest area of the fridge (4).

As we’ve mentioned before, keep a notebook with the date you made the oobleck near it for easy access and to estimate its longevity. 

Also, keep adding some water to the oobleck every day to prevent it from drying, the oobleck will last for about two weeks with this practice, after which you must discard it.

How Do You Dispose of Oobleck?

To dispose of oobleck, add a generous amount of water and turn it into a slurry. Run some hot water, and just pour the mixture down the drain. The hot water will dissolve the corn starch and prevents the slurry from clogging the drain.

How Do You Make Oobleck?

Here’s what you need to make a batch of oobleck:

  • Two cups of cornstarch/white cornflour 
  • One cup of water
  • Food coloring (Optional)
  1. Mix the cornstarch and water in a large bowl. Keep mixing until you achieve your desired consistency. If you want to add color, mix the food color and water before you add the cornflour. 
  2. If the mixture seems too watery and isn’t forming into a solid oobleck, add some more cornstarch. Alternatively, if the oobleck seems too hard and inflexible, aad some more water. Remember: the key to perfect consistency is experimenting.


In this brief article, we answered the question, “does oobleck go bad?” and addressed some more facts about this playtime exclusive, such as does oobleck rot, does it dry out, how you should store it, and how to make a batch. 

If you have any more questions or comments please let us know.


  1. Rahman, M. Shafiur, ed. Handbook of food preservation. CRC press, 2007. 
  2. Martin, Sabine, and Wendy Griswold. Human health effects of heavy metals. Environ Sci Technol briefs cit, 2009, 15, 1-6.  
  3. F. Kong, R.P. Singh, in The Stability and Shelf Life of Food (Second Edition), 2016
  4. How creepy. The University of Akron.