What is oobleck?
Oobleck is a non-Newtonian fluid made from corn starch and water. When you mix the two together, it forms a solid-like material that acts like a liquid when force is applied. The name “oobleck” comes from a Dr. Seuss book, Bartholomew and the Oobleck, in which a gooey green substance called oobleck falls from the sky and wreaks havoc on a kingdom.
Oobleck is popular among kids and science enthusiasts because of its unique properties. When left alone, it has a solid, moldable consistency similar to clay. But when squeezed or stirred, it suddenly becomes liquid-like and will ooze between your fingers. The moment you stop applying force, it reverts to its semi-solid state again. This is due to its non-Newtonian nature – its viscosity changes under pressure.
What causes mold growth?
Mold is a type of fungus that grows via thread-like roots called hyphae. It produces spores that are spread through the air and can settle on organic materials like food, plants, wood, and fabric. If the conditions are right, these spores will germinate and develop into the fuzzy splotches we know as mold.
For mold to grow, it requires:
- Organic material – Mold must have a food source to feed on. This is often provided by things like dust, wood, paper, or natural fibers.
- Moisture – Mold thrives in damp environments. The moisture is essential for spores to germinate and grow.
- Oxygen – Like all organisms, mold needs air to survive.
- Warm temperatures – Most molds grow best in warmer conditions between 40-100°F.
With the right combination of these elements, mold can spread rapidly. It secretes digestive enzymes onto its food source which break down organic material into simple molecules. These are then absorbed as nutrients to help mold propagate and produce more spores.
Does oobleck provide conditions suitable for mold growth?
At first glance, oobleck might seem like a potential breeding ground for mold. Its key ingredient, corn starch, is an organic, plant-based material. Oobleck also contains a good amount of moisture in the form of water. And if left out at room temperature, it would provide warm conditions conducive to mold.
However, there are a few reasons why oobleck does not tend to get moldy:
- Lack of nutrients – While corn starch is organic in nature, it does not contain many complex sugars, proteins, or other nutrients that mold relies on. Mold prefers materials like wood, fabrics, or food waste that provide richer sustenance.
- Low moisture content – Pure oobleck made with only corn starch and water does not have a very high moisture content. Usually the water content is only 20-30%. This drier environment makes it difficult for mold to colonize and thrive.
- Density – When left at rest, oobleck is quite dense and thick. This can restrict the amount of oxygen exposure needed for prolific mold growth.
So while oobleck meets some of the basic requirements for mold, it does not provide ideal conditions. Its low nutrient content, drier composition, and dense texture prevent extensive mold growth.
Are there any scenarios where oobleck could get moldy?
There are a few specific situations where oobleck might be more susceptible to mold:
- If left in an area with very high humidity like a damp basement, the extra moisture could promote mold growth.
- Adding excess water when mixing oobleck reduces its viscosity and makes it thinner, allowing more air penetration and potential for mold.
- Storing oobleck long-term allows more time for mold to eventually take hold, especially if kept in humid conditions.
- Mixing additional food items like fruit or sugar into oobleck provides more nutrients for mold.
- Getting contaminants like food residue or dirt mixed into the oobleck inoculates it with mold spores.
So while pure, freshly-made oobleck resists mold well, environmental factors or ingredients can increase the risk over time. Oobleck made in non-sterile conditions and left for weeks or months may eventually show some mold growth.
How to prevent oobleck from getting moldy
Here are some tips for keeping oobleck free from mold:
- Use clean, dry ingredients – Make sure your corn starch and water are as mold-free as possible.
- Mix in a clean environment – Avoid mixing oobleck in damp, humid, or dirty areas which can introduce mold spores.
- Store in an airtight container – This minimizes air exchange and humidity that could promote mold growth.
- Refrigerate oobleck – The cold temperatures of the fridge will inhibit mold growth.
- Use within a few days – Fresh oobleck resists mold better than old, long-stored batches.
- Keep play surfaces clean – Quickly wipe up any spills or residue that could transfer dirt and mold to the oobleck.
- Avoid adding high-nutrient mix-ins – Ingredients like juices, fruits, or sugars will feed potential mold growth.
Proper mixing and storage practices can help minimize the chances of oobleck developing mold. Discard any batches that show obvious fungal growth. Remaking fresh oobleck regularly is the best way to enjoy its unique properties mold-free.
Can moldy oobleck make you sick?
In most cases, a small amount of mold growth in oobleck is harmless. However, large amounts of mold or mold spores can cause illness, especially for people with allergies or asthma.
Symptoms of toxic mold exposure can include:
- Wheezing or difficulty breathing
- Runny nose and watery eyes
- Red, itchy skin or rashes
- Sore throat or coughing
- Headaches, fatigue, or dizziness
- Fever or flu-like symptoms
Very high levels of toxic black mold exposure can cause much more severe reactions. People with a mold allergy should be especially careful and avoid contact.
If oobleck exhibits extensive mold growth, it is safest to just throw it away. Oobleck is cheap and easy enough to remake a fresh batch as needed. Trying to salvage moldy oobleck is not worth the potential health risks.
Can you save moldy oobleck?
While not recommended, it is possible to try and save slightly moldy oobleck if you take proper precautions:
- Wear gloves, mask, and eye protection when handling – Avoid touching mold with bare hands or inhaling spores.
- Remove and discard the worst mold spots – Scoop out any areas with concentrated fuzzy mold.
- Mix in some baking soda – This can help inhibit further mold growth.
- Add a bit of bleach – About 1 teaspoon per cup, bleach can kill mold spores.
- Heat it – Carefully microwave or simmer on the stovetop to kill mold.
- Quickly re-use – Mold may still return, so use up treated oobleck fast.
However, this is still risky. Mold can be difficult to remove completely from porous materials. Oobleck with any hazardous black mold should not be salvaged and should be discarded. Preparing a fresh, clean batch is the safest option.
Frequently Asked Questions
Can oobleck grow anything else besides mold?
Oobleck is not a very hospitable environment for most biological growths besides some mold species. Its dry, dense composition prevents most bacterial or fungal growth. However, oobleck made with nutrient-rich additives could potentially allow growth of yeasts or other fungi over time. Proper storage is still important for any homemade oobleck.
Does oobleck expire or go bad?
The corn starch and water in pure oobleck do not expire or go truly bad. However, over time, dried out batches may become unusable. Excess drying can cause oobleck to harden irreversibly. Also, contamination with food, dirt, and mold eventually make old oobleck undesirable for play. For best results, use oobleck within 1-2 weeks and remake fresh batches as needed.
Can oobleck grow bacteria like salmonella or E. coli?
It is highly unlikely for plain oobleck made from corn starch and water to support significant bacterial growth. Salmonella, E.coli, and other foodborne illness-causing bacteria require nutrient-rich environments found in foods, not the starch and water in oobleck. Proper kitchen hygiene when mixing ingredients minimizes any bacterial contamination as well.
Is black mold in oobleck dangerous?
Yes, certain Aspergillus mold species that produce black mold colonies are considered toxic and can cause severe reactions. Stachybotrys chartarum, known as “black mold”, produces mycotoxins that can be very harmful if inhaled or touched. Oobleck showing any growth of dark black mold should be handled with extreme caution and likely discarded.
Conclusion
While oobleck itself does not provide ideal conditions for prolific mold growth, environmental factors like moisture, humidity, and contaminants can allow some mold to develop over time. Freshly prepared oobleck resists mold well. But improper storage, excess water, and nutrient-rich additives increase the risk of eventual mold growth in old batches of oobleck. Completely preventing mold on oobleck is difficult, so it is recommended to enjoy fresh mixtures within a week or two and remix as needed. Proper precautions are advised if handling oobleck with extensive mold growth, especially toxic black mold varieties, to avoid health issues.
