How to Make Oobleck Without Cornstarch

Using Arrowroot or Tapioca Powder

Pour 1½ to 2 cups (190 to 250 g) of your powder into a large bowl. Arrowroot powder and tapioca powder are both popular substitutes for cornstarch when it comes to cooking. When it comes to oobleck, you can use them in the exact same way as cornstarch without any modifications. You can try baby powder, but it must have cornstarch in it. Read the ingredient label to make sure. You can also try potato starch, but don't use baking soda or flour. Baking soda will just fizz while flour will turn into paste.

Add 1 cup (240 mL) of room-temperature water. Don't worry too much about the amounts just yet. As long as the proportions are similar, you should be good. Remember, you can always make adjustments later. The original recipe calls for 2 parts cornstarch and 1 part water. Arrowroot powder, tapioca powder, and potato starch are all direct substitutions. To make your oobleck look more interesting, add some food coloring into the water. Start with 2 to 3 drops, then add more until you get the color you want.

Mix the oobleck with your hands or a rubber spatula. Either will work just fine. If you don't have a spatula and don't want to get your hands messy, pull on a pair of plastic gloves first. Mix the oobleck until the ingredients combine. At this point, it should start behaving like a non-Newtonian fluid.

Add more powder or water, if needed. This is mostly up to your preferences. Ideally, oobleck should flow like water when left alone, but act like a solid when pressure is applied to it. If it isn't quite to your liking, try the following: If the oobleck is too watery, add more powder. If the oobleck is too hard, add more water.

Store the oobleck in a sealed container when you aren't playing with it. A plastic box, jar, or zippered baggie will work just fine. Keep in mind that oobleck will eventually dry out after a couple of days. You may be able to bring it back by adding some warm water to it, however.

Discard the oobleck into the trash, not the sink. If you toss the oobleck into the sink, it will clog the drains. Instead, put it into a plastic, zippered baggie. Zip the bag shut, then toss the bag into the trash. You should still do this even for dried out oobleck. This is because it can get rehydrated in the drain the next time you turn on the water.

Using Cornflour

Place 16 ounces (450 g) of cornflour into a large bowl. Make sure that the bowl is large enough to hold 16 ounces (475 mL) of water as well. You will be mixing everything in this bowl. Use a kitchen scale to measure out your cornflour. Cornflour is essentially the same thing as cornstarch, but with a different name. There are some differences, however, in terms of amounts and water temperature. Make sure that you get cornflour and not corn flour. Cornflour is more powdery than corn flour, which is grainy, like corn meal.

Stir some food coloring into 16 ounces (475 mL) of hot water, if desired. You don't have to do this, but it will make your oobleck look more interesting. How much food coloring you use is up to you; the more you use, the darker the color will be. Start with just 2 to 3 drops, then give the water a stir. If it's not dark enough for you, add more food coloring. If you skip this step, the oobleck will be white. This is perfectly fine if that's what you want.

Pour the water into the cornflour. Here is where the biggest difference between cornstarch and cornflour occurs. With cornstarch, you want to use half the amount of water as your cornstarch. With cornflour however, you want to use the same amount of water. The water should be hot, unlike for cornstarch.

Mix the water and cornflour with your hands or rubber spatula. Keep mixing the ingredients until they come together and the oobleck feels like honey. If you are using your hands and added food coloring, it might be a good idea to wear plastic gloves. Food coloring can stain skin, so the plastic gloves will help keep your hands clean.

Add more water or cornflour, if desired. This is really up to you depending on how thick or thin you want the oobleck to be. If you want the oobleck to be thicker, add more cornflour. If you want it to be thinner, add more water. Be sure to mix the oobleck well after each addition.

Keep the oobleck in a sealed container when you're done playing with it. Plastic, zippered baggies, containers, or jars will all work just find for this. Keep in mind that the oobleck may still dry out after a couple of days. If that happens, add some warm water to it; this may bring it back.

Place the oobleck into a plastic bag before throwing it away. Never toss oobleck into the sink as this can clog the drain. Instead, put it into a plastic, zippered bag, then throw the bag into the trash. Don't toss dried oobleck down the drain either. The next time you use the sink, the oobleck might get rehydrated and clog the drain.