Magnetic Slime

This little project feels like something out of a sci-fi, which perhaps is why I love it so much. Add some magnetite powder to your next batch of slime, get a strong rare earth magnet, and your kids (or you) will have a blast making zombie worms and magnet eating monsters- straight out of the movies!

Safety: Do not ingest any part of this project. Do not use any of the materials around small children or children who put things in their mouth. Too much iron is poisonous and it should not be ingested in this form. Rare earth magnets are very strong and can pinch fingers, be careful when using them. Magnets should never be left around small children who could ingest them. Do not use magnets near electronics or credit cards. The magnet in the video has a pulling force of 48 lbs. This was more than sufficient. If you are doing this with kids, do not use a more powerful magnet and only use one magnet at a time to avoid pinched fingers.

Materials

Procedure

  1. In a bowl or cup, dissolve the 1/8 tsp borax in 1/4 cup hot water. Set aside.
  2. To a different bowl, add 1/4 cup glue, 1/4 cup water, and 3 tbs iron oxide powder. Mix well. (Note: The powder will stain skin, so try not touch the iron oxide with your hands at this point, wait until the borax solution is mixed it. If you do get it on your hands, dish soap washes most of it off.)
  3. Slowly add the borax solution to the glue mixture and mix well.
  4. Take the slime out and knead with your hands till it is smooth. If it feels sticky, dip it in the extra liquid in the bowl and knead again.
  5. Start playing with the slime and magnet!

The Science Behind Slime

The glue contains a long molecule called polyvinyl alcohol (PVA). It is a polymer, which is a molecule that contains repeats of a subunit molecule (for example, “A” is a subunit and “AAAAAAAAAAAAAAA” is a polymer of A). Borax (sodium tetraborate) is a small molecule that can stick to parts of the PVA through hydrogen bonds. This means one side of the borate molecule can stick to one strand of PVA, while the other side of the borate can also stick to a different strand of PVA, creating a bridge between the two PVA strands. This is called crosslinking.

Having many crosslinking sites usually makes a polymer more rigid, but the interesting thing about borate/PVA crosslinking is that the bond is transient, meaning it can easily break and reform somewhere else. This causes the slime to act kind of like a liquid and kind of like a solid. If given time, the PVA can ‘flow’ as gravity pulls and breaks the borate/PVA crosslinks. It acts like a slime instead of a true liquid because as the PVA molecules pass by more borate, they can momentarily bond to borate and another strand of PVA, slowing down the flow. If you pull the slime fast, you break all those bonds quickly, allowing the slime to act like a solid momentarily.

The Science Behind Magnetic Slime

The iron oxide powder in the link above is magnetite, which is a natural mineral made of iron and oxygen. Like many iron-containing compounds, it is attracted to a magnet.

The iron oxide particles in the powder will become suspended in your slime matrix. As the particles are attracted to the magnet, they will pull the slime matrix with them, causing a whole section of the slime to move with it. This makes for some really cool effects!


If you’re looking for a project to use some of the leftover ion oxide powder, try our DIY Magnetic Shapes!

DIY Magnetic Shapes

I’m always trying to find ways to repurpose supplies I purchase for activities. We have a big bag of magnetite powder we use to make magnetic slime, but I haven’t thought of another use for it…until now! By mixing it with glue and baking soda, you can pipe (like frosting) any design you can think of, and it will stick to a magnet. This is perfect for magnet-on-a-pole fishing games. Read on to learn more!

Materials

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Method

Note: Magnetite powder (an iron oxide) is very messy and should not be touched with bare hands as it stains. Wash hands thoroughly after doing this. Older children may help with steps 3-6, but should always be supervised as any large amount of iron is dangerous to ingest. The dried shapes are safe to handle with bare hands, but the shapes and magnets should not be handled by children who put things in their mouth.

  1. In the ziplock bag, measure in a 1:1:1 ratio the magnetite powder, school glue, and baking soda. Since the first two ingredients are so messy, it is totally fine to just eye-ball the amounts. This is a very forgiving goop.
  2. Squeeze out the air and seal the ziplock bag.
  3. Mix the contents thoroughly by squeezing and mushing.
  4. Snip off a small lower corner of the bag and pipe designs onto wax paper like you would if you were decorating a cake. (Though these will not be incredibly fragile, you don’t want any shapes to have lines with less than ~1/4 inch thickness or they will break with typical child’s play.)
  5. Let dry for 24 hours.
  6. Paint the shapes with paint or nail polish.

Discussion

Magnetite is a natural mineral made of iron and oxygen. It is attracted to a magnet and in some cases can be magnetized to become a permanent magnet. Magnetism was discovered millennia ago by observing metal sticking to naturally magnetized magnetite, called lodestone. Though I haven’t been successful in magnetizing the shapes made by this project, it is possible to magnetize magnetite by placing it in a strong magnetic field (eg. very strong magnet or electromagnet).

The shapes you will make are called magnetically soft, in that they become temporary magnets when exposed to a magnetic field (i.e. other iron-containing things will become attracted to it when it, itself, is in a magnetic field), but if the magnet is removed, the shape becomes unmagnetized.

How to Play

  • Alphabet Fishing (learning letters): We tied a magnet to a wooden pole and went “fishing” for magnetic fish shapes and letters covered by dried rice in a plastic bin. You can use this activity to learn upper or lower case letters, or spelling a name.
  • Fishing for Compliments (learning to read): We made magnetic hearts and I wrote adjectives that complimented my daughter on the back of them (eg strong, smart, kind, etc). She fished for them in a tub of dried rice and black beans and sounded the words out as she found them.

As always, let us know if you’ve tried this on Instagram and Twitter @cara_florance. Tag us and include the hashtag #IBravedTheElements for a chance to be featured!

xoxo

Cara