Water Beads Polymer Lesson {Polymer Play}

Continuing our fun with polymers, I thought I would introduce the little ones to a very different type of polymer – the water bead. These are basically polymers which when in their dried state will absorb copious amounts of water and swell from the size of a tiny bead to the size of a marble. I ordered mine off Amazon for 99p. I hope you enjoy my water beads polymer lesson. If you have any questions, please do email me using the contact box above.

What Are Water Beads?

Water beads are superabsorbent polymer crystals that expand significantly when soaked in water. They are also called water gels, gel beads, sensory beads, and water crystals, among other names. While they are popular for decorative and play purposes, safety agencies worldwide have issued warnings about the serious health risks they pose to children. Please read this very important warning before you let your children use these for their play. I was with my girls the whole time and made sure to warn them not to put any balls near their mouth. As an extra measure, we counted the beads at the beginning and the balls at the end. As we have pets, we wanted to make sure they didn’t go missing and then have our dog or cats wolf them up.

Warning: Risks to Children and Vulnerable Adults

Authorities, including the UK’s Office for Product Safety and Standards (OPSS) and the U.S. Consumer Product Safety Commission (CPSC), strongly warn against letting young children under 5 years of age have access to water beads. They also advise that vulnerable adults should only use them under strict supervision.

Ingestion risks: If swallowed, water beads can absorb bodily fluids and swell up to 400 times their original size inside the body. This can cause life-threatening intestinal blockages that require surgery. The beads do not show up on X-rays, making them difficult to diagnose.
Other risks: If ingested, the beads can also lead to choking and suffocation, or vomiting and stomach pain. If inserted into the ear, they can cause pain, hearing loss, and damage to the eardrum.
High appeal to children: When hydrated, water beads are brightly coloured, squishy, and cool to the touch, which makes them very appealing to children. Tiny, dehydrated beads are also easy to miss if spilled and can be ingested without detection.
Toxicity: While often marketed as “non-toxic,” some water beads have been found to contain concerning levels of the chemical acrylamide. However, the most significant danger is their ability to expand and cause internal obstruction.

Properties of Water Beads

Water beads are super-absorbent polymer balls that swell significantly, up to 400 times their size, when submerged in water. Key properties include their ability to absorb and retain large amounts of water through a process of osmosis, their viscoelasticity (behaving as both a solid and a liquid), and their potential to shrink if they lose water. They are colorful, soft when hydrated, and can be dried out to return to their original, tiny size.

Physical properties

Absorption and swelling: Water beads are made of a super-absorbent polymer, typically a cross-linked polyacrylate. When placed in water, the polymer network absorbs liquid, causing the beads to swell to many times their original size.
Elasticity: They are viscoelastic, meaning they have both elastic and viscous properties.
- Elasticity: They will deform under stress but can also return to their original shape after the stress is removed.
- Viscosity: The speed at which stress is applied affects the amount of deformation. Applying stress too quickly results in less deformation because the bead doesn’t have time to fully respond.
Reversibility: The swelling is reversible. The beads will shrink back to their original size when they dry out, and their size can also be reduced by exposure to high ionic strength solutions.

Chemical properties

Polymer composition: They are made of superabsorbent polymers (SAPs), such as sodium polyacrylate, which have a strong affinity for water through hydrogen bonding.
Osmotic potential: Water enters the polymer network via osmosis, driven by the concentration gradient between the water outside the bead and the hydrophilic groups within the polymer.
Toxicity concerns: Some water beads contain acrylamide, which can be toxic. See above for safety precautions.

Extend Learning! We explored the polymer slime to discover its properties which are very different to the properties of water beads

Common Uses of Water Beads

Water beads have several applications outside of being a children’s toy.

For plants and floristry: They help plants and flowers retain water by slowly releasing moisture to the roots. They are often used as a soil substitute for some plants, such as bamboo, and as a decorative element in flower vases.
For decoration and events: Their vibrant, translucent, gem-like appearance is used to create colorful centerpieces for weddings, parties, and other events. They can be layered in vases with flowers or floating candles, and some people add submersible LED lights to enhance the glow.
Sensory and craft activities: Due to their unique texture, water beads are often used in sensory bins for play. They can be sorted by colour, bounced, or mixed with other materials like shaving cream for extra fun.
As absorbent filler: In their dry state, water beads are used as an absorbent material in household items like disposable diapers and sanitary napkins.

Discover more! We also made another polymer called oobleck from corn flour and water. Its properties as a non-newtonian solid are even more obvious in oobleck than slime

How to Prepare and Care for Water Beads

Preparation:

Pour a small quantity of the tiny, dry beads into a large container. Add a generous amount of water. Check the package instructions for the specific ratio. For example, some recommend 1 teaspoon of beads for 3 cups of water. Allow the beads to soak for 4 to 8 hours, or until they have grown to their full size. Once expanded, drain any excess water using a strainer.

Storage:

If you plan to reuse the beads, you can let them fully dehydrate by spreading them on a towel. Once tiny again, store them in a sealed bag or container out of children’s reach. To keep them hydrated, store them in an airtight container or ziplock bag. If you notice any mold growth, dispose of the beads immediately.

Disposal:

Do not dispose of water beads down a drain or in the toilet, as they can expand and cause blockages. You can put them in the trash, where they will biodegrade over time. Some people crumble them up and add them to potted plant soil.

Book Unit: Yellow Ball: Here we made two versions of a bouncy ball using polymers

Water Beads Polymer Lesson

As usual I organised a tray each for the girls, ensuring they could do everything independently. I popped the desiccated water beads into a beaker and filled the conical flask full of water. I had some more water on stand by just in case we needed it:

Look how tiny the balls are!

The girls added the water to the balls. We needed to leave the balls over night, so make sure you have other things for them to do in the mean time as children aren’t known for their patience! Also, make sure to store the trays out of reach of the children as per safety requirements above.

When they came down the next morning, they were enormous! I let them play with them for as long as they wanted. This was very child led play but again, I was with the girls the whole time to ensure their safety.

Abigail, age 4, exploring during our water beads polymer lesson: