5 reasons closed-cell sponge rubber is the best non-toxic playground surface

Playground surfacing is the most critical aspect of a playground, even more so than the structure itself. With over 200,000 playground injuries reported each year, parents and schools are discovering that recycled materials and wood mulch might not be cutting it. 

Rainbow Mulch is a non-toxic playground mulch manufactured in Ohio for children's play and protection. Its rubber mulch is made from closed-cell sponge rubber. 

Closed-cell sponge rubber stands out with its unique cellular structure, featuring closed, non-interconnecting cells. This distinctive design sets it apart from other rubber materials. Here's why:  

1. Doesn't absorb water. 

The cells are sealed off from each other, preventing the passage of air, water, and other fluids. It is resistant to mold and mildew, which can degrade other materials. 

 2. Resilient and durable. 

Closed-cell sponge rubber offers a unique combination of resilience and durability. Its closed-cell structure ensures it maintains its original shape and performance over time, even under pressure, providing long-lasting play surfacing. 

3. Best in fall protection. 

It has cushioning and shock-absorbing properties. Closed-cell sponge rubber compresses under pressure to absorb the energy from a fall's impact. It then rebounds and returns to its original shape, ready to absorb the next impact. Proof of this is the ASTM safety test results for Rainbow Mulch. Rainbow Mulch at a 3" depth over compacted soil exceeds a 20' critical fall height, offering the best fall protection. 

4. Performs in the elements. 

Closed-cell sponge rubber maintains its properties over a wide range of temperatures. It can withstand high temperatures without losing its flexibility. It is resistant to chemicals, oils, and solvents and performs well in harsh environments. 

5. It's clean and safe. 

Close-cell sponge rubber is manufactured using safer materials and processes. Recycled tire rubber may contain additives, chemicals, and metals that could pose a risk to children and the environment. Rainbow Mulch starts with hand-picked raw materials to create a closed-cell sponge rubber that is California Proposition 65 compliant. 


Overall, closed-cell sponge rubber provides a reliable and effective means of protecting against falls. It is durable and performs well in the elements, making it the best playground surface material. Parents and schools don't have to worry about the risk of wires, toxins, or dirty clothes and shoes. For those seeking the best performance and fall protection, please explore rainbowmulch.com.