When shopping for sponges, choose compostable products that are made of 100% cellulose or other plant-based materials, like loofah. At the end of their life, be sure to compost them correctly. Avoid plastic sponges, which can contain a host of nasty chemicals and break down into microplastics. 

Materials

Plastic

Plastic sponges are our least favorite sponge option. They are made out of plastic (which is derived from crude oil), and getting the foam into sponge-shape requires hydrocarbons (which are set to be phased out by 2030 because they contribute to ozone depletion). Some plastic sponges are made out of a plastic called melamine that is “thermoset” and can’t be melted down, rendering them unrecyclable. But, even if a sponge is made out of a recyclable plastic, any presence of food scraps or organic material will render it unrecyclable. 

When plastic sponges are inevitably sent to the landfill or end up in the ocean, they can emit formaldehyde and carcinogenic dioxins as they break down, or turn into pesky and harmful microplastics. 

Recycled Plastic

Recycled plastic is always better than virgin plastic, but there are better options out there; these sponges will still contribute to landfill waste or break down into microplastics in the ocean once they’re done scrubbing. 

Cellulose

Cellulose is a material made from biodegradable wood fiber and is an effective, inexpensive option for sponge-making. If you have a home or community compost system, you can even cut your cellulose sponges into small pieces and throw them in the mix (as long as they’re not drenched in fats or oils). If you don’t, you can throw them into the trash knowing that they will not contribute to plastic landfill or ocean waste. The only catch is that when cellulose sponges biodegrade in landfills, the lack of oxygen in the landfill environments causes them to emit methane (a super-potent greenhouse gas) as they break down. The benefits outweigh the drawbacks here, but it’s good to understand the full story. 

If you are buying cellulose sponges, make sure they don’t contain any plastic pieces or polyester filling. If they’re not 100% cellulose, they won’t be biodegradable or compostable, no matter how hard they try. Try to avoid buying cellulose sponges that are bleached or colored. That bright white or pink sponge probably has some nasty chemicals in it even if it’s made of cellulose. 

Loofahs

If you’re able to spend a bit more on sponges, loofahs are the way to go. A few of us here at Finch have put them through the wringer and find them to be super effective. In case you’re thinking about the loofah in your shower, we mean this not this. The great thing about them is that they are literally just slices of a dried-out plant. No sus production process, no nasty bleaches and chemicals. If you live in the right climate, you can even grow them. When they’re worn down, just throw them in your home or community compost bin as long as they’re not drenched in fats or oils. But, the same story applies about methane being released if they end up in landfill.

Sea Sponges

Sea sponges have been used for a very long time (like, the Ancient Greeks and Romans used them). They’re very soft, luxurious, absorbent, and as you might guess, expensive. Some people assume that because of the price tag, they’re also “sustainable”...but, not so much. In fact, sea sponges are in danger of being over-harvested and scientists are pretty worried about it. Sea sponges are a primary food source for a type of endangered sea turtle and since they’re already threatened by sewage discharge and commercial trawling (whereby fishing vessels drag heavy nets across the seafloor, snatching up anything and everything in their path), harvesting them for use in our bathtubs just seems unnecessary. 

Fun Fact

Sponges contribute to about 36 million tons of plastic trash annually.