If you’ve ever stopped by our warehouse after a big order for plastic films and bags, you might’ve noticed the stack of old, damaged shipments leaning against the back wall next to a few bales of food scraps and yard waste. A few years back, I’d have told you that plastic is plastic—once it’s done its job, it’s only good for a landfill or the recycling bin that’ll send it halfway across the country to sit in a pile for 400 years. But as a supplier of these very products, I’ve spent the last few years listening to customers, testing new materials, and asking the kind of questions that’ll make your average logistics manager roll their eyes: “What if this stuff actually breaks down, not just breaks into smaller pieces?” Plastic Films and Bags
I’m not a scientist, and I don’t have a PhD in polymer chemistry (though I’ve sat through enough webinars to know a plastic additive from a compostable resin when I see one). But I’m the guy who fields calls from grocery store managers worried about their produce bags turning into microplastics in community compost bins, and from packaging designers testing films that might work for a delivery but not a landfill. Today, I want to talk about something that’s confused a lot of people—especially small business owners and home gardeners—for years: What are the real conditions that make a plastic film or bag compostable, not just “compostable” on a label?
First, let’s get one thing straight: Not all plastics are made the same. Most of the plastic films and bags we sell (the ones for shipping, food storage, retail checkout, and agricultural use) are made of conventional polyethylene (PE)—a polymer of ethylene molecules linked together in long, tight chains that nature can’t pull apart easily. That’s why a regular grocery plastic bag will still look like a bag 10 years after you toss it in a backyard pile. But the new products we’ve started bringing in (and yes, we test them ourselves before we stock them) are different. They have additives, or they’re made from biopolymers like PLA or PHA, that let microbes eat them— but only under specific conditions that most people don’t realize.
Let’s start with the basics of composting, because if you don’t know how a compost pile works, you can’t understand what a plastic needs to break down. Composting isn’t just “stuff rotting outside.” Industrial compost facilities (the only places that can actually break down most compostable plastics) are controlled environments. They’re not your backyard bin that you turn once a week. A properly run industrial compost has three non-negotiables: temperature, moisture, and oxygen. I’ve had a compost expert from one of our local facilities explain this to me so many times I can recite it in my sleep. The ideal compost temperature is 130°F to 170°F. That’s hot enough to kill weed seeds and pathogens, but more importantly, it’s the sweet spot where the mesophilic and thermophilic microbes that eat organic matter (and the right kind of plastic) thrive.
Moisture is next. If your compost pile is as dry as a desert, microbes go dormant. If it’s as soggy as a swamp, there’s no oxygen, and microbes turn anaerobic, producing smelly gasses and not breaking down much of anything. The ideal moisture level is about 50-60%—think a wrung-out sponge, not a puddle. Then there’s oxygen. That’s why industrial composters turn their piles every few days, or use forced air systems, to keep air flowing. Without oxygen, you might get some breakdown, but it’s slow, and you won’t get the kind of complete decomposition that makes a material truly compostable.
Here’s where most marketing lies. A lot of bags on store shelves say “compostable,” but what they mean is “compostable in industrial facilities.” Very few of them meet the standards for backyard composting, and even fewer work if you just toss them in a forest or a ditch. For example, PLA—polylactic acid, made from cornstarch—will technically break down in a backyard bin, but only if your backyard bin stays above 120°F for weeks at a time. Most backyard compost piles peak at 90-100°F in the summer and drop lower in the winter. So that “backyard compostable” bag you bought? It’ll probably just sit there for years, breaking into tiny microplastics instead of being eaten by microbes.
Then there’s the additive-based plastics, sometimes called “oxo-biodegradable” or “degradable.” These are different from biopolymers because they’re still made from petroleum, but they have a chemical additive that weakens the plastic chains when exposed to UV light and oxygen. But here’s the catch with these: They don’t break down into compost—they break into microplastics. The ASTM International standard for these isn’t even labeled “compostable”; it’s “bio-degradable in ambient environments.” So if you see a bag labeled “oxo-biodegradable,” don’t toss it in a compost bin. It’ll leave tiny plastic particles that contaminate the finished compost and end up in your garden, your vegetables, and the water supply. As a supplier, I make sure to clearly label which of our films and bags meet which standards, because I don’t want customers wasting their time or harming their gardens.
Another big condition: time. Compostable plastics aren’t instant. Most standard-compliant films take 80 to 180 days to break down completely in an industrial compost facility. That’s not fast, but it’s way better than 400 years for conventional PE. I’ve seen tests from a compost facility where they buried a sample of our certified compostable produce bag and dug it up 90 days later—there was nothing left, just a fine, nutrient-rich powder. But if you take that same bag and leave it in a park, even in the sun, it’ll still look like a bag six months later. The UV light will make it brittle, but it won’t fully break down without the heat and microbes from an industrial pile.
Wait, what about home composting? A lot of customers ask us about this, especially small-scale gardeners and apartment dwellers. Are there any films or bags that work there? Yes, but you have to look for specific certifications. The BPI (Biodegradable Products Institute) certification for home compostable is strict, and only a handful of products meet it. But even then, you can’t just toss them in a regular pile. You have to have a hot compost bin that’s built to hold heat, or keep the bin in a sunny spot and turn it frequently to maintain that 130°F minimum. I know a customer who runs a small community garden in Chicago—she started using our home-compostable seedling bags, but she had to adjust her pile by adding more green matter (grass clippings, food scraps) to get the temperature up. It worked, but it’s not set-it-and-forget-it. A lot of people think compostable is a magic solution, but it still takes work.
There’s also contamination, which is a huge issue. Even if you have all the right conditions, if you toss a conventional plastic bag into a compost bin with compostable films, it’ll contaminate the batch. The compost facility has to sort out the non-compostable materials, and if there’s too much, the entire batch has to be sent to a landfill. I’ve talked to a manager at a Midwest industrial compost facility who told me that contamination from mislabeled bags and regular plastics is so bad that they have to reject 10-15% of the material they receive. So as a supplier, I make sure to educate every customer—small business, homeowner, or other supplier—about labeling and sorting. If you use our compostable films, make sure they’re not mixed with regular plastic. That’s not just my advice; it’s the compost facility’s, and it’s the only way this whole system works.
Let’s talk about what happens if the conditions aren’t met, because that’s the part no one talks about enough. If you toss a compostable bag in a backyard bin that’s too cold, too dry, or doesn’t have enough oxygen, it’ll break into microplastics. Those tiny particles don’t go away—they stay in the soil, get eaten by worms and insects, and eventually make their way up the food chain. That’s a problem, because even though they’re made from natural materials like corn, the processing and additives might leave behind traces of chemicals that aren’t good for the environment. Conventional plastics do the same thing, but for way longer. So it’s not a “zero impact” solution, but it’s a step in the right direction—if you use it correctly.
I’ve spent a lot of time testing our products, both in labs and in real-world conditions, because I don’t want to sell something that sounds good on paper but doesn’t work for the people who use it. Last year, we partnered with a local agricultural supply co-op to test our compostable mulch film on a 5-acre corn field. The mulch is supposed to break down after the growing season, so farmers don’t have to remove it. We monitored the pile at the local industrial compost facility, and the film was fully decomposed in 110 days, which is right on the ASTM standard. But a few farmers tried leaving it in their fields over the winter, and it didn’t break down at all—because the temperature never got above 50°F for more than a few weeks. That’s when I realized how important it is to be transparent about the conditions, not just the certification. As a supplier, my job isn’t just to sell a product—it’s to tell people exactly how to use it, what it does, and what it doesn’t do.
So to wrap this up, if you’re considering switching to compostable plastic films or bags, here are the non-negotiable conditions you need to know: First, the product has to be certified to a specific standard (ASTM D6400 for industrial compost, ASTM D6868 for home compost—don’t just trust a “compostable” sticker). Second, it needs to be in an industrial compost facility that maintains 130°F-170°F temperature, 50-60% moisture, and consistent oxygen flow for 80-180 days. Third, you have to separate it from conventional plastics and other non-compostable materials to avoid contaminating the batch. Fourth, if you’re using it in a home compost, you need to build or maintain a hot pile that can hit that minimum temperature, and don’t expect it to break down quickly in cold weather or outside.
I know this sounds complicated, and a lot of people wish it was simpler. But that’s the reality of this space—there’s no silver bullet for plastic waste, only better choices, and correct use of those choices. At the end of the day, the products we supply are tools. They’re not perfect, but they’re part of a solution that reduces the amount of plastic sitting in landfills for centuries. If you’re a business owner looking to switch your packaging, or a farmer testing mulch films, or just someone who wants to use products that can decompose properly, I’m here to help. We’ve got a range of certified compostable films and bags, and I can walk you through what works for your needs, how to use it correctly, and what to expect. Reach out, and let’s talk about making better choices together.
Gloves References:
ASTM International. Standard Specification for Compostable Plastics (D6400). ASTM International, 2023.
Biodegradable Products Institute. Home Compostable Product Guidelines. BPI, 2022.
US Environmental Protection Agency. Composting Basics: Industrial Composting. EPA, 2021.
National Composting Council. Compostable Plastics Guide. NCC, 2020.
CHARMPEAK SDN. BHD.
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