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> Decomposable plastics are not new and they’re perfectly usable for “throwaway” containers. I’ve always wondered why they’re not more commonly used in these ca

> Decomposable plastics are not new and they’re perfectly usable for “throwaway” containers. I’ve always wondered why they’re not more commonly used in these cases. There are basically two types of "compostable" [1] plastic. One type uses an additive which allegedly breaks down the long polymer chains into smaller pieces which are then degradable. These come under a few titles, but generally called oxo-degradable. Most scientific consensus is these are nasty and just result in micro-plastic fragments being left behind. The second is PLA, derived from corn starch. This can look like regular plastic but has a lot of limitations, mainly around the usable temperature range and isn’t suitable for any warm/hot use. There are derivations such as C-PLA which can be used for cutlery and some other limited uses, it still doesn’t perform that well with heat though. Both of these also have challenges for their end-of-life processing. They both look like regular plastic and are very hard / impossible to sort from regular plastic which means it’s very hard to avoid contamination both ways. If some regular plastic gets into the composting stream then the whole batch of compost is contaminated and will need to destroyed. Likewise, degradable plastic contamination will destroy a recycling batch. It’s horrendously complex and involves the whole product lifecycle. [1] Note I’ve used the term loosely as it’s a lot more complicated than that as compostable doesn’t mean what the man ins the street generally thinks it does.

52-6F-62 8y ago
That definitely helps my understanding. I hadn't considered the complexities introduced in the recycling stages. People are bad enough at contaminating the recycling bins as is, unfortunately (including myself if I'm careless). Are there really only two types? Where does cellulose fall with regard to those? I've definitely seen cellulose food containers. None of them were ever meant for heating food—only for sealing/containing it for extended shelf-life. This includes bagging, not just hard containers.
- Steve44 8y ago
  AFAIK cellulose, for food packaging, is only available as a clear film and not as a firm rigid plastic. I also don’t think cellulose can be recycled so the end of life is either landfill or composting. It’s also not as functional as OPP films, that is what most of the thin clear sealed plastic packs are made from and also the windows in some packaging. This is being addressed though with products such as Natureflex film which has a cellulose core and moisture barrier coatings on both sides. These barrier coatings themselves are a form of PVC which although not compostable is in an amount which allows the film to pass current certification for composting. This does have a limitation though as it affects the bags ability to be perforated, which many of the OPP bags are. Natureflex is also, currently, a lot more expensive than OPP so where so much is price driven there isn’t the willingness to do this. There is a lot of product development going on in packaging and as with most industries quite a few seemingly great ideas are not practical on a large scale.
  - 52-6F-62 8y ago
    Great info! Thanks. Seems like an interesting problem space. Way out of my field, but interesting regardless. I hope there are breakthroughs, including in cost. From a naive standpoint it just seems to make so much more sense to use compostable (esp. easily compostable) organic-based materials to contain...organics.
otakucode 8y ago
Great information, thanks for it! What do you mean about the compost being 'contaminated' though? Is that due to a breakdown product of the plastic, or are you speaking on an industrial scale where the compost is going to be used for something which can't contain any plastic for some reason? I'm just thinking if I had a compost bin at my house and one plastic spoon got into it, I would expect the compost to still be usable and I'd probably just pick it out when going to use the compost as fertilizer.
- Steve44 8y ago
  In your compost heap a plastic fork isn’t going to make much difference. In commercial composting, where it is sold on to farmers etc., I’m fairly sure there will be a specification as it’ll need to run through their spraying systems and a plastic fork or piece of bag/film could inhibit that. There is also the issue of partially degraded micro-plastics which are then spread across the field and potentially getting into the food chain.
jdeibele 8y ago
Thanks for the detailed answer. I've seen white, clear, and black "plastic" utensils. Most were plastic from petroleum, some from corn. Seems like it would be nice if C-PLA utensils were to be dyed green so it could be separated from the rest.
- Steve44 8y ago
  Interesting idea but there is no way you could get worldwide manufacturing to have a fixed colour scheme for products. Having said that, never say never…..

52-6F-62 8y ago

That definitely helps my understanding. I hadn't considered the complexities introduced in the recycling stages. People are bad enough at contaminating the recycling bins as is, unfortunately (including myself if I'm careless). Are there really only two types? Where does cellulose fall with regard to those? I've definitely seen cellulose food containers. None of them were ever meant for heating food—only for sealing/containing it for extended shelf-life. This includes bagging, not just hard containers.

Steve44 8y ago
AFAIK cellulose, for food packaging, is only available as a clear film and not as a firm rigid plastic. I also don’t think cellulose can be recycled so the end of life is either landfill or composting. It’s also not as functional as OPP films, that is what most of the thin clear sealed plastic packs are made from and also the windows in some packaging. This is being addressed though with products such as Natureflex film which has a cellulose core and moisture barrier coatings on both sides. These barrier coatings themselves are a form of PVC which although not compostable is in an amount which allows the film to pass current certification for composting. This does have a limitation though as it affects the bags ability to be perforated, which many of the OPP bags are. Natureflex is also, currently, a lot more expensive than OPP so where so much is price driven there isn’t the willingness to do this. There is a lot of product development going on in packaging and as with most industries quite a few seemingly great ideas are not practical on a large scale.
- 52-6F-62 8y ago
  Great info! Thanks. Seems like an interesting problem space. Way out of my field, but interesting regardless. I hope there are breakthroughs, including in cost. From a naive standpoint it just seems to make so much more sense to use compostable (esp. easily compostable) organic-based materials to contain...organics.

otakucode 8y ago

Great information, thanks for it! What do you mean about the compost being 'contaminated' though? Is that due to a breakdown product of the plastic, or are you speaking on an industrial scale where the compost is going to be used for something which can't contain any plastic for some reason? I'm just thinking if I had a compost bin at my house and one plastic spoon got into it, I would expect the compost to still be usable and I'd probably just pick it out when going to use the compost as fertilizer.

Steve44 8y ago
In your compost heap a plastic fork isn’t going to make much difference. In commercial composting, where it is sold on to farmers etc., I’m fairly sure there will be a specification as it’ll need to run through their spraying systems and a plastic fork or piece of bag/film could inhibit that. There is also the issue of partially degraded micro-plastics which are then spread across the field and potentially getting into the food chain.

jdeibele 8y ago

Thanks for the detailed answer. I've seen white, clear, and black "plastic" utensils. Most were plastic from petroleum, some from corn. Seems like it would be nice if C-PLA utensils were to be dyed green so it could be separated from the rest.

Steve44 8y ago
Interesting idea but there is no way you could get worldwide manufacturing to have a fixed colour scheme for products. Having said that, never say never…..