Originally published at: https://boingboing.net/2017/11/15/silicone-stretch-lids.html
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Why are these better than normal canning lids?
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Another misleading headline. What I expected:
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I wonder if the environmental impact from manufacturing these and cleaning after use is greater or lesser than other options such as plastic wrap.
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Sigh… Largest one still goes up to just 12" diameter. I’ve been looking for one that’s big enough to cover my bread dough bowl for years* now. Problem is, it’s 17" across.
So, uh, if anyone knows of where I can get one in that size, I’d appreciate a pointer!
The two alternatives I’ve tried have been plastic wrap and aluminium foil, with results being pretty much what you’d expect. Plastic wrap, which doesn’t stick worth a damn to wood, I might add, can be reused reasonably well once or twice after the initial use. However, folding it and putting it away for a while pretty much precludes any subsequent reuse. Aluminium foil is far more reusable, but good luck getting an airtight seal with it the first time, never mind on subsequent uses. I don’t need a perfect airtight seal in this case, so I’ve been able to use the same piece of foil for multiple months. I just store it with the bowl.
So, there’s a huge caveat that it all depends on how – and how long – you’re using each of the alternatives. That said, I tried to answer your actual question.
First, here’s a comparison of plastic wrap vs. aluminium foil. The tl;dr version: if you use both plastic wrap and foil just once, plastic wrap wins by a huge margin on all counts. If you use the foil 3 times – since most people don’t reuse plastic wrap – the two are tied on aquatic toxicity and fossil fuel usage. If you use the piece of foil six times, the two materials will now be tied on GHG emissions and human health impact, and the foil will be ahead on the first two criteria.
A brief note on recycling foil though: It technically can be recycled, but it must be clean of food residue and grease. Do you wash your foil before putting it in the recycling bin? Yeah, me neither. Most recycling processors won’t accept it because the processing cost would spike – and dirty foil can contaminate an entire load of aluminium cans.
Comparing either one with silicone is more of a challenge. There’s a huge variety of products and materials silicone is incorporated into. The closest I could get was this post about silicone cookware. The tl;dr is that silicone breakdown products seem to be better for the environment – it’s essentially sand – and it doesn’t tend to microfragment the way polyethylene does, for instance. It’s also more thermally durable, so it should last longer – though I have some questions about mechanical durability in something like a stretchy lid. All that said, the manufacturing process and specific ingredients are all proprietary, so good luck getting the whole picture.
*on and off, not continuously
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