>vanishes in 13 weeks

Well then it's not plastic is it? Plastic's defining characteristic is that it is not decomposable

The defining characteristic of plastic would seem to be the definition of the word from which they are named. That is, that plastics are plastic. It means they are easily shaped, molded, formed, or extruded.

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ssl-3 5 hours ago | parent | prev | next [-]

That's what they told me in school, too.

But then I got out in the real world, and noticed plastics just falling apart all around -- including stuff that is not intended to fail and which is otherwise still within its useful life.

Like: One year, I bought some used pickle buckets from a local burger joint to use as planters. Within 6 months, they were falling apart: It was easy to break them apart in chunks with my bare hands.

Or the plastics used for cars: They often eventually turn brittle and fall apart, whether interior or exterior. Plastic lenses on USDM cars turn foggy and useless; some types of wire insulation disintegrate. (If we want to talk about environmental cost, can we also talk about the impact of building a new car?)

In some areas, we once used polybutylene water pipes. These tended to fail and damage homes. There was even a billion-dollar lawsuit about it in the 1990s. It was not good.

Meanwhile, a red Solo cup or a plastic drinking straw, once landfilled, will be there a very long time -- but eventually, they will also decompose.

And the UHMW cutting boards I use in my kitchen will probably outlive my grandchildren's grandchildren before they start falling apart on their own accord.

Plastic isn't always forever, even though some people seem fond of saying that it is. Plastic isn't necessarily cheap, either, even though "cheap plastic" is a common expression -- some plastics are very expensive and resoundingly durable (and there's only partial overlap of these two qualities on a Venn diagram).

The truth is somewhere in the middle, but is rather nuanced and variable and difficult to pin down in absolutes.

But plastic (as a noun) does, broadly speaking, have the material property of being plastic (as an adjective).

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throwway120385 4 hours ago | parent | next [-]

You have to put UV and temperature stabilizers in plastics to prevent them from breaking down outside. The sun is merciless and destroys everything in time.

Your buckets would have lasted longer if you had painted them with outdoor housepaint or outdoor water- or oil-based urethane, because those coatings contain uv stabilizers.

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542354234235 5 hours ago | parent | prev | next [-]

>Plastic isn't always forever

But molecularly, plastic is around forever. A wooden bucket will eventually breakdown to not be wood at all anymore. Products made from plastic is not what lasts forever, the plastic itself is.

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ssl-3 5 hours ago | parent [-]

That doesn't sound right to me, either. Let's use PLA as an example of a thing that is definitely plastic.

In the right conditions (hot aerobic compost, which is admittedly difficult to achieve), PLA rather quickly decomposes all the way back down to lactic acid.

Lactic acid is definitely not plastic. It's liquid, and is one of the primary products of the happy little microbes that I nurture in my pepper ferments at home.

Again, it's hard to pin the long-term properties of plastic (noun) down in absolutes.

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TZubiri 4 hours ago | parent [-]

Do you need to grind the plastic into dust for that to happen?

	▲	ssl-3 3 hours ago \| parent [-]
		No, AFAICT. Everything goes faster in hot compost with additional preprocessing, but it's not strictly necessary to reduce things to dust. Hydrolysis of the PLA still happens whether it is dust or something larger. After that, the chains are small enough to be available for microbes to eat fairly quickly. They're just eating one bite at a time; they don't know that they have an entire elephant to eat. More surface area improves immediate availability and speed, but less surface area doesn't cause the process to cease.

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TZubiri 4 hours ago | parent | prev [-]

I meant decomposable by bacteria.

It's trivial to make plastics that break, but then you have many microplastics which again don't decompose.

The breakage isn't even infinite, as the particles grow smaller, the shear resistance grows and it stops splitting, and again nothing decomposes it further

So decompose =/= break.

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bluGill 6 hours ago | parent | prev | next [-]

There are a lot of plastics that are disposable. The first plastics over 100 years ago were made from milk (I suspect the Romans knew the process - it wasn't industrially useful though). Many decomposable plastics have been made over the year. The PLA commonly used in 3d printers is decomposable (in the right environment).

Oil based plastics are generally a lot cheaper than the above though, and they are typically not decomposable. Depending on your use this can be good or bad (I don't want my plastic plumbing pipes to decompose, but other plastics are used up and I want them to decompose)

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BigTTYGothGF 6 hours ago | parent | prev | next [-]

> Plastic's defining characteristic is that it is not decomposable

Behold, a plastic! holds up a rock

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ahhhhnoooo 6 hours ago | parent | prev [-]

What? Plastic's defining characteristic is plasticity -- how moldable, shapeable, extrudeable, pressable, etc it is.

Also, one of the most widely used plastics is PLA, polylactic acid. Which is made from lactic acid from sugarcane, beets, or cassava, and is biodegradable.