Are compostable bags really compostable? Part 4

Part 4 of an experiment in home composting.

I am conducting an experiment to see whether The Guardian’s compostable bags do actually degrade in a home compost heap.

I checked up on the heap again on Sunday 1 September, four weeks after the last check and eighteen weeks after I started the experiment. Again, I removed all the material carefully with a spade and trowel, placing it all into a large bin.

The first item I came across was the Happy Pear compostable pouch which I placed in the heap just four weeks before. It hadn’t decomposed much – if at all – as you can see from the picture below:

I didn’t expect to find much progress on this, certainly not after four weeks. The label says it is designed for industrial composting, so I’m not very optimistic that it will breakdown in a domestic situation. But we shall see.

Further down was the remnants of the compostable cup which I had added in July, at Stage 2 of the experiment. This has now further disintegrated further, so I’m pretty confident that this will vanish completely in due course.

Of the clear film bread wrapper left in the heap at the same time, I now found nothing. I can therefore record that this was composted completely within eight weeks.

Finally, I dug right down to the bottom of the heap to see what was left of the initial two compostable bags. These have been further reduced to a few very small scraps of compostable film:

It’s not now possible to tell from which of the two bags the scraps come, which is good news. It seems to me likely that there won’t be anything discernible by the time I next open up the heap, but we will see.

Finally I have decided to add another item to the heap: a compostable coffee cup made by Down2Earth Materials in Cork. (This firm may well have made the earlier cup which I placed into the heap in July, which you can see above. Unfortunately I didn’t keep a note of the manufacturer which is why I’m adding a new cup at this stage.)

Here’s the cup:

And here it is in the heap:

Once again, I’ve put all the part-composted material back, and topped the heap up with plenty of new kitchen vegetable scraps and garden waste. I will take another look sometime in late October.

Part 1, 28 April 2019. 
Part 2, 7 July 2019.
Part 3, 4 August 2019.

Are compostable bags really compostable? Part 3

Part 3 of an experiment in home composting.

I am conducting an experiment to see whether The Guardian’s compostable bags do actually degrade in a home compost heap.

I checked up on the heap again on Sunday 4 August, four weeks after the last check and fourteen weeks after I started the experiment. Again, I removed the material carefully with a spade and trowel, placing it all into a large bin. A few inches down, I came across the material I had deposited four weeks ago. On the left you can see what it looked like then – a paper cup and a large transparent bag, which had been a bread wrapper.  I was pleasantly surprised to see that there is very little left of the transparent bag – in fact the printed label is the only distinguishable bit remaining. Here is what it looked like:

So hats off to NJB who say they make a compostable film. My experiment would seem to justify this claim. The compostable coffee cup has decomposed less, but it looks as though it is also on the way to breaking up completely.

I carried on removing material in order to reach the bottom of the heap, where the two original compostable bags were placed back in April. Here is what I found:

There is now very little left of either bag. The pieces shown above were the only traces of both, and I therefore have every hope that there will be nothing left to report next time round.

My latest addition to the experiment is a pouch which once contained Happy Pear granola, manufactured by the Israeli company TIPA. The packaging tells you to put this into ‘industrial composting’ (i.e. a brown bin) but as I only use our brown bin very rarely, I decided to see how well it goes in a home compost heap. Here is how I left it:

I’ve now returned all the compost to the heap. I will keep on adding more material on top and we will see what it all looks like again in a month or two.

Are compostable plastic bags really compostable? Part 2

Part 2 of an experiment in home composting.

I am conducting an experiment to see whether The Guardian’s compostable bags do actually degrade in a home compost heap.

I finally got round to checking up on the heap on Sunday 7 July. This was exactly ten weeks after I had begun the experiment. Longer than I meant to leave it, I know, but various things intervened.

I began by removing all the material carefully with a spade and placing it into a bin. As I got near the bottom, I could see that there were two obviously separate large pieces of partly-decomposed plastic, but it wasn’t possible to tell which one was the Guardian bag and which was the one made by Greensax. There were also a number of smaller fragments which could have come from either bag.

I had to move them around a bit to get enough material exposed so that I could take a photograph, but this is roughly where they were when I uncovered them, and these are the biggest pieces I could find.

On checking back their positions in the dump from my earlier picture (left) I reckon that the fragment on the left is the Greensax bag and therefore the one on the right must be the Guardian. I was pleased to see that there were a lot of worms in the heap so they must have been doing a good job. There was no sign of the two wooden plant markers which I had carefully dated, which made me think that in the interests of science I should probably have used plastic markers. No matter.

I must admit that I was pleasantly surprised that so little is left of the two bags after just ten weeks. In my regular composting activities I have been using two or three Greensax bags every week for at least the last two years, and there are many fragments of plastic bag left over in all my bins. I have diligently moved these back to the large bags in which this autumn’s leaves will be kept, when the cycle begins again.

Having returned all the compost to the heap I then added two further distinct items, both of which claim to be compostable.

The first is a ‘compostable’ cup, acquired by my daughter at an event in the AirBNB offices. The second is the clear packaging from a loaf of bread, bought in a local food co-op. This is made by an Irish company, NJB. The company says that this is made from vegetable resources and is completely compostable.

I’ve covered all this with grass cuttings to a depth of an inch or two, then topped it off with more garden waste and vegetable peelings etc from the kitchen. I will carry on adding to this for another four or five weeks and then take a look at what has happened below the surface.

Are compostable plastic bags really compostable? Part 1

Part 1 of an experiment in home composting.

I am conducting an experiment to see whether The Guardian’s compostable bags do actually degrade in a home compost heap.

I have been using compostable plastic bags in my normal composting activities for several years but in order to run this experiment I decided to build a separate new compost bin and start a new pile from scratch. So today I have created a new heap in my brand new bin, using two loads of kitchen compost waste in separate compostable bags. One is from a Saturday edition of The Guardian, the other is from the normal range I buy in my local supermarket, made by the Irish company Greensax. I put both of these into the bin and added in some extra kitchen waste, some in a brown paper compost bag, the rest just a random pile of peelings, teabags, used coffee grounds, apple cores and the like. This is the pile shown in the photograph below, resting on some old slats at the bottom of the bin.

I then added a small amount of other garden waste (some grass cuttings and some specially cut nettles) and topped the whole thing off with a couple of spadefuls of compost from one of the other bins which have already done their work.

Here is what the new bin looked like this afternoon, after I had finished work:

I will keep on adding ordinary garden and kitchen waste to this over the next month, and then turn the heap over how much of the two plastic bags have disintegrated. Watch this space!