Janet Baraclough wrote:
[...]
The other week North Ayrshire council donated every household
who
wanted, a set of dalek compost bins, a smaller perforated compost
tidy for the kitchen, and, what surprised me, a roll of plastic
liners for the kitchen holder. They are like rather flimsy
supermarket plastic carriers, and printed all over "biodegradeable
and
compostable"..confirmed in the instruction pack. (Our co-op
supermarket bags are also biodegradeable plastic, but I know from
verious uses round the garden it must be a slow proces :-).

I'm going to bury a couple of the new compost bags in my old
compost heap and the garden, to see what happens to them. I really
can't think that veg material tied inside them has a good chamce of
decomposing at normal rates.

Janet



I'd ve very interested to know what they're made of

Not my field, but these "bioplastics" are based on biological
polymers such as cellulose and starch instead of the synthetic
"mineral" long-chain molecules. So they will break down by composting
processes, but I have no idea of the speeds.

My only experience is with cellophane, made, of course, from
cellulose (cf rayon): that does seem to compost about as well as
paper. Since the bag material must be stronger and I suppose more
moisture-resistant than cellophane, though essentially similar, I'd
assume it would take longer.

I'd also hazard a guess that the plasticizers may have been chosen to
evaporate quicker than the usual ones; but that's taking me even
further out of my depth. (Where's Franz when we need him? I've
emailed, but received no reply.)

--
Mike.