Compost bin 'duvet'

[StephenOak]

Fill heavy duty black rubble sacks with rockwool, then fold over the open ends, and superglue / gorilla glue / frame sealant seal the end.

I really don't want to sound snarky but have you read this thread? What you describe is essentially what I am doing. What I asked for was something to seal the plastic, that is something specific (e.g. 'I used XYZ tape when I ...'). You have just said 'use a good glue'.

But two one of your examples will almost certainly not work as most plastic bags are made of PE.
<quote>
Will Gorilla Glue bond plastic/vinyl/rubber?

Gorilla Glue will work well on many types of plastic; however, we do not recommend for use on polypropylene (PP) or polyethylene (PE) plastics or any type of rubber with high oil or plasticizer content.
</quote>

<quote>
Will Gorilla Super Glue bond plastic/vinyl/rubber?

Gorilla Super Glue has been engineered to achieve excellent results on difficult to bond substrates. It is formulated to bond a wide range of similar and dissimilar materials including most plastics, metals, elastomers, wood, and porous surfaces. Gorilla Super Glue requires some absorbed moisture on the bonding surfaces to cure. Certain difficult to bond plastics, such as polyethylene and polypropylene, have little to no moisture and will not form good bonds.
</quote>

 

[Brigadier]

OK......

Fold the end over, clamp between two lengths of timber (treated tile batten?), and screw through both?
Clamping the end shut?

 

[lostinthelight]

This type of thing is good stuff:
https://www.firsttunnels.co.uk/spar...MI46rT2Y-Q3QIVxrTtCh1-fgHaEAQYASABEgLr1vD_BwE

 

[StephenOak]

This type of thing is good stuff:

Thanks, that looks promising.