I've been testing a few small pieces by soaking them in water for about 8 to 9 hours. This particular layer can be torn but, even after all that soaking, still offers a strong resistance, as if the fibres are really interlocked. Actually the material came from a pet shop in the form of small squares, used as pet bedding. Someone gave me the waste hay from their Guinea Pigs together with the cardboard.

I always perforate my cardboard before laying, and pick out the plastic remnants some months later. Not just what you describe, but also packaging tape.

I'm with glib. Tape is a pain in the butt to take off a truckload of cardboard, and I don't have much time for sorting anyway. Just make sure the cardboard that goes in can be penetrated by water, tear it up and put it down, then come back later and clean up after the rot has had time to do the grunt work for us.

from my experience all cardboard rots eventually give it some time.....do your best to break it down into little pieces

viper114: It's already in small pieces (see above). The outer layers of corrugated paper is made from Kraft paper, and it would appear that the manufacturing process can incorporate additional strength and water-resistance if required.

I used to put pieces of carboard boxes into a bucket to soak, whereupon they would almost fall apart when torn, but there were some that had a one-sided layer which had the opposite property.

That moisture-resistant stuff is the cardboard used for packing beer, soft drinks, produce and other things that have to withstand moisture and condensation in coolers. There's another category that's resistant to gasoline and solvents in other uses.

It's made with some special soy-based glues and outer coating - a vegetable sourced resin. It will compost, but it's slow. I try to avoid it unless
it's the weed-blocking layer in a path or under shrubbery where it's
resistance is a good thing. I also use them to collect yard trash because if I forget it in the rain it doesn't collapse on me.

To speed it up, shred it .

Sounds like the kind of stuff used in the little cardboard trays for fresh mushrooms. Kind of waxy on the surface but not wax exactly. I've been using them to start my woodstove instead of putting them in the cardboard recycle. I figured they would not do well in the repulping process. Have not tried to compost them.

If it is corrugated, then it isn't the stuff used for beer and soft drinks. I do think it would be very interesting to find out what is different about this than other types.

Martha

I did a search and read up on the construction of corrugated cardboard. The three layers are actually produced completely separately, and brought together at a factory to be combined into the final product. The non-corrugated layers can be as simple or complex as needed to do whatever job is required. They could have printing, painting, or even a wax coating.

The article did discuss the recycling process, and didn't comment on any difficulties with the cardboard itself, yet, just some trouble with gummy adhesives that are sometimes used and pressure sensitive label adhesives. So, I am betting you are running into a source of cardboard that is being manufactured in a less than ideally recyclable manner. Whether it is unsafe or breaking any laws, I can't say. My research was limited to the top article of a Google search. Is there any way you can trace where the pieces of cardboard came from? I wonder if they have resorted to disposing of it via the pet-bedding route because it couldn't be recycled using standard techniques. Interesting.

Martha

Martha: I too looked at manufacturing processes but came out none the wiser. But I have noticed this 'difference' in the non-corrugated layers in other sources of corrugated cardboard. Certain cardboard boxes at first glance seem identical to others until you put a batch of cardboard into soak, then try to tear them up. One layer is fine, but the opposite layer isn't. Because of this, I've always discarded these 'difficult' layers. I wouldn't go as far as to say that they cannot be composted, it's just that I've never tried them. If anyone would like a sample I'll send one in the post to a couple of members, maybe they could offer a better description than mine.

Where the corrugated pet bedding came from will necessitate a chain of enquiries. I'll start the ball rolling and ask what shop it came from to get a supplier name.

OK, it's called 'EcoBed Cardboard Bedding', ( http://tinyurl.com/p4s95xz ) and the suppliers say (edited):

"EcoBed is an easy to use bedding, suitable for chickens, rabbits, guinea pigs. It is made from clean, uncontaminated cardboard. EcoBed is highly absorbent, meaning that the top surface will stay dry and odourless. The corrugated card helps to trap air, and it is virtually dust-free. Ecobed is also pH neutral, reducing the smell of ammonia. After use EcoBed can be put on the compost heap as it is fully biodegradable. This is a cost-effective choice of bedding as there is little wastage."

The bag says 'cardboard shavings', but corrugated board cut up into square is not shavings.

Somehow I don't think it's worth persuing, I can't see any enquiries going to the exact mill that produced the cardboard in the first place, so I'll just have to put some in the heap and see what happens.