Actually, they are all made of stach, not PVA...edible also if you get hungry.
Have a look onto the auction sites...'biodegradable void filler'
All companies sell pretty much the same stuff, fox, solar, gardner etc. I bought 15cubic feet for about £20 including postage. Enough to last me a live time!! I have actually re-sold the stuff on there as nuggetts for fishing. I made ~£150 profit for half of the bag, selling in lots of 100!! I got bored of doing it tho, so gave up!
I still have tonnes left over in my garage. Always good to have a decent supply to fill up my container before I go.
I did a few tests in the bath with coated braid, and most of the time it did kick the bait away. Not perfect, but then again, when a fish moves over the bottom, it would naturally waft the debris and your hook bait around. So you can never be sure that your rig is lying in a good position all the time once the fish move in. How can you be sure that fish don't take baits lying on top of your lead?? When feeding, carp dont pick up food off the bottom with their lips, they suck it in, so would they even feel the lead, unless they where tight to the bottom???