[Cob] RE: Adhesion/bonding of PVC and Cob

[Amanda Peck]

Probably right.  PVC is nowhere near as slick as straight vinyl, it comes 
with numbers and specs stamped on it, you can write on it, and IIRC it 
stains from contact with red clay.  (Art professor in Alabama gave his 
students the challenge of writing on vinyl--gutters or something, nobody 
succeeded in making a permanent mark on it.  From personal experience, 
sharpies and asphalt paint don't work, sharpies just wipe off, paint peels).
......................
James Thompson wrote (snipped)

Ok, I'm going to weigh in on the cob/PVC question...

I don't buy the vacuum theory, for a couple reasons:  there's no change in 
airspace when you pull an open piece of pipe through cob, and also cob is 
not air-tight.  Any vacuum that did occur would be quickly filled with air.

For me, the described example is somewhat analogous to pulling a nail out of 
a piece of wood.  I have two theories on what's going on:

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