Chris Hogg wrote:
Pat wrote:

I did the google thing prior to sending the OP, but couldn't find any
info on whether or not to wet the bentonite before applying to the
lining of the pond.

When bentonite is dug/mined from the ground it's moist and plastic.
For most ponds, it would be used in this condition, with no
intermediate drying, which is probably why you didn't find anything on
using it dry: no-one does.

As to lorry-loads, a local feed supply store sells bentonite by the
#50 sack, thus I was assuming a little goes a long way?

I assume this stuff is dry powder or granules. You would have to wet
it down to a stiff plastic paste, and then trowel/shovel/spread it
onto the pond floor and sides to give a layer at least 2 inches thick
I should think (rather than the 4 to 8 inches suggested in the link I
gave you), given you're on heavy clay anyway. Then you'll have to
tread or ram it down to make sure it's all compacted and sealed. That
is a lot of work. What area is your pond?

Wetting the bentonite will be a difficult job; it's fiendishly sticky
and intractable when wet and plastic. A potential problem with
bentonite lined ponds is that if they dry a bit in the summer, and the
bentonite layer gets exposed, it tends to shrink a lot and it cracks,
meaning you've got to reseal it again to keep it watertight.

But if you're on heavy clay, it would be worth just digging your pond
and filling it with water to see if you actually need bentonite. You
may find that it holds water OK and you don't need it. It would save
you a lot of messy work.

As you may gather, I'm trying to dissuade you from going down the
bentonite route. I've never lined a pond with bentonite, but I do know
a little about what it's like when moist and plastic.


Yes, it's powdered. The pond is not very big, about 12' x 12'. And the
ponds in this area do tend to go dry due to leakage, even with the red
clay base. So I want to seal this one.

I was thinking maybe we could spread a thinnish layer of the powder
over the damp existing clay, and hopefully it would cling even on the
sloped area. Then spray it with a fine mist to wet it and then trowel
it smooth? And then maybe spray it a bit more and then add another
layer, spray it again and trowel it smooth?

I can't imagine why you want to discourage my use of bentonite, since
you won't be the one doing the work (unless of course you'd *like* to
volunteer, you'll be welcome....) unless perhaps you're thinking it
would end up being more costly than buying a rubber liner? My
principle aim is to spend less money whilst still accomplishing the
goal.

Many thanks for your info, by the way.

Anyone else care to chime in?