dragonfly, I can't imagine using hypertufa for a pond liner. I use the recipe with peat moss and the peat moss degrades over time giving you the lovely nooks and crannies. I've made bird baths and fountains with hypertufa and you work the mix to bring the "cream" to the surface. The "cream" is the finer particles of portland, sand and in this case small amounts of peat moss rise to the surface. Similar to finishing a smooth sidewalk or patio. Some people on this forum line their creations with mortar where the water will wear away the surface or something like a bird bath that you would scrub. Well, maybe you wouldn't scrub your's but I do, lol! Billie

Thanks for the info billie_ann. I can understand why the surface that's in contact with the water would have to be solid (as opposed to porous) to last. But assuming that is done, I'm just curious whether it can hold water without degradation over a relatively long period of time.

Maybe I'll just have to make some 'bowls' and test it out.

Becasue of the ingredients it is not likely to hold water "well" . Some people may skim coat the tufa, with a thin coat of portland. That may work, but why not just use concrete.
Tufa - its purpose is to create a light weight container that can be used for plants that like well drained soil.
mike
Suggest you try and make some
Mine hold water for a little while but eventually the water seeps though.

I made a few small bog gardens from hypertufa bowls and they hold water. You have to work the hypertufa mixture on the inside of the bowl to get a smooth seal. Billie

Hi again billie_ann.

What do you mean by 'work the hypertufa mixture'?

plantman, I understand it's naturally porous, but really
like the way it looks and was just wanting to understand its characteristics better. But you're right, I just need to experiment and play with it first.

Just as I wrote in my first post "work the mix to bring the "cream" to the surface. You're bringing all the fine particles to the surface and it will seal just like a mortar mix lining. Billie

I'm also curious about strength but for different reasons.

I want to know if my hypertufa columns can bear weight. I have a very heavy piece (400 lbs) of pink marble I want to make into a garden table on faux bois or some such concrete sculpting.

Can hypertufa, reinforced with rebar, bear this weight?

Thanks!
Clare

Here i am 13 years later to this thread. has anyone yet perfected creating a water tight small pond with this?

Same here, I want to make a small frog pond by lining old old Belfast sink with tufa.