clairdo2, what have you tried to make, and what were the results? Do you think perlite gave you problems? Perlite is supposed to make your "creation" whatever that is, lighter in weight. Some have tried to substitute vermiculite for perlite. It is also good, and I have some small bowls made with vermiculite in the 'tufa mix. It made the bowl light/weight but gave it a different texture and color than perlite would have. Tell us more about what your problems were.

Hi Clairdo2, What BB says is very true. I've been using just vermiculite and sand in some projects (no peat, so I guess it's technicaly not hypertufa) this summer and they are turning out fine. I even took the step of pulverizing the vermiculite to a very fine (wear a mask as the dust is dangerous) size, small enough to pass through a window screen.

My mix has been 1:1:2, portland, sand, vermiculite. What I've found is you have to be patient with this mix as it cures slower than a regular mix. This has given me a very lightweight product with no large grains of anything showing up.

Are you giving your projects enough time to cure to take demolding or handling? The more info you give will allow folks to help you more too. Don't give up, this is fun stuff.

I have been using portland, peat and vermiculite. It has crumbled everytimeI was just. I'm trying to make a chinese lantern. I have two parts made that seem hard enough but had to start over many times. Was just wondering if I could make it without the vermiculite because of the cost of it.

Can't get vermiculite in large bags here and a small one doesn't go very far.

Certainly. You could make the chinese lantern from just a concrete mix if you wanted. You would not call that 'tufa, but you can make one with peat or perlite. It would be smoother that a 'tufa one, but it would be stronger, too. I would probably mix 1 part portland cement with 3 parts sand. (or even 4 parts of sand) Just a thought, maybe your cement has absorbed moisture and this can cause it not to set up right? Is the portland lumpy ? Do a test casting leaving out the perlite, and use the recipe I just stated and see if that sets up after 24 hours or more. It just may be the portland.

Hi Claire
Phone a place that builds swimming pools and ask where they buy Poolpad. This is a very fine vermiculite sold in big bags (3 cubic feet) and it is very inexpensive. Cheaper than sand.
Are you using fresh Portland cement in your recipe?
One measure of Portland for 3 measures of everything else should give you a strong mix.

The only times I have had crumbly, useless pots is when I think "oh, those lumps in the portland are soft-ish. It'll be fine..." Yes, I've done this not once, but twice. Slow learner. I use 2 portland, 1 sand, 6 vermiculite for my lighter looking pots. I intend to add the unreliable portland slowly to my batches, maybe one scoop per cement mixer load.
Blooming

Sounds like your cement has upped and died :o)

I'm doing preliminary tests at the moment, trying to figure out workable mixes, how to cast hollow (without having to join two halves later), surface treatments etc. etc. etc..

So in the experimental stages I'm buying very small bags of cement, sand and vermiculite. You can run a lot of tests with a 5 kilo bag of cement!

When working with unfamiliar materials - particularly ones you're having problems with - work in tiny batches. I have an old cat-litter tray (nice and flat, with low sides) and I do all my mixing in that, manually (in rubber gloves and mask, obviously).

An easy test is to...
1. Prepare a plastic basin by lining it with cling-film. Use plenty of cling film, overlap it well, and drape out over the sides with plenty of spare.
2. Mix all your measured dry ingredients (cement, sand, peat, vermiculite - whatever you're using) in the cat-litter tray, wearing the rubber gloves. When it's well mixed, make a well in the centre and put in some water. At that stage I start working with a small garden trowel instead of my hands. Draw in the mix from around the water, mix the water well through, then keep on sprinkling in water until you get a good workable paste that will stick together when squeezed.
3. Press the mixture down into the lined basin, making a shell of an inch or so thick. Keep pressing the mixture together, you don't want it loosely packed. Come up a couple of inches up the sides of the bowl.
4. Cover the bowl with a plastic bag (or place inside a black plastic rubbish sack) and leave for 24 hours.
5. After 24 hours lift it out of the basin carefully, using the cling-film to do the lifting. At that stage you can try brushing the surface with a steel brush, cutting it, or try different surface treatments.
6. When you've finished working on it, replace in the rubbish sack, or cover with plastic, for another few days so that it can harden up properly.

Hope this doesn't sound too long-winded - just a run-down on how I work with any new material, to avoid costly mistakes.