Poke your finger into the opening. If you can dent it with your fingertip, it's too soon to unmold. If you can't dent it with your fingerNAIL, I would think it's okay to break the mold. Put it in a paper grocery bag and just tap it.

Look before you reach in!

Sue

demaris, I hope you included some cement in your mix too.... otherwise you'll be waiting a longgggg time for it to set up! :)

It has been 28 hours and no sign of setting up! I am so disappointed.

I used a recipe I got right here on Garden web:
1 part pre-mixed sand mix
1 part peat moss
1 part perlite or vermiculite

I used this sand mix to make concrete leaves last fall and again last month - nothing was wrong with it a month ago! Could it deteriorate in a month? It had a few lumps in it the size of a plum, but they crumbled easily.

What if I got too much water in it? I followed the instructions carefully, but as I worked, some water leached out.

Maybe the peat was the wrong kind of peat? Could it spoil the chemical reaction of the cement?

Waaahhh! What did I do wrong? Is there still hope?

Hi demaris
Give them a few days.
That is a pretty weak mix but it should cure quite hard.
If you want speed try 1 portland to 3 everything else with a 10-20% acrylic admix.
This recipe will set quite hard overnight.:)

Well, it's been 48 hours and everything is as crumbly as when I started.

So, I'm running a test with small samples: pure sand mix, sand mix and perlite (1 to 1), and sand mix and peat (1 to 1). We'll see what comes of that.

I don't like the consistency of the perlite mix - very grainy and gritty. The peat mix acts more like concrete. Is this to be expected?

Hi demaris
It depends on how course your perlite is, also your peat.
I like the texture of a peat mix better but fine perlite will make a nice finish especially in colored tufa.
This half ball is 1.5 perlite to 1 part sand but it is very fine perlite.
Like sugar. You can see the white specks of perlite in the pink
{{gwi:66066}}

Just to follow up on this.
That ball is only 16 hours old and about 3/4 inch thick.
I unmolded it and shaped it with a coarse rasp and wire brush to what you see in the picture.
A good recipe can be light, strong and cure fast.
I was impressed because the large portion of cryogenic perlite made the piece very light even though it is wet.

I'm really loving this perlite even thought I seem to have a bad reaction to it's dust.

{{gwi:66067}}

12-hour report:
The sand mix sample is hard.
The perlite/sand mix sample is getting hard.
The peat/sand mix sample is crumbly.

My perlite is sort of mixed - some of it is fine but a good portion of it is like Rice Krispies. I wonder if I can crush it and make it smaller?

I sifted the peat so it is very fine (and dusty!) I'm wondering if it has some chemical additive that is messing up the concrete. It's real old peat we have had hanging around for some years. Would I do better with vermiculite?

I love the red bowl! Can't wait until I get this process right - I even got the nerve to go to a glass shop and get some broken tempered glass for a geode - and there it sits like wet mud. :-( At least I can use the glass globe again when I wash it out! :-)

I love working with vermiculite, it does setup quickly and makes preety strong tufa. I don't like that it acts like a sponge soaking up water. This may not be good is a freeze thaw situation.
I have no idea why your peat would cause problems.
Peat sets well for me and I like the way it finishes.
You could try a bit of admix, that speeds things up and gives a stronger tufa. Either the real stuff (Acrylic)or Elmers contractors glue from HD works great.

The pink bowl is actually half a ball. It is now been joined with the other matching half to make a round pot.

Here is a picture of my first round pot. I sold a rather nice rough peat version to a neighbor.
I was more interested in colors and texture than form but making ballas this way is pretty easy and you can reuse your molds. I have some rather large ones almost 20 inches across started. They could be very interesting to handle once done.:)
{{gwi:71521}}

That striped pot was your FIRST? I am in total awe! Your work is just beautiful!

Are those samples of your colors? How do you add the color to be so intense? Is it those colored tablets?

Where is the seam on the round pot? Between the brown and the yellow, I'm guessing.

Do you have a pic of the round red pot? What balls do you use for molds? I have a basketball and another rubber ball from the TS that I was going to cut open and use for sphere molds. Would they work for round pots?

Questions, questions - I can see I have a long way to go! First, find a mix that hardens. :-)

The striped blue brown was my first round pot.
I just wanted to make something out of a pretty blue.
These are concrete dry pigments.
To get the dark blue you must trick the eye by using black sand or in my case copper slag.
Most of the colors other than the blue are just little amounts of pigment but in white portland not grey.
The yellow and red use hardly any pigment at all.
You can get much richer colors than these by adding more pigments.

The pot is two halves (one brown one blue) formed on an 8 inch glass light globe then 'glued' together with yellow cement.

The pink pot is still in the mold joining the halves. I usually give this a full 24 hours before remove the mold.

I use glass and plastic light fixture balls for this. I have several all the way up to 18 inches in diameter.
I cover them with plastic wrap, slap on the mud, wait about a day and the remove the globe.
I have never tried rubber balls.
I have a seamless ball started right now. It will be interesting how it turns out.

Hi demaris,
I don't think it's the peat moss itself that's causing the problem. It's more likely that 'tufa made with a premix is going to be weaker as TE explained. It would probably be fine if you were using it in a recipe with regular portlands instead of a premix. Something that might be worth trying is dampening your peat first (hot water works faster) not real wet , just enough so it's not dusty...much nicer to work with and maybe the fact that it's sooooo dry is interfering with the hydration process. I do remember reading somewhere that when mixing concrete it was good to use damp sand. Hope you find a good mix soon and can get on to the fun part.

TE, Nice sphere, easy you say ? ...think I might have to try one soon.

Hi PR
I know they say to use damp sand and damp peat but I prefer to use bone dry materials except rock. But I do mist my projects like crazy right after I form them.
I might be compromising strength but my test bricks now several months old are darned strong. I can't even get them to break by freezing them in my freezer.

If you can make half balls on the outside of light fixtures 'gluing them together with a 'mortar' heavy on the admix is easy.
Shaping the mud on the ball can be tricky because it can slump. I use a dry mix and trowel it uphill on the globe until it appears round.
You can always gring off the fat bottom with a rasp to get the halfball round.
I have more half balls in plastic bags around here right now than anything else. For the big ones I'm doing a 1 inch layer of strong perlite concrete first using grey portland. I will then apply my finish coat to that.

For me right now I'm trying to get a strong ball but as light and thin as possible. All this testing takes sooo much time. You need to cure a month before you really know what you have. The recipe I used for the pink ball seems to be good to go. I have 2 month old bricks of the stuff that are very strong and unbelievably light.
What's even better is unlike peat and vermiculite they do not absorb huge amounts of water weight when they get wet.
I like this cryogenic perlite so much I've ordered 10 bags for winter. That is a lot of perlite.:)
Considering it's volume it really isn't much more money than playsand.

I'm sorry but I don't have a finished picture of this. My camera has went into the shop for repair. It stopped zooming.
But here is a picture before joining. You have to imagine a 1 inch wide puffy white section between the two halves.
The color is a lighter pink as well.
It's planted with a pink geranium.
It does look nice..at least to me.
The stand is like the one under my blue ball but is coal black.
You can see the black sample bricks behind the ball.
I'll post a picture of the finished pot once I get my camera back. Unless some one buys it.:)

I know someone was asking about black.
These bricks are pure copper slag so it sparkles like metalic paint in the sun. Very cool.
I have a BIG ball, almost twenty inches started that will have this coal black finish if I don't break it. Handling big balls is a challenge.

{{gwi:71522}}

Tufaenough, your things are just beautiful. You are a real pro and an artist at this. I have a long way to go, but I thank you for your inspiration. Also that I have seen what you do with the glass globes before I filled and broke all of mine!

I bought a bag of portland and a bag of tropical sand, and intend to spend part of my weekend trying 'tufa again.

Thanks for the encouraging words demaris:)

I like to do stuff a little different from everyone else but trust me it's not that hard at all.
Because this ball is mostly soft fine perlite the 'carving' with a rasp is pretty easy and you have several days to do it.
The light perlite also doesn't slump much either so keeping the ball close to round is pretty easy as well.

And using pigments is the easy way to color stuff. Painting takes a lot more skill.