When to Unmold Large Container

18 years ago

I am very much a novice at hypertufa. My first project was three months ago. I have had success with smaller containers and leaf castings and even making spheres. I needed a large planting container so I decided to use a large round plastic pail 19 inches wide and 16 inches high and placed a smaller round pail on the inside and placed my hypertufa mixture inside between the 2 containers so the walls would be about 2 inches thick. I used a mixture of 2 parts perlite, 2 parts peat, and 1 part portland cement. (In my other smaller projects I used vermiculite but since this container is larger I used perlite thinking it might not be quite as heavy when finished.) I made it 2 days ago and when I went out to check on it today it felt very soft and kind of "squishy". I think it would have fallen apart if I tried to unmold it. Do larger containers take much longer or perhaps its because I used perlite? I live in a very hot dry climate but I did cover it with a plastic tarp. (Sorry for the long post but I'm trying to avoid a disaster!)

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Comments (3)

billie_ann
18 years ago
Iris, It should have been "set" enough to unmold in 24 hours. This is big but not that big.
Regarding your recipe. You should be able to use 5 parts aggregate(perlite, vermiculite, sand,etc) to 1 part cement. I've never gone that high preferring equal parts of all my ingredients except for certain leaf casting recipes. Were all the dry ingredients mixed and blended together? It should be one color (a lovely grey) before adding any liquid. It was portland cement that you used and not a bag of concrete mix? Was the peat moss sifted or at least crumbled and smoothed out and sticks removed? Was the mix very wet that you poured it into your mold? How's the humidity? Did you use water or any arcylic fortifiers? Did you use any dye in the mix? Hope by now that your container has setup enough to unmold. Billie
iris_9
Original Author
18 years ago
Thank you for your help, Billie. My ingredients were all dry and I did my best to blend it all together, but since I made a much larger batch than I usually do and since I waited until almost dark to start my project and didn't have much light I probably didn't mix as well as in past projects. I added water slowly (no fortifiers or dyes) just to the consistency of brownie mix and since it was still pretty hot outside (and dry) I did have to keep adding more water to keep it workable. I also had to make up about about another half batch to finish it (and by then it was dark outside and I'm working by feel only). I did use portland cement not concrete. I didn't sift my peat since it was pretty clean except for a few small twigs which I threw out. I squeezed any lumps. I thought because it felt so "spongy" when I felt of the top of it that maybe it was due to using perlite instead of vermiculite. (?) Anyway I am on my way outside in just a few minutes to attempt to unmold. Wish me luck!
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iris_9
Original Author
18 years ago
I unmolded my container and in doing so about the top third crumbled off. It was still pretty soft, but I wire brushed it to even it out some. It looks pretty rustic but I like the look. It actually will work out all right because its still deep enough to plant a Christmas cactus that is very old and belonged to my mother-in-law before she passed away. It really needs to be re-potted. I put the pot in a large trash bag while it finishes setting up.