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My mixture fell apart? Why?

13 years ago

I used the 2 parts portland cement to 3 parts perlite & 3 parts peat moss. I put it in my molds & wrapped in plastic. 2 days later when I went to dump it out (per instructions), it crumbled into a pile. What did I do wrong?

Comments (6)

  • 13 years ago
    last modified: 9 years ago

    Whose instructions are you following? Was it portland cement or concrete or some other cement mix? Was it horticulture grade (small pieces) perlite? Did you crumble up or sift the peat moss? Did you mix all the dry ingredients together until they were one consistent color before adding water? Did you use water? Was the mixture too wet or crumbley when you put it in the molds? If you give us more details maybe we can help. Billie

  • 13 years ago
    last modified: 9 years ago

    I used Portland Cement & horticulture perlite. I just crumbled the peat moss by hand (didnt sift it). It was already damp so I couldnt sift it. I mixed the perlite & cement 1st then added in the peat moss & mixed together before adding water. I'd watched "Martha Stewart" do the mixture & make it look easy! It was wet enough to form a ball but not dripping. I molded it into vrs containers & they'd said it should pop out in 48 hrs. Then let it air dry for a couple of weeks. When I went to pop it out, it just dumped into a crumbled heap. Was hoping someone would know what I'd done before I try again. Thanks for your help!

  • 13 years ago
    last modified: 9 years ago

    Martha and her staff strike again... :>) The ratio is fine; used it for years. Did you pack it firmly into the molds? Also, "just pop right" can be a rather optimistic prediction. What were your molds made of (plastic, metal, wood?) and what were their shapes? The mixture sticks to metal and wood and if any mold is rigid with straight sides, that trough just ain't comin' out. Also, the mixture after the first couple of days is still fairly fragile, not unlike a pan of freshly baked brownies and doesn't appreciate rough handling getting out of the mold. Especially when one is new at it, it's always easier to line the mold with plastic to avoid having to struggle with the unmolding and increasing the risk of fracturing and breaking that trough.

    Also, with due respect to Martha and her minions, tufa troughs do not "Air dry for a couple of weeks" That Portland (and all cement) needs moisture to cure; pots must be kept damp and there are a number of ways to accomplish this: sealing up in a plastic garbage bag; putting the trough into a tub of water (or pond/lake if you have one handy), putting under a shady bush and spraying with water every day. Do not put troughs sealed up in plasic bags in the sun as the temperature will get way too high and cause the trough to crack. 28 days is a good rule of thumb, but you can get away with less depending on the size, etc.

    Does this help at all?

  • 13 years ago
    last modified: 9 years ago

    The problem is your "dry" ingredients weren't dry. You have to mix the cement, perlite and peat moss at the same time until it's one consistent color. The cement acts as your glue and must coat all the dry ingredients before any moisture is added. Dry out the peat moss.

  • 13 years ago
    last modified: 9 years ago

    Hi! I don't know if I should start my own thread, or post in this one since my problem is related? Please correct me if I should have begun my own.

    Due to circumstances with a neighbor, I need to put my plants in pots (for the time being, at least). I've bought some from the Dollar store, but I need larger. I was looking for an inexpensive way to make or get pots, and learnt about hypertufa. So, my journey has begun :)

    Our hypertufa pots fell apart, also. From reading this thread, I can see where we may have made some errors. But, I also have some questions. I'll share what we did, where some of the errors may have been, and then my questions (if I may :) ).

    A.) Okay, here's what we did (* indicate questions or "responses" to be made later).:

    1. Mixed 3 part perlite*, 3 parts peat moss*, 2 parts portland cement*
    2. We added water*. We did this two ways: 1.) was dryer, but packed in our hands. 2.) the other was moister. The one with more water did hold better, BUT, there were other conditions I've read here that may have been the reason (rather then the water.).
    3. We let them cure for one week before moving. They still seem rather delicate, and pieces come a bit off after one week. The one pot crumbled 1/2 down. But, we had struggled to get it out (we did it the opposite way where we built AROUND a plastic pot, not in it.).
    4. We made three (3) types:
    a. One form was built up on the outside of a plant pot (please read the rest before commenting).
    b. Second was a rock formed in a plastic bag
    c. Third was a free form rock made in a container that had holes in it, with a hold in the center..

    B.) Errors we may have made from what I've read in this thread:

    1. We did not sift the peat moss*
    2. We may not have used the correct perlite?*
    3. We did not mist the posts while waiting for them to cure.
    4. We may not have mixed thoroughly enough. We thought we did, but it is still a possibility that I will certainly need to be more mindful of when trying again!
    5. Not sure of the amount of water* to use.
    6. Wait time? I'm confused on this. We waited one week. More on that, later.
    7. We definitely made the ONE pot too thin at the bottom (the mold was on the inside, and tufa on the outside). It did not slope down. I just didn't build it up, enough. The top looks wonderful! LOL.
    8. The one "rock" we made, we kept in the plastic bag and did not remove it, for a week.
    9. The rock in the container had a puddle of water that was in the center (we'd made a hole in the center of the rock). That one did the best. It was, also, made with a little more water.

    C.) Questions
    1. What does one use to sift the peat moss? What have others, here, have used?
    2. I saw that someone here mentioned horticulture perlite. Now, we did buy perlite for plants, but I'm wondering. The video clip that we saw (I'll post it at the end), showed a perlite that seemed smaller and more powdery. We used Miracle Grows perlite (it was the only one we could find). I've just looked at the bag and noticed that it includes plant food.
    a.) Did I use the wrong one?
    b.) Where is a good source to buy perlite?
    c.) What's the best price? It was the most expensive part of the mix :)
    3. Portland Cement. Someone, somewhere, had asked why an OP poster used it. I'm not the OP here (or on whatever thread it was). However, I got that from two (2) sources:
    This video:
    Gardenweb's FAQs section for making Hypertufa pots:
    4. I know I've read to just add water till I get the correct consistency. Can someine, using the recipe we are currently using, please give me a more specific answer? It should be somewhat consistant (even though there may be some variation. Like when you make dough.).
    5. How long does one need to wait for them to cure? I was very anxious to use them. The video said approximately one week and they are fine to use. Some people say one week, some two, others several. Perhaps it depends on the recipe? Gardening season is short where I am, and I'm anxious to make these and use them :)


  • 2 years ago

    Im had the same problem all 3 of mine just fell apart they seemed more like dirt no like a cement mixture

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