If you have been making hypertufa for a while, I am sure you have altered the basic hypertufa recipe to some degree for a particular item you are making, for the conditions you’re making it in, and in some instances, altering it based on the ingredients you have at hand.
By definition, hypertufa is an anthropic rock, (that just means a rock made by humans). Mostly anthropic rock is thought of as cement. But those of us who make hypertufa are looking to make something that looks like concrete but is lighter and easier to use as planters or other garden art and ornaments.
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But first of all, what is the Basic Hypertufa Recipe?
The basic recipe uses Portland cement, a fine baby-powder-like or flour-like powder that is gray in color. If yours is chunked full of gravel and sand, that is not the Portland cement (or General Purpose Cement) that you want for hypertufa. Concrete mix is NOT for hypertufa.
The next ingredient is vermiculite or perlite (sand can also be used too). This is a part of the aggregate that goes into hypertufa along with the Portland cement which results in a lighter weight than if you were making CONCRETE. (The concrete is made with Portland cement and gravel/sand mix). When we make our hypertufa, our aggregates used give us a lighter result and a more porous result than concrete would. Basically this hypertufa recipe is a “type” of concrete but made with our special aggregates of vermiculite or perlite (along with the Peat Moss).
Your vermiculite (it’s brown & with a slightly heavier resulting project) or perlite (it’s white & with a slightly lighter resulting project) is one of the other main components of hypertufa. If we are still using the basic recipe, it would just be a matter of taste whether you want vermiculite or perlite. Some like the white specks of perlite and some want it dark speckled or more blended in with vermiculite. So either of these work just as well. Some say golden glints from the vermiculite enhance their project so they like it better. For myself, I am a vermiculite fan.
Peat moss is the final basic ingredient. This comes in bales and can be sifted to make it less chunky and mix better with the cement and vermiculite. The sphagnum peat moss is mainly what results in the porous nature of hypertufa. The tiny fragments of peat moss will decay over time and create tiny sponge-like breathing holes in the side and bottom of the hypertufa project, even creating tiny anchoring spots for roots and clinging or climbing tendrils.
In place of peat moss, some have decided to go with shredded coconut husks instead. This is called coir. It is a bit more expensive than sphagnum peat moss. If you have an objection to using peat moss, you could use a bag of potting soil or organic potting soil. Just check and see if your bag of potting soil is listed as composed mostly of….yeah, peat moss.
Additives to The Basic Hypertufa Recipe
Fiber Mesh to strengthen your hypertufa project. In most cases, I don’t think this is necessary, but if you make a large piece of garden art, you may want to add a few handfuls of these hair-like strands. For me, this was hard to find. I had to finally go to a local concrete production facility. Here closest to me at the time was Ernst Concrete.
Colorant to give your project an inner color. This will wear off over the years, and in my opinion, it takes a lot of colorant to get a decent amount of color. ( I have only used the liquid type. Powder may or may not perform differently for you.)
So there are your basics with a video about choosing your cement. Some areas package it differently and here are a few examples of that. Sometimes it is just referred to as GP or General Purpose cement.
As you make more and more, you will find that you prefer one over the other and can then really get experimental. Hypertufa is fun to make, and for some people, can make some money selling them locally. Just be sure to practice all safety precautions. More info on the actual Procedure is here under my Making Hypertufa tab. Feel free to browse and let me know if you have any questions