Hypertufa 101: Make One Trough or Throw a Party
We had so much fun at the Mid-Atlantic Spring Swap, we had to get together again, ASAP. As it turns out, a bunch of us were really interested in trying our hand at hypertufa, but we just hadn't gotten around to it or found the idea just a little intimidating.
So, I hosted a Hypertufa Party. We had a wonderful afternoon and made an assortment of containers using different molds and techniques. Here's what we learned along the way.
What is hypertufa? A lightweight version of concrete made with
peat moss and other materials in place of sand and gravel.
Finished hypertufa containers have the look of old stone.
Safety First! You'll need dust masks to protect your lungs when working with the dry cement and gloves (latex or nitrile) to protect your hands.
Portland cement -- that's "cement," not concrete or patch mix or anything else that has sand or other aggregates added, just cement. We're talking 94-pound bags, so ask for help loading your car!
Peat moss, fluffed and slightly dampened. Sift through a screen if you want, or just pick out any twigs or chunky bits. For one bag of cement, we used perhaps half a bale of peat moss.
Perlite and/or vermiculite. We used perlite and didn't sift out the bigger pieces, so we had some pretty rough-textured mix. Experiment with different combinations and see what you like.
Sand. A layer of damp sand in a shallow box can help support your project, especially if you're putting the mix on the outside of your mold. You can also scoop out or mound up damp sand as a base for various hypertufa shapes. I estimated we'd need half a bag of sand per person and had a lot left over, but we'll use it in our next project.
Molds. Nursery pots, plastic planters, and bowls are obvious choices. Once you start looking around, you'll find inspiration in cardboard boxes, pieces of styrofoam, containers from the recycling bin, even different items taped together to make an interesting shape.
Plastic bags. Garbage bags, department store bags, grocery bags, zip-top bags of various sizes - all will come in handy. You'll want bags to line your molds and help shape your projects, and you'll need to seal your project inside a bag to keep it damp while it sets up.
Miscellaneous helpful Items: cooking spray, bamboo skewers, wood dowel or other item for making drainage holes, trays & buckets for mixing, work tables, sturdy boxes or boards to put under your project so you can move it without disturbing it later, a container that will hold enough water to submerge your piece the next day.
We set up our work area in the garage, where it was easy to make a space by pulling the cars out. I had a couple of tables, and several other people brought folding tables also, so we had a good amount of work space for 15 people. We could have spread tarps and plastic tablecloths to protect the floor and work surfaces, but my garage isn't nice enough to bother.
While some of us distributed materials around the tables and discussed mold options, others put together the dry hypertufa mix. Just as when you work with concrete, the standard recipe is 1 part cement plus 3 parts aggregate. We kept our recipe simple:
|2 parts Portland cement + 3 parts peat moss + 3 parts perlite|
We used a 5-gallon bucket to measure the ingredients into a large wheelbarrow. Starting with the damp peat moss helped keep the dust down, but everybody was "good" and wore their dust masks. Our "mix master" Ric was ably assisted by a couple of the other guys. The dry mix was scooped into dollar store buckets, ready to go.
Plywood boards or sturdy boxes from Costco make good work surfaces. Rather than trying to lift your project into a plastic bag at the end, you might want to open up a bag and scrunch it down into a flat ring around your project before you start, so you can just pull it up and over to seal it when you're done. Also consider if your project could use support from a layer of damp sand: flat to support a rim, scooped to support a ball, mounded to shape a bowl.
Decide - are you an "innie" or an "outie?" For your first container, it's easiest to choose a mold whose shape will be the outside of the container, with the hypertufa packed on the inside. Many of us, however, dove right in and used their container to shape the inside of the mold, flipping it upside down and packing the ‘tufa on the outer surface.
Whatever you use, we found molds were easier to remove when lined or covered with plastic and coated with cooking spray. If you choose a mold that won't simply lift off to un-mold because of an indented band or a deep texture, be prepared to do some serious cutting to remove it.
At this point, we took a break and went inside to cool off with drinks and snacks. If you take a long break, protect your dry mix from moisture by sealing it inside water-tight containers or gallon zip-top bags.
Join us for the second part of this tutorial, "Mixing, Molding, and Making Your Container," and discover what hypertufa has in common with mud pies and snowballs.
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A big THANK YOU to the Mid-Atlantic Gardeners who joined me for a fun workshop party! Thanks also to HollyAnnS for the photo of Ric's hypertufa trough used in the thumbnail image. All other photos by Jill M Nicolaus