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Hypertufa is an artificial stone ( Named for “tufa,” a natural, porous limestone), used to make light-weight, weather-proof garden ornaments and pots.    And you can make it your very own self! 

Hypertufa Party!!

A couple of weeks ago, I decided to try making hypertufa pots with a couple of my crazier, more experimental friends.  Fall is a good time to make hypertufa, as the pots need to cure in a couple stages before you use them.

First, I did some research for the best hypertufa recipe, the best hypertufa videos, (here’s another good hypertufa video) and I looked at lots and lots of hypertufa photos online for inspiration.   We adapted our own procedure from the version found here on The Artistic Garden.

Photos were all taken in the Almostgotit Hypertufa Factory!

Hypertufa Recipe

• 1 part Portland cement (NOT concrete or quikrete!!)
• 1½ parts peat
• 1½ parts perlite (or vermiculite – which heavier, & adds some sparkle)

HOW MUCH?  Two 90-lb bags of Portland cement, 10-15 lbs of perlite, and 2 cubic feet of peat moss made about 10 medium-sized planters (14-20″ diameter bowls)

PREP & SAFETY

•  Wear clothes you don’t mind getting dirty

It’s also recommended to launder your work clothes right after you’re done, and take off your shoes before entering house.  I didn’t get as dirty as I thought.  An apron worked well… lugging things around got my front dirty.

•  Wear a fine-particle dust mask & waterproof gloves

The dust from any ‘tufa mixture is very caustic and definitely can damage your lungs if you breathe it in. Once you’ve got everything mixed and have added the water, then you can take off your mask.

Ingredients are caustic & not skin-friendly. Wear heavy-duty rubber dishwashing or rubber work gloves when mixing dry ingredients and when handling the wet mixture. Another caution: even handling hypertufa that has cured enough to unmold but is still damp can cause skin burns.  Disposable latex gloves work great when applying and detailing hypertufa, allowing you more dexterity than the heavy gloves used for mixing.

•  Last but not least … yes you should wear safety goggles!

We didn’t.  Bad, bad, bad.

Additional hints:

• If you’re mixing up a large quantity of one of these hypertufa recipes, divide the mixture into smaller batches to make it easier to blend.
• Measure the dry ingredients into a large container such as a wheelbarrow. Use a shovel, concrete trowel, garden hand trowel or similar for mixing.  WE GAVE UP AND USED OUR HANDS.  EASIER!
• Make sure all ingredients are thoroughly blended before adding water. Mix and blend more than you think you need to!
• Add The Water Slowly … You Can Always Add More  WORDS TO LIVE BY.
• Next, take a 10 minute break from the whole mixing process. Let the water “soak in” a bit.  This is a good time to serve coffee and chocolate (take your yucky gloves and shoes off, first!)
• Test your mixture for the proper consistency (cottage cheese consistency) by taking a handful of mix. Squeeze it into a ball that will hold together when you open your hand. A little bit of water can slightly ooze between your fingers.  Remember that this mixture must be able to cling to your mold and stay put and not start sagging. 
• How do you know what is enough or not enough water?  The APPROXIMATE amount of water needed MAY or MAY NOT be 1 to 1-1/2 parts water (in relation to the dry ingredients “parts”).  Be on the safe side, slowly add your water to your thoroughly-blended dry mix. Add water until you have a damp mixture. One that is not crumbly but also not oozing with water.

 MAKING A HYPERTUFA BOWL

• We found it easiest to cover the exterior of a bowl. Line or cover your wood, plastic, or metal bowl with a large plastic garbage bag.
• For a portable work surface, put another plastic bag over a piece of scrap plywood (this bag can later be turned inside-out to cover your finished bowl while it’s drying!
• Turn your plastic-covered bowl upside down on your plastic-covered work surface so you’re able to cover the bottom of the bowl with hypertufa. Begin building the mixture around the base of the mold, gradually building up the sides and over the top. Pat and press, pat and press the mixture as you work along. The desired thickness of ‘tufa is about 1½ inches for SMALL containers. 
• Make sure the top and edges are as thick as the sides. You don’t want weak areas in your bowl due to the hypertufa not being applied thickly enough.
• Keep the base of the bowl as flat and smooth as you can.  This means the top of your project, which will become the bottom when it’s flipped over.
• Use a bamboo barbeque skewer, or similar thin object, marked at 1-1/2 inches, to poke through the ‘tufa, allowing you to check the thickness of the walls as you are applying it. This will help insure that you are keeping your entire project 1-1/2″ thick.  It is harder to predict the wall’s thickness than you might think!
• When you’re finished, if you desire a smoother look to your hypertufa trough, smooth the surfaces with semi-wet fingers.  Patting the surface also works well to compact the hypertufa and force water up to smooth the surface.  Turning the worksurface bag inside out so it goes around the bowl instead at this point is helpful, too — you can use the bag to pull up and shape the bowl from the outside before sealing the bowl up inside of it. 
• Create drainage holes: using short lengths of ½” – 1″ dia. dowels, poke the dowels through the ‘tufa until they touch the base of your mold. The larger the trough, the more drainage holes I’d suggest you include. If you don’t have dowels, use whatever you have on hand that can create holes — no one is going to see them anyway when your trough is planted.  They don’t have to be perfectly shaped.  

CURING YOUR HYPERTUFA

Stage 1 (2 to 4 Days)

• It’s helpful to build your pot on a moveable work surface (see above) so you can move it to the drying area without disturbing it too much.
• Carefully place your object into a large black plastic trash bag (or similar) and seal it up tightly. (If your object is too heavy to lift, then do your best to cover with black plastic. Keep in mind you are trying to retain moisture to help the object dry slowly.)
• Many ‘tufa makers will thoroughly mist the object with water before sealing up the bag. As I’ve said elsewhere on these pages, there is no exact science to anything regarding hypertufa. That includes the “best way” to cure it.
• Seal the bag as air tight as possible. We used our bags to finalize the shape of our bowls, and liked the stone-like lines the plastic made when pressed against the hypertufa.  You can inflate the bag a little to keep it off the surface while drying, if you prefer.
• Carry your pot to a spot you are able to leave it undisturbed during the curing.
• After approximately 24 hours you will want to test your new, and still curing, hypertufa object. Carefully open the bag (or uncover) and see if your fingernail can scratch off any ‘tufa. If you can, seal it back up and wait another 12-36 hours. When you can’t really scratch any off (without some difficulty), you’re ready to unmold your object. Your object is still a bit fragile! Remove from the mold carefully.
• If you want to add texture to the object’s surface, you need to do that now before you move on to the next step.
• Caution: when handling damp pieces you should wear your gloves!  Gingerly place your object back into the plastic bag and seal tightly. You can now keep your object at room temperature.

Curing: Stage 2 (1 week – 1 month or more)

• Continue to keep it moist, misting occasionally if needed. Allow it to cure for at least another week but the longer it can slowly cure in a moist environment, the better.
• At this point, most ‘tufa makers will keep the object bagged up for a month or more. (I’ve seen it written that a one month cure time can result in 25% stronger ‘tufa).
• Your new garden art object can be removed and left until it is completely dried … you’ll know if it sounds hollow when tapped.

Curing: Stage 2 (1 week – 1 month or more)

• Continue to keep it moist, misting occasionally if needed. Allow it to cure for at least another week but the longer it can slowly cure in a moist environment, the better.
• At this point, most ‘tufa makers will keep the object bagged up for a month or more. (a one month cure time can result in 25% stronger ‘tufa).
• Your new garden art object can be removed and left until it is completely dried … you’ll know if it sounds hollow when tapped.

Curing: Final step: getting rid of excess lime from the Portland Cement

• Cured hypertufa is very alkaline due to the Portland cement. If you have ever seen a white powdery residue on new cement, that is the free lime leaching out.  Most agree that the lime is toxic to most plants and therefore needs to be leached from the object if you are going to use it as a planter.
• EITHER:  soak ‘tufa planter in a larger container of fresh water, changing water every day for 3 days. (Note: The lime can still burn your skin so wear your gloves.)
• Or If the planter is too large to fit into another container, hose it down once or twice a day for 3-5 days.
• Or best of all, use my approach and leave the planter outside for a few months, allowing the lime to leach out naturally by being rained upon .   After all, there’s still plenty of time before I’ll need them in the spring.

Update, Dec 1: To see what the finished pots look like, click here!

Cross-posted at BlogHer.com