How to make an alpine trough with hypertufa

Stone can be an expensive material, however. A simple alternative is to make a trough that looks like stone. It’s not as hard as you may think! This guide will show you how to make a mix called ‘hypertufa’ and how you can use it to make stone-like containers.

What is hypertufa?

Tufa is a porous natural limestone rock. Over 90 years ago, it was discovered that alpine plants grew very well on it (as you can see in the images above).

Hypertufa cement-based substitute that you can make yourself. It can be used to make simulated stone sinks or even to custom-make your own rocks!

Why make hypertufa?

• Pieces of natural tufa are hard to find and very expensive.
• Tufa pieces large enough to construct a sink are even more scarce.
• The materials needed to make hypertufa are easy to find and inexpensive.

What do you need?

• Coarse sand: Look for concreting sand, coarse sand or grit sand. Pass through a garden sieve (about 7mm) to remove any larger particles.
• Composted bark: A good, environmentally-friendly alternative to the commonly used moss peat. Choose a fine grade and pass through a sieve as before.
• Cement: Buy fresh Portland cement just before you intend to use it. Using old cement won’t give as high quality results.

How to make it

Depending on the finish you desire, there are various recipes you can follow:

TIP: The tufa recipe creates a very porous product that is vulnerable to frost. If you live in a very cold area, toughen it up by slightly reducing the volume of bark.

How to mix it

You can usually mix the materials straight from the bag. If the sand is very wet though, allow it to dry out first.

Mixing can be a messy process! If you’re making several batches, we’d recommend buying a Spot Board (available from most DIY stores).

Method

Measure the appropriate volumes and mix thoroughly. Slowly add water and continue to mix. Aim to add just enough water to completely wet the mix, but not so much as it goes ‘sloppy.’

TIP: Use gloves when handling the mix. Cement and wet hypertufa are corrosive and strong skin irritants.

How to make a hypertufa sink

You can create a sink in many ways. Below are some of the preferred methods used by alpine enthusiasts:

Fishbox

Expanded polystyrene fishboxes are widely available. They’re excellent for creating a light but robust sink.

Method (based on an average-sized box)

• Cut two drainage holes in the base (min. 2cm diameter)
• Wrap small-gauge galvanised chicken wire around the box
• Apply the mixture to the bottom first (by hand). Aim for a layer at least 2cm thick
• Place the box upright on a polythene sheet
• Continue coating the box up the sides, over the rim and at least 5cm down the inside.

Glazed sinks

This process is similar to fishboxes, but it can be tricky to get the mixture to stick to the glazed surface.

Method

• Thoroughly clean the surface
• There are two options for creating the perfect base:

1. Use a hammer to chip off small areas of glaze across the outer surface
2. Coat the outer surface, rim and 5cm down the inside with a PVA adhesive. (Leave to dry to the point where it still feels tacky.)

• Apply the hypertufa mix by hand, in the same way as the fishbox method.

Casting a solid sink

Casting a solid sink is the traditional method.

Method

• Use two stout cardboard boxes, which can be ‘nested’ (leave about 50mm between them).
• Set the outer box on a flat surface.
• Create drainage holes: stand two 50mm lengths of dowel or broom handle on the base.
• Make a more fluid mixture and pour in, levelling to form the base.
• Lower the inner box into place and fill with sand or bricks to hold. (The outer box will need similar support.)
• Continue adding the mix between the sides of the two boxes, tamping down at intervals to remove air pockets.

Finishing touches

The mix sets slowly, so cover with damp hessian sacking or a polythene sheet for a day or two. You can then remove any cardboard boxes.

Genuine stone troughs tend to have irregular surfaces. To create an authentic finish, (when still slightly soft) strike the surface with a steel chisel, broad screwdriver or scrap of wood.

Round off any sharp edges by rubbing over with a stiff brush.

The hypertufa will continue to cure and harden over the next couple of weeks. Wait until your sink is fully cured before moving it to its planting position.

Hypertufa rocks

You can also use the hypertufa recipes to create tufa-like rocks.

Method

• Drop the mixture into a light-gauge polythene bag
• Place the bag into a cardboard box for a rectangular shape
• ‘Bashing’ when set can add a suitably rugged shape.

Happy trough-making!