Lava Rocks

Lava rocks

Creating your own rockery masterpiece has never been made so easy as with this expansive concept and integration of Lava Rocks in your garden.

What you will Need

Flat board or surface to work on
Expanding foam filler
Silicone rubber mould product (available at art shops)
Tile adhesive
Fine river sand
Building stone (12 mm)
Colour oxide
A bucket or similar container
Damp river sand

Hand saw or cutting blade, small paintbrush, small hammer, steel trowel

Lava rocks

1. The first step is to make foam ‘rocks’, which will then be used to form the silicone moulds. Follow the instructions on the foam filler can, which should be: Shake the can to mix, and carefully screw the nozzle onto the valve, facing it away from you (and not at anyone else’s face).

Hold the can upside down and spray a small amount of foam onto a flat surface. Practice spraying in a circular movement to create a round shape with as many lumps and bumps as possible. Note that it does not have to be a perfect circle and that it will expand to about twice its size.

Allow it to dry for 24 hours. When drying, the foam will expand to form a rugged-looking sphere. Using a hand saw, cut off the flatter side of the foam to create one level side.

Lava rocks

2. Mix the silicone rubber mould material according to the instructions (this will involve mixing the various elements together and adding the activator). Note that you have to work relatively fast once the silicone is mixed in order to finish your mould before it starts setting.

Paint the silicone onto the foam ‘rock’, working it into the crevices and all the way down to the board it sits on. Extend the silicone into a circle onto the board (and around the rock) to work as a lip for the mould. Allow it to dry for 24 hours. Peel the dry silicone mould from the foam. Repeat step 1 until you have made three or so moulds.

3. Fill a bucket with damp river sand, dig a hole in the centre and place the rubber mould inside it. Firm the mould into the sand by pushing it down and then check that the lip of the mould is level. The river sand provides support for the mould when it is filled with cement.

4. Mix 2 parts fine river sand, 1 part 12 mm building stone, 2 parts cement, 250 g oxide and enough water to form a runny concrete mixture. Make enough to fill all of your moulds. The oxide is to colour the mixture, so you can change the quantity but remember your ratios so that when you make more you can keep the same colour and appearance.

5. Pour the cement mixture into the mould, filling it right up to the lip, and agitate it with your trowel to make sure it flows into all the crevices. Keep moist or cover and allow the cement to cure for at least 24 hours.

6. Peel off the mould. Repeat steps 3-5 until you made have enough cladding to cover your wall.

7. Mix up tile adhesive and apply it to the flat edge of the lava rocks cladding tiles, then press them onto the wall. You may need to support the rocks while the adhesive dries. To finish off your newly clad wall, plant between the cladding or train a climber up and around the lava rocks.

The Gardener