Preparing glazed sinks to make ‘fake’ stonework (hypertufa)
Heavy sinks are best mounted on stones or old bricks, approximately 15-25cm (6-9in) high, and prepared in situ. Smaller ones can be prepared where convenient and moved to a permanent site when dry. Drying usually takes about three weeks, after which sinks can be planted.
A simple technique to prepare old glazed or domestic sinks to look like stonework is as follows:
- Remove any metal fittings
- Clean and wash the sink thoroughly and allow to dry
- Apply a coating of Unibond or other adhesive (obtainable from most ironmongers' stores). Allow this to become tacky while mixing the hypertufa as follows:
Traditional mix (all parts by volume)
1 (or 2) parts peat substitute
1 part sharp sand
1 part fresh Portland cement
The peat-substitute in the mixture provides the stone colouring and variations in the quantity of peat-substitute used will give corresponding variations in colour of the finished product. Too much will give a less durable finish.
- The best time to carry out the work is during cool, but not frosty, weather as the coating mixture will then remain workable for longer than it will in warm, dry conditions
- Wear household gloves – hypertufa and cement are corrosive
- Avoid making the mixture too wet. A 9 litre (2 gal) bucket full of the complete mixture is approximately sufficient for coating an average-sized sink, so start with a half bucketful, treating a section at a time. Add the water gradually
- Apply the mixture to the tacky adhesive. This should extend over the rim, 5-8cm (2-3in) down the inside, and 8-10cm (3-4in) under the base, so that on the finished sink no glazed surface is visible
- Apply two or three coatings for greater durability and resistance to frost damage
- To simulate stonework, mark or jab the surface with an old paintbrush or chisel as the material dries
- To encourage moss and algae to give an appearance of age, apply liquid manure with a paintbrush
Traditional stone troughs, and even glazed sinks, are now becoming difficult to obtain, although reproductions are available. As an alternative, new troughs can now be entirely made from hypertufa.
Prepare the mixture as for coating but add a little more water.
- Find two wooden boxes that will fit inside one another, with a cavity of 5-7cm (2-3ins) between them.
- Stand the larger box on blocks so it may be lifted easily once finished.
- Pour two thin layers of the hypertufa mix into the base with strong wire netting between the layers and parallel to the vertical sides.
- Press two 5cm lengths of thick dowels or pegs through the hypertufa to make drainage holes.
- Fit the smaller box inside the larger, with wire netting between the two, and fill the space with the mix, tamping it down to remove air pockets. For a single trough strong cardboard boxes can be used as a mould.
- When the cavity is full, cover the trough with a sheet of plastic for at least a week while the mix sets and protect the trough from frost, if necessary.
- When the mix has set hard, remove the boxes and dowels. If the boxes do not slide off easily, ease them off carefully with a fine chisel and a small hammer.
- Roughen the surface of the trough with a wire brush and paint on a coat of liquid manure to encourage algal growth.
You can use a fish box to create a lighter trough;
- Work on a large sheet of polythene
- Make two drainage holes of 2cm (¾in) in the base
- Wrap the whole box with small gauge chicken wire
- Start by covering the base, ensuring the hypertufa mxture is well packed through the wire
- Make the layer no less than 2cm (¾in) thick
- Carefully turn the box right side up and work on covering the sides and down 5-8cm inside the rim