Making
stepping stones is a relatively simple process if a few processes are
followed.
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| A range of examples |
Work
Area
Pick
a work area where the mold can be left undisturbed for 48 hrs.
Prepare the area by putting a protective layer of newspaper or plastic around the work area. Place several pairs of gloves, bags of concrete, chicken wire, mould, stick back plastic, cut glass and water ready to hand. A mixing container is essential, and you should have the reinforcing chicken wire ready cut to size for the mould. A nearby dust bin is a good idea to be able to put waste into without moving wet materials far. Make sure the work area is level and the mould sitting on it is also level.
Prepare the area by putting a protective layer of newspaper or plastic around the work area. Place several pairs of gloves, bags of concrete, chicken wire, mould, stick back plastic, cut glass and water ready to hand. A mixing container is essential, and you should have the reinforcing chicken wire ready cut to size for the mould. A nearby dust bin is a good idea to be able to put waste into without moving wet materials far. Make sure the work area is level and the mould sitting on it is also level.
Design
and positioning of glass
Opalescent
glass is the best to use for stepping stones, as it reflects the
light. Transparent ones appear dark or black.
The
cut line cartoon should have lines at least 3mm wide – up to 6mm is
also suitable. The cement needs to get between the glass pieces.
Cut the glass to the edge of the cartoon lines.
Ensure
the glass pieces do not come closer than 12mm to the edge of the
mould to allow the concrete to form an edge that will protect the
glass pieces.
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| Cartoon, cut glass, and examples of the process |
Placing
and adhering glass
Use clear sticky backed plastic and fix it – sticky face up – over your cartoon. Place the glass pieces firmly onto the sticky plastic. Cut the plastic to the size and shape of the mould to ensure no concrete gets under the glass.
Use clear sticky backed plastic and fix it – sticky face up – over your cartoon. Place the glass pieces firmly onto the sticky plastic. Cut the plastic to the size and shape of the mould to ensure no concrete gets under the glass.
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| Glass placed and ready for pouring |
Preparing
the mould
Put
a separator on the mould – spray on oils can work, but Vaseline is
a more certain separator. All of the mould surface must be thoroughly
coated. Disposable plastic or latex gloves will help with greasing
the mould.
Carefully
lift the sticky back plastic with the glass on it and place it in
mold making sure placed in center.
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| Examples of ready made moulds |
Concrete
mix
If
you are making small quantities of cement, ready mixed concrete for
general purposes will be suitable.
If you are making a number of stepping stones ,mix the concrete yourself as it will be cheaper.
If you are making a number of stepping stones ,mix the concrete yourself as it will be cheaper.
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| A ready mixed quick setting concrete |
Calculating
the amounts: Square and rectangular moulds are easiest – multiply
the length by the width to give the area and multiply that by the
depth in centimeters. This will give you the volume in cubic
centimeters. Divide the result by 1000 and you have the total number
of litres required.
For
circular or hexagonal moulds multiply one half of the diameter (the
radius) times itself and then times 3.14 to give the area. Finally
multiply by the depth of the mould to get the volume. All of this is
measured in centimeters.
You
have seven parts of dry material, so divide by seven and the one
seventh will be the concrete needed, two sevenths the sand and four
sevenths the volume of stones needed. The stones should not be
larger than drive-way type gravel.
You
can of course, just fill the moulds with water and measure the water
required to give you the volumes you need.
Mix
up the dry materials, whether ready mixed or measured by yourself, to
ensure everything is coated with the concrete.
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| Dry mixing and then progressively adding water |
To
get a fine, smooth surface to the top of the stepping stone, sieve
out the stones from some of the mix to give you about 1 cm depth to
pour between the glass pieces without any stones sitting there.
(Multiply area by 1 cm to give you the volume of dry material you
need to put down the top layer.) When you have sieved that amount of
material out, put the coarser material back into the dry materials
and mix again. The stones are important to the strength of the whole
stepping stone.
Pouring
the concrete
Mix
the cement, sand and small stones with about 1.5 times water until a
thick pancake batter. Pour it slowly over the glass to ensure you do
not disturb the placement of the glass pieces. When poured, tap the
sides of the mould with a piece of timber to encourage air bubbles to
rise.
Mix
the remaining dry
materials with water and gently pour half of it into the mould. Then
add the chicken wire for re-enforcement and fill with the remainder
of the cement. The metal is better than the plastic version.
Tap the sides of the mould again to drive air bubbles out of the mixture. There should be no pools of water on top of the cement, as too much water will weaken the concrete, as will too little. If there is excess it should be absorbed with some paper towels.
Tap the sides of the mould again to drive air bubbles out of the mixture. There should be no pools of water on top of the cement, as too much water will weaken the concrete, as will too little. If there is excess it should be absorbed with some paper towels.
This
is the time to sign the stepping stone. There is a relatively short
time after about an hour to do this while the concrete is stiff
enough to hold the marks and not too stiff to resist any marks.
Removing
Let the stone cure at least 48 hours before removing from mold. Do not move mold once the concrete is in it – you will get concrete between the contact paper and glass which causes the top to be uneven and more importantly can cause cracks in the concrete.
When you are ready to de-mould, turn the mould face down onto a board. Ease the sides away from the concrete gently. It may drop out with just that encouragement. If not, press gently at the centre of the mould until it beings to release. Finally, if necessary tap the sides of the mould with a rubber mallet. Difficulty in removing the stepping stone usually relates to too little separator.
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| Pealing off the plastic |
Turn
the stepping stone over with the assistance of the a board on the
back. Look at the top of the stone and decide whether it is fully
cured. If not, leave the sticky plastic on for a few more days
before gently pealing it off. If you can see that there are gaps or
depressions in the surface, you will need to take the plastic off
immediately and make a small mix of concrete and sand (1:2) with
water to fill those blemishes.
Clean
the concrete from the glass before fully cured as it is more
difficult to get the dry concrete from the glass without scratching
it.
Curing
Let the stepping stone sit for 30 days before sealing. You can leave them flat or stand against a wall. In either case you should put some paper between so they don't get scratched. Clear concrete sealer, with two to four coats brushed on, will be sufficient for protection from moisture. Weather, temperature and time of year play a big part in the curing and de-molding. Do not put your mold in the sun to cure, as that dries out the water before the chemical reactions can occur. Concrete needs to cure slowly to achieve its maximum strength. For the same reason, you do not want to leave the curing concrete in freezing conditions as that will also stop the chemical reactions. If it is wet, you need to protect the curing cement from the rain as too much water can weaken the concrete too.
