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how to make your own concrete bust/torso.
The following
explains how to make a cast of a torso from mod-roc
and then how to fill this with concrete to create
one or more sculptural "ancient Greek-style" busts.
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Materials check list (for one adult torso):
1. Mod Roc - 2 rolls
2. Petroleum jelly - 1 large tub (200g or so)
3. Duct or Masking tape - 2 rolls
4. Cement - 1/2 a bag
5. Ballast - 1 1/2 bags
6. Water - 2 or 3 watering cans full
7. Drainpipe - 20cm or so length (to enable
stability)
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a.
making a mod-roc (negative) mould.
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1. Liberally
smear a persons torso in petroleum jelly (sometimes
called Vaseline). This is stop the mod-roc
from sticking to them, so do not skimp this stage,
especially if they have body hair! You will
need the petroleum jelly later, so do not use it all
up, expect to use no more than an inch of the tub.
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2. Apply mod-roc
to torso (should cost no more than £3 a roll, search
online).
Cut 50cm
length off of the roll, dip into a bucket of clean
warm water until the strip has soaked the water
(this takes literally a few seconds), then apply
immediately to the torso. Cover the torso in
one layer, rubbing and smoothing the mod-roc
ensuring no bubbles or gaps are visible.
Repeat until your torso is covered in 4 to 5 layers,
paying particular attention to the lower half which
will take the majority of the weight.
The
process could take up to an hour and a half, so warn
the person you are using that their back will ache!
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3. Remove the
mod-roc from the person.
The
mod-roc will become hard within 5 to 10 minutes,
ready to remove within 40 minutes. As it
dries, the mod-roc naturally pulls away from the
body (if your person is adequately lubricated!).
To remove it you can use a combination of a craft
knife and heavy duty scissors. Cut along the
sides and shoulders to create two halves, a front
and a back.
As
you cut the mod-roc off, slide your hand between the
cast and the body so that you can feel if the blade
as it cuts through. If you are careful and
take your time, it is unlikely that you or the model
will be cut.
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4. Smear the
inside of each half of the mod-roc cast in petroleum
jelly.
5. Stand each piece up to re-create the original
whole and tape the outside back together. Lie
the mould down carefully and use mod-roc to cover
the seams along the inside of the mould. Also
use the mod-roc to cover the holes in the shoulders.
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6. Lay wet
mod-rock on a wooden board to make a rectangle big
enough to cover the base of your upright mould.
Stand the drainpipe segment in the centre of this
rectangle and use small strips of mod-roc to affix
it to the mod-roc rectangle. Also use mod-roc
strips to cover the top of the drainpipe to create a
cap for it.
7. Place the
mould over this, directly on top of the mod-roc
rectangle base, with the drainpipe in the centre
inside the mould, forming a sort of spine.
Rewet the edges of the rectangular mod-roc base and
fold it onto the base of the mould. Use more
mod-roc strips to secure it if needed.
You have now created a completely
sealed mould in which to pour the concrete.
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b.
making the concrete torso/bust.
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1. Make a wet
concrete mix. Use the ratio of 1 part cement
to 3 parts ballast and add water from a watering can
until the consistency is something like wet
porridge. With concrete, it is better to use
less water than more, if you make it too wet, add
cement rather than ballast as this will ensure the
concrete is strengthened rather than just made
dryer!
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2. Pour the
concrete into the mould. Take your time and
ensure that the drainpipe does not move around too
much, be sure to keep space around it from the
mould.
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3. Leave to dry
for 6 to 7 hours. Then use a craft knife to
cut it from the bust. Wash the
petroleum jelly off with a wet sponge. The concrete
will still be wet enough to be able to smooth over
any cuts from the craft knife, do this with the wet
sponge. |
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4. After a day or
2 the bust will be dry enough to paint, if required.
Paint with 2 or 3 coats of emulsion for a fine-art
effect. Emulsion seals the concrete adequately
to stop it from powdering on the surface. It
can also be an undercoat for gloss paint, plasticote
spray, acrylic or enamels.
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