| Q: What is
Plaster of Paris? |
| A:
Plaster of Paris, or simply plaster, is a type of
building material based on calcium sulphate hemiydrate
(gypsum), nominally CaSO4 ½ H2O).
It is created by heating gypsum to about 150º C.
Heating also takes place when re- mixed with water
(casting), hardening to a smooth solid which does not shrink
or lose volume, because it hardens before all the water can
evaporate. It is
a common building material as well as a versatile medium in
sculpture. |
|
| Q:
What is a casting? |
| A:
A work which has been produced by moulding.
The positive |
|
| Q:
What does
exothermic mean? |
| A:
Heat set up
during the cure of a plaster casting. |
|
| Q:
What is fibre glass? |
| A:
Very slender
fibres made from glass. |
|
| Q:
What is a Release Agent? |
| A:
Material applied
to surfaces to aid parting. |
|
|
Q: What
is Patina?
|
| A:
The finished
colour of the surface of a casting. |
|
| Q:
What is scrim? |
|
A: A
course woven fabric, usually made from jute used to
re-enforce plaster of Paris castings.
|
|
| Q:
How do I get rid
of air bubbles in a casting? |
| A:
Vibrating a
mould during the setting process encourages air to escape |
|
| Q:
What is an
armature? |
| A:
An internal
support. |
|
|
Q: What
is the best way to mix plaster of Paris?
|
| A:
Always add the
plaster to the water. |
|
| Q:
How do I remove
mildew from my castings? |
|
A:
Fully dry your plaster casting and wash spots off
with a dilute solution of bleach.
|
|
| Q:
My plaster mix sets before I pour it into the mould? |
| A:
You can delay the setting time of the mixture by
adding sodium citrate or citric acid to the water prior to
adding the plaster powder. |
|
| Q:
How do I speed up the setting time of my plaster
casting mix? |
| A:
Add potassium sulphate to the water prior to adding
plaster. |
|
|
Q: The
ears & nose of my model dogs are always are imperfect
and have bubbles which ruin my plaster craft – how do I
eliminate these
|
| A:
Use a very soft (sable like) long haired paint brush
and stipple/agitate it within the plaster filled mould in
the areas of nose and ears – this should dislodge bubbles. |
|
| Q:
I am trying to make some hill and rock scenery for my
model railway – how do I create a mountain without it
collapsing every time I apply plaster? |
|
A:
Construct an armature of wire and cover it with wire
mesh (chicken wire) – then cover the mesh with strips of
plaster bandage – allow to dry and paint.
|
|
| Q:
I am making plaques and hanging plates – what is
the best way to attach a hanging hook? |
|
A:
Just before the plaster hardens in the mould push a
piece of wire bent like Ω into the plaster and allow 2
set – copper, galvanised or plastic garden wire are best.
|
|
| Q:
I keep breaking my models when taking the latex mould
off – how do I stop this? |
| A:
Allow a little longer for the plaster to set and
lubricate the outside of the mould with liquid soap so the
mould will slide back over itself like a rubber glove. |
|
| Q:
How do I make the paint stick to the surface of my
plaster models? |
| A:
Allow to thoroughly dry first – if still a problem
seal the surface of your plaster casting with a sealer like
shellac or gesso. |
|
|
Q:
I want to make my own moulds – what materials are
available
|
| A:
Latex rubber, two part silicone rubber and alginate
are all used a great deal |
|
| Q:
I want to try body casting or life casting but I
don’t want the plaster bandage to stick to my skin – how
do I stop this? |
|
A:
An application of baby oil, Vaseline or KY jelly will
usually prevent this – better still apply safe dental
alginate over the skin after the oil, allow to set and then
apply the plaster bandage
|
|
| Q:
I want to complete a ‘personal intimate’ gift for
my partner – what is the best way to go about this |
| A:
The materials are very safe to use if done correctly
– for in-depth instructions – click here |
|
| Q:
Can I cast a very young baby's hand or foot. |
| A:
Yes – the baby casting kit includes all safe
materials and all details will be reproduced |
|
|
Q:
Can I keep my rings and jewellery on when moulding
|
| A:
Yes – and when you use our moulding material these
will be reproduced in very fine detail and add character to
your plaster cast |
|
|
Q:
Is pregnant belly casting easy and safe to do
|
| A:
Yes the process is extremely safe for baby and easy
to carry out – using our belly casting kit the whole
process should only take 40 minutes |
|
| Q:
Can I take a mould of my pets paw |
|
A:
Yes – this process is ideal when using our pet
print kit and our materials don’t stick to the paw, skin
or fur
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