BASIC PLASTER CASTING -
ONE PIECE MOLD
One piece plastic plaster of paris casting molds are simple
to use and make great projects for schools, churches and
family time!

For this project, we used our
STAINED GLASS AMEN
PLASTER MOLD (02-0075), CLASSIC ACCENTS
METALLIC PAINT POTS, LIGHTWEIGHT HANG-A-PLAK
and
CLEAR PLASTIC SPRAY.  Also used was plaster of
paris, blue spray paint, blue painter's tape and a mixing
bowl (these items are all available at hardware type stores).
Prepare your work area.  Cover the work area with a drop cloth or similar
item to prevent plaster spillage from damaging anything.  Plaster is a very
fine powder and can be quite messy.  Wear a respirator and / or gloves if
directed by product packaging to do so.

Pour your plaster of paris into a mixing bowl.  Once you use the bowl for
plaster, it will not be good for anything else so don't use anything nice.  
Leave enough room for water to be added.  Plaster of paris generally calls
for two parts plaster to one part water, but be sure to follow the mixing ratio
called for on the packaging.
Using a spoon, make a well in the middle of the dry plaster.
Add water according to the directions on the plaster of paris
packaging.  We pour right into the well we formed in the last step.   
DO NOT STIR!  A chemical reaction that leads to hardening of the
plaster starts as soon as you stir plaster of paris and water together.  

Instead, allow the water to soak into the plaster.  Bubbles will rise to
the surface as the water is absorbed.
The video to the right shows the bubbling that occurs as
water is absorbed into plaster of paris.   This is an expected
reaction.  Once the bubbling stops, you are ready to move on.
Once the water is fully absorbed, stir the plaster of paris mixture until it is
smooth and approximately the consistency of a thick milkshake.  Some
chunks may remain in the mix.  This is to be expected and will not impact
the quality of your finished product.  Plaster can be mixed with a spoon, a
stick or a mixing drill bit.   For large projects, we recommend using a drill
with a plaster mixing bit.
The video to the right shows the approximate desired
consistency of plaster of paris when it is ready to pour.
Once your plaster is ready to pour, spoon or pour it into your mold.  
You may spray the inside of the mold with vegetable oil spray (such
as Pam) prior to use.  This step is generally not needed and we
rarely do so.

Add enough plaster to your mold to completely fill it.  As best as
possible, do not overfill the mold as this will later create the need to
trim away excess dried plaster.
After enough plaster is added to your mold, hold the mold by one side
and "vibrate" it.  This step will help the plaster settle into the mold and
release air bubbles that may be trapped in the mix.  This step also
ensures a smooth back to your finished casting.
This video shows how to "vibrate" a mold.  Note that there is very
little actual movement of the mold during this step.  Air bubbles
released from the plaster mix can be seen rising to the surface in
this video.
For this project, we will be adding a Lightweight Hang-a-Plak to our casting.  
These simple wire hangers are added to the wet plaster mixture to provide a
hanging point for your casting once it sets.
Add your Hang-a-Plak to the plaster while it is wet.  Slide
the open end of the hanger into the plaster, leaving the
hanger exposed from about the neck up.  

Be sure to check your mold to ensure that the hanger is
added to the top center of the finished casting.
Allow your mold to set.  Plaster of paris can be unmolded in
about 30 minutes, though a wait of  2 to 4 hours is safer.

Once your casting is set, it will drop easily out of your mold.  
Make sure to remove the casting into your hand - or over a
soft surface - as the plaster will be somewhat fragile once
set.
Once released from the mold, you will have a smooth, shiny and
ceramic like casting.

Now let's paint!
Almost any kind of paint will work with plaster.  We are going
to start by spray painting everything but the "frame" of the
mold.  To protect the frame, we applied blue painters tape,
ensuring the tape was fully sealed all the way around,
We took our casting outside and spray painted it.   Once the
paint is fully dried, simply peel off the painter's tape and you are
ready to move on!
We painted the frame of the mold using a copper
colored paint from our metallic paint pot set.
Once the frame was painted, we used a silver paint from the
metallic paint pot set on the letters.  Because of the blue
spray paint background, it took a few coats to give proper
coverage.
To give the casting a metallic "background" we mixed a drop or
two of paint into a few drops of water.  We brushed alternating
watered down colors into the "panels" cast into the mold.
As you brush the watered down colors onto the mold, the
water and paint mixture will pool up in the low spots.   The
water will evaporate and/or be absorbed into the plaster,
leaving behind only the faint paint.
Once all of your paint dries, you will be left with a
beautiful piece of art you can hang and display.
We finished the casting off by spraying on a few
coats of our clear plastic spray.  This high gloss
spray gives the finished product a professional sheen
and helps protect the plaster from water damage,
chipping, etc.
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