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Using 3D Chocolate Molds
For Solid Plaster Casting
By Bob Sherman
molds are well suited to plaster crafting and they are very inexpensive. This
article will explain how to use 3D chocolate molds for making solid plaster
castings. 3D molds are sometimes referred to as assembly molds because they
have two or more parts that need top be clamped together.
Important - This method works well for pieces up
to approximately 4 inches in diameter - sizes larger than that should be hollow
molded which will be discussed in a future article. Use of this method
on larger molds may damage the mold because of the heat generated as the plaster
PLEASE NOTE!! - Plaster crafting
is fairly safe if you observe these safety rules when mixing plaster. Once
hardened there is little or no hazard from handling plaster items:
- Plaster is very alkaline and and exposure to
high dust levels may irritate the skin, eyes, nose, throat, or upper respiratory
tract. Wear a dust mask, eye protection, and rubber gloves when mixing plaster.
- Do not wear contact lenses when working with
- Plaster generates a lot of heat when setting
- never use plaster to make casts of body parts.
- Keep away from children or pets.
- Other safety precautions may apply depending
on the plaster product you use - read the directions.
Plaster is used throughout this article to describe
casting products containing mostly plaster of paris. The two most common are
plaster and hydrocal. Either type will work for this.
- Plaster is generally 100% plaster of paris and
is called a variety of names depending on the manufacturer. These include:
Plaster Of Paris, Casting Plaster, or just plain Plaster.
- Hydrocal is a mixture of plaster of paris and
portland cement and is called a variety of names depending on the manufacturer.
These include Hydrocal, Hydrostone, and Ultracal. Typically hydrocals are
3 times stronger than plaster and more dimensionally stable. For castings
with thin areas hydrocals are a good choice.
Plaster Casting Supplies
The following plaster craft supplies will be needed
to follow along with this article. Clicking on the item name will bring you
to that item's page with a full description and ordering information.
||A 3D chocolate mold is needed. A Happy
Bunny Mold was used here.
||Needed to hold the mold halves together.
For a mold this size two packages are needed. If you prefer, binder
clips from the stationery store may be used.
||A flexible mixing bowl simplifies cleanup,
but you may use any plastic bowl.
||This requires a power drill to use, but makes
blending the plaster much easier. If you don't have a power drill, a
potato masher may be used to mix the plaster manually. For very small
batches you could even use a stick.
||Optional, but recommended. This will help
eliminate air bubbles in your castings.
||Plaster was used here. We sell these to accommodate
our customers, but you may wish to source it locally since the shipping
cost is high due to the weight. Plaster may be found in most home centers
and hardware stores. Hydrocal is much harder to find locally.
||Optional. Plaster can be mixed by guesswork,
but a scale will allow good repeatable results every time. I use an
55 scale for most plaster work, but any moderately accurate scale
that can weigh in 1 ounce increments should suffice.
||Something to hold the mold upright. I normally
use an appropriately sized box.
||I use a standard utility knife but any semi
sharp knife will suffice.
||To support hangers if necessary.
Step By Step Instructions
|1. Use a scissors to trim away
the mold sheet leaving 1/2inch of sheet around the mold cavity.
||2. Use a sharp knife to carefully
cut an opening on the bottom of one half of the mold.
|3. Visually align the two halves
and clamp together.
||4. Fill the mold with cold water
and pour it into your mixing bowl. Add a couple extra ounces. If you are
using a scale, calculate how much plaster is needed for that much water.
Always use cold water because warm water speeds the hardening process.
|5. The plaster is sprinkled into
the water slowly. If you are not using a scale, continue until you have
a mound approximately one inch higher than the water. Let it sit undisturbed
for a few moments to allow the plaster to absorb the water.
||6. Mix until smooth. It is important
not to over mix as that will cause the plaster to harden faster which
may make it start to set in the bowl.
|7. Fill the mold and allow it
||8. When it becomes warm to the
touch, it may be de molded.
Disclaimer: The information presented here is accurate
to the best of my knowledge and common plaster crafting practices as of the
time of this writing - March 2007. The author and the publisher accept no
liability for the use or misuse of any of the information presented in this
article. This article is presented for informational purposes and is used
at your own risk.
Author: Bob Sherman
Publisher: Bobby's Craft Boutique Inc.
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