Metal Casting Zone Info Blog

Posts Tagged ‘plaster’

Guidelines of making Plaster craft

Plaster craft is a complex process unless you are aware of its ins and outs. Given below are a few guidelines of making plaster craft.

Step – 1:

Cover your work surface with an old newspaper or a vinyl peace. As you may see from this photo plaster casting is a bit messy, so it is essential to protect your countertops.

Step – 2:

Check the mould to ensure it is clean and dry. Any dirt might show on the finished casting.

Step – 3:

Many moulds cannot sit flat on the counter, therefore, it is important to give them support while using. The most simple process is a zip lock bag filled with a few pounds of rice. Rice bags are convenient to pack and store when not being used and are made of common materials most people find handy. A box of sand will also work well but it is more difficult to store it when not being used.

Step – 4:

The surface tension of the water tends to trap air leading to pinholes in the finished casting. Airid is a product meant to break that surface tension, reducing the chances of trapped air. Spray or wipe a thin coat of Airid into the mould.

Step – 5:

Wiggle the mould down onto your rice/sand bag till it looks level. You are now ready to mix plaster.

Step – 6:

To find out how much plaster will it hold fill the mould with water. It is the exact amount of water you will need. Add a bit more and weigh it on scale.

Step – 7:

Plaster should always be added to water and never vice versa. Sprinkle it in slowly to allow it to absorb water.

Step – 8:

Let the mixture remain undisturbed for 2 minutes so the plaster absorbs all water.

Step – 9:

For coloring, pigments should be added now.

Step – 10:

Utilize a potato masher to mix thoroughly for about a minute. Small amounts can be mixed with a stick.

Step – 11:

Pour the plaster in a corner of mould and let it flow across the complete mould. On deeper moulds, pour it down the side of corner to avoid entrapped air.

Step – 12:

Once the mould is poured, wiggle it to dislodge any air which may have remained in the mould.

Step – 13:

Periodically feel the mould. When the mould is warm to touch, the plaster casting may be removed.

Step – 14:

Gently flex the edges of mould to break sides of casting loose.

Step – 15:

Hold the mould just above the rice/sand bag. Use pressure gently to take out the casting.

Step – 16:

After casting is out, set the mould to be cleaned.

Step – 17:

Utilize a knife to cut the sharp edges off the back of the casting. For fast drying it should be put where it gets air from all angles.

Step – 18:

When fully hardened, most of the plaster will flake off or breakout the plaster.

Step – 19:

Flex the blade of the plaster blender to flake the dried plaster off.

Step – 20:

Wipe off tools and moulds for final cleaning up.

Step – 21:

If you utilize a rice bag any drips may be removed by flexing the bag. For sand box, just pick out any plaster that has fallen on sand.

Step – 22:

Pack up your moulds, tools and plaster. Throw away the old newspaper with which you had covered the working area. If you had used vinyl piece, dust it and wipe with wet cloth.

There are generally to ways to have your own piece of custom jewelry produced if you want to create one and the first way is to go to a jeweler that makes custom jewelry and have them produce it to your specifications. The other way to have it made is to create or sculpt it yourself in wax and then have a jeweler cast it in gold or silver for you.

This is basically the way that most all rings and bracelets are made, although there is finishing work that has to be done after it is cast, the basic form of the creation is determined in wax. Its called the “lost wax method” and it has been in use for thousands of years. Your idea is first created in wax by using sculpting or dental wax. Standard paraffin wax won’t do because it is too hard and stiff and bees wax is too soft.

The wax ring or bracelet is then given to the jeweler who then encases the wax sculpture in plaster. After the plaster that incases the wax ring or bracelet has cured and dried it is placed in a hot kiln so the wax piece inside of it can melt and burn out. What is removed from the kiln is a chunk of plaster that has the hollow shape of the ring or bracelet in it where the wax was.

Jewelers use a centrifugal caster that spins around as the molten gold or silver is forced in to the hollow place in the chunk of plaster by the centrifugal force. After the gold or silver inside of the chunk of plaster has been allowed to cool the plaster is chipped away to reveal the jewelry piece where the wax ring or bracelet once was.

Have you ever wondered as you looked at a piece of gold jewelry just how it it was made. How did the jeweler start out with raw bulk product and end up with the finished product. Jewelery is created using many methods but the most common method is by the “lost wax” casting method. It was developed in ancient times and it is still used to this day, although modern tools are now used.

The reason that is is called lost wax is, because the object that is to be created is first sculpted out of wax to the exact specifications that the finished product is going to look like. After the wax sculpture is completed it is then encased in a silica encasement or in the case of jewelery it is then encased in plaster. Then after the plaster encasement has hardened and dried it is put into an oven or kiln. This will cause the wax to melt and burn out leaving its hollow image inside of the plaster encasement.

Then the plaster encasement with the hollow shape of the piece of jewelry is placed into a casting centrifuge which is a device that will use centrifugal force to drive molten gold down through an opening in the chunk of plaster where it will fill the hollow spot left by the wax melting out. After it has cooled the plaster is broken open to reveal a piece of gold jewelry where the wax sculpture once was.

Its the same technique that is used to create larger bronze sculptures, only with bronze it is done on a larger scale and the centrifugal caster isn’t used. The lost wax casting method was what was used to bring civilization out of the Iron Age and into the Bronze Age. In ancient times primitive metal smiths would use bees wax to shape objects such as axes and arrow heads. These was objects were then encased in clay and placed in the bottom of fire pits to burn off.