Source(s):
http://www.castcraft.com/mcfaq.htm
What is a model? What is a mold? What is a casting material?
A model is a 3-dimensional object you use as a pattern so you have something to make a mold of. That would be your action figure in this case. Without specialized equipment, you can't make a mold of an idea or a drawing. You must first turn the idea or drawing into a 3-dimensional object by sculpting, carving, construction, and so on.
Specialized pieces of equipment called "rapid prototyping machines" are able to take computer CAD drawings and create a mold or a part directly from a 3D computer model, but this is not yet something the home craftsperson would find affordable.
A mold is something that will give a certain shape to a casting material.
A casting material is a material that will take on and keep the shape that a mold gives.
You can make a very accurate mold in just a few seconds as a demonstration. Dip a coin (your model) in some water, press one face into a lump of "Silly Putty" (your moldmaking material), and remove it. You have just made a mold! You will notice that every feature of the coin is "reversed" in your mold. Now if you have some plaster (a type of casting material), you can pour it into your mold, let it set, and remove a reproduction of the coin face - your casting. You go through all these steps so you can end up with a copy of your original model. The Silly Putty mold will probably distort as you remove the coin and as you remove the casting. Permanent molds made with materials intended for moldmaking hold their shape so you can use them many times and get the same results each time.
How come I hear about "molded products" all the time?
People who make plastic products commercially using various types of machinery don't usually talk about "castings" or "cast products". They refer to things made in molds as "molded products" - for instance, "injection molded" model airplane parts. To make it even more confusing, they refer to materials that go into molds to make parts as "molding" materials, such as "injection molding resins".
Artists and craftspeople usually use "moldmaking materials" when talking about materials to make a mold, and "casting materials" when talking about materials to make a part in a mold.
If you hear someone talk about a "molding material", you need to ask if they are using it to make a mold, or using it to make something in a mold.
Is it difficult to make a mold?
If you use modern rubber materials, moldmaking is usually quite easy. The easiest type of mold to make is for an object like a plaque. You can just put the plaque in a box, pour rubber moldmaking material over it, let the rubber cure, and you're done. With new clear rubber materials, you can even make molds of very complicated objects in the same way - by putting the object in a container, and covering it with the clear rubber. Once the rubber cures, you can cut the rubber into two or mores pieces to release the pattern.
If you insist on using "old fashioned" ways of making molds, it can be very difficult and time consuming. If you make plaster molds of rigid objects, for instance, you may need to make the mold in many different pieces so that you can get the plaster off the model. The Castcraft Guides show how to use and where to get the modern materials, as well as how to use the older materials.
Do I need a lot of equipment and a lot of space?
The materials and techniques we show how to use in the Castcraft Guides are specifically chosen because they do not require a lot of space or special equipment. Making molds and castings for personal use, such as for your hobbies, can be done on a tabletop or workbench. For most projects, the only equipment you need is disposable mixing bowls and mixing sticks. For some casting materials, such as plastic resins, you should do your mixing out-of-doors in fresh air. Plaster and concrete should also be mixed outside, because of the dust.
If you get into making larger items such as concrete molds and concrete castings, you will probably want a larger workspace such as a carport or garage.
The only significant equipment you need is a kiln if you want to do ceramics; a double boiler if you want to make candles; a simple electric melting pot if you want to cast low-melting temperature metals; and a cheap glass microwave dish if you want to work with hot melt vinyl.
What is the difference between "cement" and "concrete"?
Cement correctly refers to Portland Cement by itself - a dry powder. Concrete is something made by mixing Portland Cement with aggregates such as sand and gravel and adding water. When you buy materials, you can get sacks of Portland Cement, sand, and gravel, and mix your own concrete. Or you can buy a sack of concrete mix, which has all the dry ingredients so that you can just add water.
In everyday use, most people use "cement" and "concrete" to refer to the same thing - "cement blocks" and "concrete blocks" for instance. Castcraft offers a Cement Birdhouse Project Guide. We called it "cement" because the mix doesn't contain any sand or gravel aggregates. "Concrete" sounds like a very heavy material to most people (and it usually is).
Source(s):
http://www.castcraft.com/mcfaq.htm
