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Photopolymer Plates and Magnesium Dies If you would like to make a mold with computer graphics or logos, you should consider using printing plates made from photopolymer (also referred to as flexographic printing plates) or hot stamping dies. Hot stamping dies are made from a process called photoengraving, and can be made of magnesium, copper, brass, steel, and silicone. Printing plates and hot stamping dies are typically used in printmaking, embossing, imprinting, rubber stamping, hot stamping, and foil stamping industries. Both produce a die that has the desired computer graphics or logo either raised or recessed on it. Once the plate or die is made, it is mounted on a base, and then a mold can be made. Printing plates and hot stamping dies are made using a photochemical process that produces a plate or die with the graphics being shown in relief. The photopolymer or magnesium is designed to harden or cure when exposed to UV light. Usually, a stencil or transparency is created in which the desired image is clear and all other areas are black. Any area that is clear will be exposed to the light and will harden. Any area that is black will not be exposed to light and will not harden. This is very important to understand. Your computer graphics have to be perfect or else your plate or die will not come out right. It is best to use vector based line art. See Drawing the Design for an explanation. After the printing plate or hot stamping die has been exposed to the UV light, it is washed using either water or special etching chemicals. This will remove all the areas that were not exposed to the UV light. The computer graphic or logo will be raised on the plate or die. The height that it will be raised, or the "relief" as it is called, depends on the type of plate or die used. There are many different manufacturers of printing plates and many photoengravers who process hot stamp dies. Each has its own product lines, but the plates and dies are usually made in industry standard sizes. Once the printing plate or hot stamping die is made, it is mounted on to whatever shape or object you would like the chocolate or candy to be. Then you can use any of the moldmaking methods, such as vacuum forming or silicone rubber mold making. If you will be using printing plates or hot stamping dies to make your custom chocolate or candy molds, you must choose the product according to the mold making method you will be using. For example, if you intend to make a vacuum formed plastic mold, you must choose a product which can withstand heat. Or, if you are making a silicone rubber mold, you need a product that can hold up in liquid for a long period of time. We will discuss this in more depth in future tutuorials. You can process your own printing plates, but if you want hot stamping dies, you will have to have them made by a photoengraving company, or photoengraver. Of the two, printing plates are much less expensive and can be done in your own home with some practice. Hot stamping dies cost a bit more, but are much better to use, especially when making vacuum formed molds. |
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