As we've moved deeper into the world of dice manufacturing one of the things we had to figure out is the different materials used to make dice and the impact that will have on the final product. At a high level dice can either be made by pouring material into a mold (by far the most common method) or by using a machine to remove material from a large block (3d printing of dice at commercial scale is not yet realistic but we live in hope). For our purposes we only focus on the poured method because machined dice are wildly labour intensive and therefor incredibly expensive. In terms of the dice molding method the two most common materials are acylic and resin. In the case of resin the resin actually undergoes a chemical reaction in the mold and cures from a liquid into a solid. In the case of acrylic or metal the material is melted and poured into the mold to cool. The first really obvious difference is price. Resin ranges from 2-4x as expensive as acrylic. Why then do so many manufactures use resin for their dice?
When you're talking about dice the basic requirements are that they have uniform density and that the shape be as close to perfect as possible. Any variation in density or shape will lead to a die that is less than random and therefore biased. Getting uniform density is actually pretty easy with modern resin or acrylic materials and all but the cheapest dice will meet this mark. In the past dice could have inclusions such as other material or air bubbles that would throw them off but that isn't really a problem now except if you are buying from the lowest end factories in China. You may be thinking 'but what about the glitter or colors?' and you are correct, everything you add to a die will alter the density and unbalance it to some degree but for the purposes of a gaming die this really isn't a significant issue. The one exception to this is layered dice where the layers are made from different materials rather then one material dyed different colors. Obviously different layers will result in terrible dice and should be avoided but no major manufacture makes this error anymore although there were some examples in the 1990's.
The next issue is shape and this is where the material can matter a lot. Even if we start with a perfect dice mold when the material inside cures or cools it might change shape somewhat if the process didn't happen uniformly. This can result in misshapen dice and is a much more common problem with acrylic dice then resin but either material can be molded in an accurate shape by an experienced manufacturer. The next step in the manufacturing process involves cutting of the excess material and polishing the surface of the die. Again this step can result in slight changes in shape which will impact the die's randomness. These problems tend to appear more in Acrylic dice rather then Resin but again most manufactures using modern methods are able to work around these problems and make perfectly fine dice from acrylic. So why are we spending more money on resin dice?
The issue really is aesthetics. When manufacturing any sort of transparent dice (a design we like) resin simply holds a shine better and will look far better longer term. It should be noted for opaque dice this advantage disappears and there is no reason not to use acrylic in those cases in our opinion. This fact is something you should keep in mind with any dice kickstarter if they are making transparent dice from acrylic they are sacrificing aesthetics for cost which probably isn't what you want.
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