What is Casting Resin?

Mary McMahon
Mary McMahon

Casting resin is a resinous material used in casting. Synthetic resins are often used to make casting resin, although it is also possible to use natural resins. A wide variety of industries use resin in casting, and it is also popular with some hobbyists and craftspeople. For example, resin can be used to create casts for a model railroad, or to create thematic elements used in jewelery making. Suppliers of casting resin include companies which sell wholesale resins to manufacturers, along with craft stores and craft catalogs which sell through mail order.

Synthetic resins require a catalyst before they will harden properly to form a viable adhesive.
Synthetic resins require a catalyst before they will harden properly to form a viable adhesive.

Resin is a highly viscous fluid which hardens as it cures. In the case of synthetic resins, a catalyst needs to be mixed with the resin so that it will harden properly. Natural resins can be processed in a variety of ways to achieve the desired hardness, and these techniques can include the use of a catalyst. Resins used for casting are often clear, although they can be blended with pigments and dyes to create colored finished products.

To use casting resin, the resin is poured into a mold and allowed to harden before the mold is removed. Rubber and silicone molds are popular because they are easy to use and no mold release needs to be applied before casting. Plaster and other materials can also be used for mold making, and a number of different styles of molds are available.

Many people who work with casting resin make their own molds. Molds can be used to create standardized parts or pieces, ranging from resin beads for necklaces to resin inserts for machinery. After unmolding, a resin object can also be used in turn to create additional molds, as it will be hard and it will retain all of the details of the original mold, as long as the mold was made correctly.

Bubbling, in which small pockets of air are trapped, is probably the most common problem encountered with casting resin. Casting resin also eventually expires, and using old resin may cause problems with casting or setting. For this reason, people usually purchase resin in small batches to meet the needs of a particular project or to accommodate needs within the near future, to avoid having to discard old resin. Resins and catalysts are usually sold separately, and the blending process to add the catalyst can be used as an opportunity to add inclusions ranging from dyes to sparkles.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


i have lots of hardened resin but can;t dispose it. Local authority here said it can only be incinerated and unfortunately there is no incinerating facility here. Can someone help with ideas on what to do with this? I appreciate it. --Eric.


I have a table top, wood bottom, brass ring enclosure, petrified wood placed on the wood bottom then resin was poured in to enclose the petrified wood and hardened.

I want to dissolve the resin to remove the petrified wood with the wood pieces intact. Any ideas?

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