BASICS OF RESIN CASTING

Resin casting is an exciting and fun craft that allows you to embed or encase almost any object in crystal-clear plastic. The basic materials needed to get started in resin crafting are easy to find and relatively inexpensive.

Color dyes and pigments are optional and can be used to create a variety of special effects and backgrounds. Resin crafting supplies are available at hobby, craft and plastics supply stores.

Understanding the basics of how casting resin can be changed from a liquid to a solid will enable you to successfully create a wide variety of both practical and fanciful projects that will last indefinitely!

CASTING RESIN

A polyester resin noted for its clarity and ability to be cast in mass. In its liquid form, casting resin has a consistency of corn syrup and a slight color ranging from straw to light aqua. During the hardening process the slight color bleaches out and the resin becomes crystal clear. The styrene odor of casting resin is less objectionable if you have good ventilation when pouring. Once cured, your cast pieces will have little if any odor. Casting resin should be stored at room temperature (720 F.), out of direct sunlight, and out of reach of children. If stored properly, shelf life is approximately nine to twelve months.

CATALYST

Added to liquid casting resin, catalyst (hardener) produces a chemical reaction which generates heat, causing the resin to harden. The amount of heat generated depends upon four factors:

• Amount of catalyst used
• Thickness of the casting
• Air temperature and temperature of casting resin
• Amount of color pigment or dye (if used)

Increasing any of these factors alone or in combination changes the rate of curing or hardening. For example ...

Increasing the amount of catalyst causes the resin to cure more quickly. Over-catalyzing, however, can cause excessive heat, fractures in the cast piece, fading of embedments, or distortion of the mold. Under-catalyzing may produce a cast piece with a sticky or tacky surface.

• A thick casting cures more quickly than a thin casting.
• The higher the room temperature, the faster a casting will cure.
• Adding too much color will slow down or inhibit the cure.

During the curing process, the catalyzed resin goes through a series of stages from a liquid to a ‘soft gel’ in about 15 to 20 minutes, a ‘firm gel’ in 20 - 30 minutes and finally to a ‘click-hard’ (cured) stage in 1 to 24 hours. The length of this cycle will vary greatly depending on the four factors mentioned previously.

The period of time between the addition of the catalyst and the gel stage is called the ‘working time’ or ‘pot life’ of the resin. Generally this is about 15 to 20 minutes. Do not catalyze more resin than you can pour during the ‘working time’ since catalyzed resin cannot be poured once it has gelled. Do not pour catalyzed resin back into your casting resin can. Catalyst should be stored at room temperature, out of sunlight and out of reach of children. Shelf-life is indefinite as long as stored properly.

EMBEDMENTS

Here are some suggested objects that can be suspended or encased in casting resin: Crushed glass · Coins · Fabric* ·Flowers - dried or pressed · Glass jewels or marbles ·Glitter · Insects or biological specimens · Jewelry findings · Leaves - dried or pressed · Mechanical parts, nuts bolts etc. · Metal-coins or engraved plates · Paper* ·Photographs* · Rocks, pebbles, gravel · Seeds, peas, beans, pasta, spices · Sequins · Shells · Smaller resin castings · Stamps, paper money · Wood*

*Seal objects that have a tendency to ‘wet out’ or darken when a liquid is poured over them. Ultra-Seal™ vinyl resin glue/sealer or 4 parts white glue to 1 part water works well. Brushed on coats of glue or sealer should be allowed to dry completely before embedding the coated object in casting resin.

Any embedment must be dry, wax-free and grease-free for the resin to adhere well. Embedding plastic pieces requires experimentation as the heat generated during casting may cause some plastics to distort. For example... acrylic, polyethylene and polypropylene plastic pieces seem to be more heat resistant than those made of vinyl or styrene based plastic..

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